Here's a video from Arctic Fire 2012 in which I demonstrate the art of niello.

This is a short, 7 minute version, but you can see the full hour length version Here.







And my undergraduate thesis at Maine College of Art:



-An Exploration in Niello-


Cup for the Moon. Silver, niello, garnet. J.Loose, 1993.





An Exploration in Niello



Submitted as partial fulfillment toward the degree of Bachelor of Fine Arts at the Portland School of Art

April 28, 1993

J. Arthur Loose

Tim McCreight, Department Head

Alan Perry, Instructor

Introduction

What is Niello?

Niello is most commonly an alloy of silver, copper and lead which is '...converted with the addition of sulphur into a mixture of sulphides.' (Fike, p.1) As the formula for niello requires an alloy fused with sulphur, it is referred to as a metallic sulphide compound. (Untract, p.382) Niello is called a fusion inlaid alloy, which means that is is flooded over an uneven surface with a higher melting point. The excess niello is then lowered to the level of relief and thus exposed in contrast with the base metal. Niello is a '...dark grey black tone with a faintly perceptible shift to a blue cast.' (p.1) The depth of the color depends upon the depth of the niello itself as well as the exact composition. Niello is traditionally applied to gold and silver and the contrast created by this dark material is striking and beautiful. The patterns '...created by the niello inlay and the bright color of the parent metal [offer] endless possibilities of pleasing contrast.' (Untract, p.382) Nearly every culture to have developed basic metallurgical skill has been found to employ niello. Niello dates back as far as '...3000 years ago in Dynastic Egypt, [where] methods were developed for inlaying this easily fusible sulphurized alloy...' (ib.) Among others, the '...Persians, Migration Period peoples, Greeks, Romans, Celts, Anglo-Saxons, Germanic tribes and Byzantines,' (ib.) used niello extensively. During the Renaissance, especially in Italy, artists such as Benvenuto Cellini '...brought the process to a peak of perfection.' (ib.) The fact that '...almost all European languages use the Italian term niello, from the Latin nigellus,' (ib.) serves to remind us of their excellence in the medium. Phillip Fike, an American metalsmith well versed in the art of niello, has suggested that even the great tradition of the Printmaker derives from that of the Niellist. Fike states that,

From the 15th century onward Niello has a connection, if not one
of primal importance, to the invention of Chalcography. It remains
unproven, but the evidence awaits further research. A survey of
printmaking in 15th and 16th century Italy will assert deeper speculation.
The individuals associated with [printmaking's] use, especially in the
Florentine environment, are called 'Niellists,' and their engravings, and
printed impressions lifted from them, are called 'Nielli.' (Fike, p.1)

Although niello is generally applied to silver and gold, it will also fuse to metals '...whose melting point is considerably higher than that of the niello alloy, such as copper, brass, bronze, nickel alloys, or steel...' (Untract, p. 383) Niello was often used on armor and weapons from at least the ninth century up until the 18th century. I think that perhaps there could even be a connection in the engraving traditionally associated with contemporary firearms, which would be well suited to niello application. In modern times, niello production still occurs in a few centers such as Bangkok, Thailand, where it is '...flawlessly executed,' (ib.) Southern Morocco and Russia. Russia, in particular has a long tradition of niello use. Theophilus in his treatise, On Divers Arts, states that '...if you study [this book] diligently, you will find here whatever kinds of the different pigments Byzantium possesses and their mixtures; whatever Russia has learned in the working of enamels and the variegation of niello...' (Theophilus, p.13) Even today this tradition lives on in the Vologda Region, '...where a contemporary factory called Northern Niello continues the production of niello ornamented jewelry...' (Untract, p.382) In the Western world, niello is employed almost entirely within the 'studio art,' context...metalsmiths such as Phillip Fike who both create the material and use it. I know of only two commercial sources for niello, one in Germany (Karl Fischer of Pforzheim, W. Germany) and a California-based company whose flier I have from 10 or 15 years ago. The commercial production centers who do not sell niello refuse to disclose their secrets and I believe this is the proper course. Companies who market raw niello seek to undermine the true nature of niello. As Phillip Fike says, '...The artist, artisan or craftsman, i.e. a niellist, in control of the materials and techniques associated with niellowork, I believe, will begin to agree that this art was born deep in Alchemy...' (Fike, p.1) I stand firm by this belief, understanding that Alchemy is an endeavor of the spirit, and thus niello as well.

Oh, thou discreetest of readers, marvel not that I have given
so much time in writing about all this, but know that I have not
even said half of what is needed in this same art, the which in
truth would engage a man's whole energies,
and make him practise no other art at all.


-Benvenuto Cellini on the Art of Niello, from The Treatises on Goldsmithing and Sculpture.



All of the original trials resulted in pieces that looked much like this one;
without the bracteate-like attachment. They are periodically referenced in the
descriptions. Some of them are still in the original thesis at MeCA. I will
attempt to photograph what is left of them the next time I visit...




Recipes with Specific Procedures

Cellini, Heinrich, Fike, Theophilus

Cellini:

1 part Silver,2 parts Copper,3 parts Lead, Sulphur in excess

The Making

The Treatises of Benvenuto Cellini on Goldsmithing and Sculpture, published first in 1568, just three years before Celliniπs death, offer a first-hand account of the Rennaisance art of Niello. Cellini devotes his first chapter to this art which '...in [his] youth from [his] 15th to [his] 18th year [he] wrought a good deal at...always from [his] own designs, and was much praised for [his] work.' (p.9) Celliniπs recipe calls for '...an ounce of the finest silver, two ounces of copper well purified, and three ounces of lead as pure as you can possibly get it.' (p.7) Cellini then melts the silver & the copper in '...a crucible in a goldsmithπs blast-furnace...' (ib.) When the two are fully melted the lead is added and he advises that charcoal be used to remove the scum which '...the lead, according to its wont, will make.' (ib.) Cellini then fills '...a little earthenware flask about as big as your fist,' and a neck not '...wider than might hold one of your fingers,' (ib.) with sulphur, finely ground. Into this flask Cellini pours the molten metal, '...while quite fluid and hot.' (ib.) Cellini agitates the flask, stopped up with clay, until it is cold. The flask is then broken and the '...little grains,' (ib.) removed. This process is repeated twice (with the addition of a 'grain,' (ib.) of borax at the melting stage.)

I began by finding a potter who could create Celliniπs 'little earthenware flasks,' and here I must give credit to Kate Prideau. As Cellini describes them, they were '...about as big as [her] fist with necks not ...wider than might hold one of [her] fingers.' (ib.) These flasks I had made worked quite well. I melted the silver and copper in the crucible with the oxy-propane torch, contrary to Celliniπs 'goldsmithπs blast-furnace' though I feel that is likely of little consequence. To this molten metal I added the lead which owing to its volume almost didnπt melt. When molten I removed the ≥little scum,≤ and poured into the flask which soon began emitting a sulphur plume. I stopped up the flask with 'a little clay,' and began to 'agitate' it, holding it in an insulated glove. Take heed! Cellini has forgotten to enlighten the foolish who make sulphur-niello bombs by creating pressure chambers full of the burning stuff. I will spare you this excitement and tell you not to stop it up too tightly. Upon breaking the flask I found a little niello meteorite all black and crusty. The sulphur had not entirely burned off so I allowed for this before adding the re-molten mixture to the second flask full of sulphur. The first flask had also a crust formed around the inside, where the sulphur and traces of niello had attached themselves most fervently. I had to break the flask nearly to powder in order to reclaim the niello granules. In the process I inadvertently incorporated some of the ceramic into the remelted niello. ( In an attempt to avoid this situation I first tried to flux the inside of a flask with borax, but the heat required to melt the borax cracked the flask. Perhaps pouring the borax in the flask while it is still in the kiln would work.) At any rate I shook the second flask until it sounded like there was solidified niello inside and then I poured out the liquid sulphur before it solidified. This allieviated the crusty-niello problem, which occured as a result of letting it all cool together for too long. I broke the second flask and repeated all of this again until I discovered another oversight. The nugget of niello created by this process still had sulphur all over it. This makes it impractical to use straight from the flask. I remelted a fourth time (and inadvertently spilled about half the niello,) and waited for the sulphur to burn off...it seemed infused into the niello so that if I stirred it flames erupted out once again, and this continued for quite some time. Eventually I poured it out into the angle-iron while a minute purple flame traced its path. The result was one of the best looking rods to date...extremely shiny, deep black and crisp when broken.

In order to compare methods and formulas I then made a batch of Celliniπs niello according to Fike, with the exception that I poured it on a steel plate as von Nuemannπs book suggests. The niello formed a hard, black cookie that had shapes on the top suggestive of underlying bubbles. Cutting through the diameter of one of these structures revealed that it was merely niello which had, for some reason, formed these raised areas. Upon breaking, the cookie showed an even, crystalline-like fracture...shiny mica-like formations.

The Application

(Using the niello made according to Cellini)

I took a piece of the niello and ground it finely upon a steel plate with a hammer, using a slow, crushing motion rather than striking. Cellini suggests pliers but I found it difficult to contain the flying pieces. Careful to grind it to '...grains & not to a powder,' (p.8) I then washed the niello according to Cellini & placed it upon the silver sample to the '...thickness of the back of a table-knife.' (ib.) I powdered over it '...a little ground borax,≤ but ≥...not too much.' (ib.) Rather than the heat of the forge, I used an acetylene torch and heated from beneath while holding the piece in my tweezer-like tongs. Soon the niello flowed quite evenly and upon removal of the excess stuff I found a relatively good sample with only minor pitting...perhaps due to holes already existant in the sample.

(Using the niello made according to Fike)

I took a small section of the rod and crushed it to grains on an anvil, using a hammer and a slow, grinding motion. I took the grains, washed them in water and placed them on the sample to the depth '...of the back of a table knife.' (p.8) I sprinkled a bit of borax on it and heated it from below with an acetylene torch. The flux bubbled, glazed and then the niello melted; forming a pool of liquid black stuff. The sample when cleaned was dark and clear. There are some small bubbles visible in the niello, but perhaps if I had burnished it as Cellini calls for I would have '...stopped [them] up.' (p.9)

The Assessment

Celliniπs method of making seems to me a little excessive for todayπs metalsmith. The ≥flask≤ system is wasteful and a bit more dangerous than other methods. The final product is not any better than by other methods; in fact, it is more likely to have foreign matter in the form of ceramic particles. The sample does not display any qualities over the second that leads me to believe Celliniπs method works better than any other. The second result, (made like Fike) was a good niello flow with only some minor pitting. The details of the stamping are slightly unclear, but I canπt find just one conclusive reason. Perhaps the stamping itself is to blame or perhaps, as the slight pitting might suggest, the niello with its high lead content ate through the finer details. In contrast to his method of making, Celliniπs method of applying works quite well for the modern metalsmith. Replacing the forge with a torch poses only one question...would the charcoal-fed forge create an advantageous reducing atmosphere? Whether the answer be yes or no, I think it is probably incidental to Celliniπs thinking...more likely it was simply the best available heat source in his day.



Fike:

6 parts Silver,2 parts Copper,2 parts Lead, Sulphur in excess

The Making

Phillip Fike, as a modern niellist, describes the making of niello in a much more relevant manner than most sources. Fike recommends using an ordinary Burno crucible into which copper and subsequently silver are melted with an oxy-acetylene torch. When the two metals are fully blended, Fike adds the lead and swirls the crucible to mix the '...alloying mass gently.' (p.5) At this point Fike suggests that the proper swirling motion requires an accompanying sway of the backside. Once the alloy has been properly swirled, Fike introduces a '...heaping tablespoon of sulphur onto the alloy,' (ib.) This should be done '...without hesitation or timidity, as the sulphur is immediately afire, and so may be the spoon, which you might return to the bottle, possibly afire without knowing it...' (ib.) Fike then uses an iron stirring rod to '...'muddle' everything that is melting and burning,' (p.6) After burning off all of the sulphur '...the niello will be at about 1200∞ F a medium red color if you can read it.' (ib.) The alloy is now rotated as before in order that '...it [washes] over itself in a circular flow. A cinder of residue will form as the mixture cools.' (ib.) Fike maintains that this cinder is a '...critical point,' (ib.) as it '...might in fact have a cleansing effect on the balance of the melt.' (p.5,) When this cinder has formed from about 1/3 of the original mixture, the niello is poured in the angle iron (coated with carbon.)

The Application

Fike first states that the metal to receive the niello be carefully cleaned by abrasive scrubbing, pickling & degreasing, sandblasting or electro-cleaning. The work is fluxed with white pasting flux diluted 25%; Batterns flux (full strength) or as I recall from a workshop I attended, a 50/50 mix of handy flux & Prip's. If using the rod straight from the pour, the work is '...lightly fluxed,' (p.7) using one of the aforementioned mixtures. When the flux is '...fully active and glazing the surfaces,' (ib.) the rod is put to the hot metal. If using a powdered niello, it is '...mixed with the flux, and then fired such as with enamel in a kiln...' (ib.) According to Fike, '...niello is a quick moving liquid at 1000 degrees. It becomes firm [at] about 875∞' (ib.)

The Assessment

I followed Fikeπs directions quite closely as they are written for the modern metalsmith. This is, in fact, the method with which I am most familiar and the only method I have actually been shown . I ran into no problems save the exact timing of the pour...but I have become better at this. My first batch was repoured once, and the second pour of the first batch came out with a very clean, shiny surface and broke clean and crisp, with uniform black ends. Upon application in the rod form, the niello flowed quickly and smoothly. The cleaned sample shows sharp edges and no pitting, although there are some minor holes that could probably be filled. On the whole I find Fikeπs methods refined, they seem to work well and Fike himself maintains that '...research of other published formulae with proportions vastly uneven for every ingredient, turned [his] attention to methods as the main key to manufacturing a fine niello.' (p.6)



Heinrich:

1 part Silver,2 parts Copper,3 parts Lead,6 parts Sulphur

The Making

Mr. Leonard Heinrich has the job of my envy: Armorer for the Metropolitan Museum of Art. He has apparently repaired many objects with these methods of making & applying niello. The silver, copper & lead are melted and stirred as in Fike. This mixture is poured into another crucible which contains the sulphur. Some recipes call for the sulphur to be molten before the alloy is introduced. I chose to simply drop it in the powder & observe the results. The sulphur immediately became aflame with the heat of the metal and soon the crucible was filled with a black tar-like substance. Heinrich now says to cover the crucible and allow it to cool. When I came back to the mixture, the molten sulphur was hardened in the bottom of the crucible. After much head-scratching I decided to reheat the sulphur to a liquid state and search for the niello with tweezers. I soon discovered a black nugget which I melted down as called for in the recipe. Heinrich pours his niello through a sifting screen and into a bowl of water and I followed his example...Take heed!!! The niello makes a frightful noise upon cooling. After washing the mixture by running cold water over the bowl I set it out to dry in the sun. This method of pouring into water creates niello particles as fine as powder and as large as pellets. I ground up an even cross-section of this material on a steel slab (Heinrich calls for an agate mortar and pestle).

The Application

Heinrich, like Fike, wets his work with handy flux the consistency of milk. However, here Heinrich departs and makes a paste out of the niello and a saturated ammonium-chloride solution which he applies as an enamel. I continued to follow Heinrichπs directions and heated the sample from below on a steel plate. The venting hood pulled the plume of grey smoke which subsequently flew from the sample as a result of the ammonium-chloride solution. The niello eventually melted and flowed evenly; however, when the sample cooled it had an uneven surface with a grey crust in places.

The Assessment

The first thing I noticed as I scraped off the niello was that it was much harder than other nielloes. A triangluar scraper barely cut into the stuff and when it did it bit too deeply; chiseling rather than scraping. I sanded the sample down with a 180 grit and even then it took some time. As I moved down the layers I began to notice many small bubbles. These stopped just short of the surface for the most part but there are a few pits and holes visible in the final product. Some of the areas show larger outlines than the stamp made; I thought that perhaps I simply wasnπt down to the level of the relief but then as I sanded further other areas began to disappear. This and the area on the back of the sample (behind the first 'I') lead me to believe that the lead had began to eat the silver. The greyish cast still visible in the recesses of the sample and prominent on the unfinished surface of the melt are further indicators of this hungry lead. (Persian #1 & Thai for example.) As I heated the plate from beneath I watched closely for the signs of melting...but before the niello actually melted it turned a dry grey. I think the ammonium-chloride had something to do with it as the niello turned grey precisely after the smoke from the ammonium-chloride ceased. It was also the same color as the smoke itself...an intuitive judgment on my part. Perhaps the plate used to heat the sample on was too thick (1/8 inch)...I think possibly that the sample may have heated too slowly...would a thinner plate heat quicker and thus better? The fault most likely rests with the method itself or my personal experience with the method rather than the formula. As the Armorer for the Metropolitan, perhaps Heinrich is used to working on larger pieces with steel and silver damascening all creating a different set of circumstances and factors.



Theophilus:

4 parts Silver,2 parts Copper,1 part Lead, Sulphur in excess

The Making

Theophilus gives a very good account of the Dark Ages method of making and applying niello. Theophilus divides the metal, placing the copper and the silver together in a casting crucible. He then states, 'Take yellow sulphur and crush it small; put the lead and some of the sulphur into another casting crucible.' (p.104) The silver & copper are melted, mixed and the crucible containing the lead and a portion of sulphur is added. This is '...mixed again vigorously with a piece of charcoal,' and poured '...into the other casting crucible over the sulphur,' which has been '...put therein.' (ib.) This crucible is then '...put into the fire until [its contents] melt.' (ib.) It is stirred once again and poured into an iron ingot mold. Before it hardens it is hammered, heated slightly and hammered again, '...For the nature of niello is such that, if it is hammered when cold, it immediately breaks up and flies into pieces; on the other hand it should not be heated so much as to become red because it immediately melts and runs into the ashes.' (ib.) When the niello is thin, it is placed in a deep pot of water and crushed with a pestle until it is extremely fine. It is then placed in a goose-quill which is stopped up. Fike has suggested that the goose-quills serve as airtight containers for the powder, which is more liable to break down in the presence of oxygen.

I followed these directions as closely as possible, given the thousand years or so between author and artist. I melted the silver & copper, stirred with charcoal and added the lead/sulphur mixture. This I then poured over the other crucible with the sulphur in it. I heated this crucible from the bottom and sides first, mimicking the effect of a forge fire to the best of my ability. The sulphur soon melted and I played my oxy-propane torch over the niello itself and waited until the sulphur had burned off entirely. I poured into the angle-iron, waited for it to cool slightly, placed it with tweezers on the anvil and pounded lightly. I placed it in water and ground away...an excellent solution to the problem of ≥springing niello aside.≤ I set it in the sun to dry.

The Application

Theophilus takes '...some of the resin called borax,' (p.105) and grinds '...a small piece of it with water in the same pot, [not the pot of water the niello was ground in] so that the water is rendered just turbid from it.' (ib.) The place you want to cover with niello is wet with this water and the quill is tapped to drop powder over the area until '...you have covered it all.' (ib.) Theophilus then places the object to be nielloed in a heap of '...well burning coals,' taking care that '...no coal is placed over the niello or can fall on it.' (ib.) Theophilus goes on to state that '...If [the niello] does not become full everywhere at the first heating, wet it again and put niello on as before, and take good care that more is not needed.' (ib.)

I also followed Theophilusπ directions for application rather closely. Modern borax already comes with water in a hydrous form. Therefore, to simply apply this powder has a similar effect to mixing the prepared solution. I did not use goose-quills but presumed that a ziplock baggie may perform the twentieth century funtion. Niether did I use coals, and this may prove to have something to do with my results; coals have a reducing effect and several niellists suggest that a reducing atmosphere is benificial to a good niello flow; mine has silver in it as well as pitting.

The Assessment

Theophilusπ method seems adequate for his day. The word 'torch' may be substituted for 'forge,' and the text reads contemporary up until the goose-quills. I think perhaps the sulphur that is added along with the lead during the first melt is extraneous, but I donπt think it would cause any harm either. The method of grinding underwater neatly solves a messy problem and Theophilus has acknowledged the deterioration of niello in the presence of oxygen; something others have not. Applying the niello in powder form with borax seems to work well enough, unless perhaps it is a contributing factor to the recrystallization that occured in my sample. Borax melts a bit higher than other fluxes and may thus have caused me to overheat the sample. Theophilusπ warning about re-heating niello is also sound advice, as some of my earliest attempts to repair niello have shown.

On the whole I think that this niello formula should work as well as any other. Theophilusπ methods could only be improved slightly with todayπs technologies. Theophilus probably knows his niello and I think that the recrystallization is likely the result of the borax flux...another paper might tell us whether or not there were other fluxes available for Theophilus to have used instead. It might also tell us whether the borax of Theophilus is the borax of today or even if a translatorπs error is at hand.



Recipes without Specific Procedures

Augsberg #1 Bolas #1 Karmasch Modern French Persian #1 & #2 Pewter Experiment Pliny Rucklin #1 & #2 Russian Spon Thai Wilson

Augsberg #1:

1 part Silver,1 part Copper,2 parts Lead,Sulphur in excess (1/2 cup)

The Making

I first made Augsberg #1 in the manner of Fike, pouring the melt into an angle iron at about a 20∞ incline. The first cast had a silver line running down the underside. This is indicative of a bad pour wherein the silver has recrystallized as the result of it taking place at too high a temperature. (Fike) It also had an iridescent surface toward the end of the pour and a collapsed length of about six or seven inches at the front. I broke up the niello which was slightly malleable and made a distinctly crunchy noise. The broken ends appeared solid silver, solid grey and mixed. (These all indicate an uneven pour.) After remelting and adding sulphur once again (Fike) I poured into the same iron with what appeared to be a better result. The niello had an even, dark tone and the ends seemed relatively even when broken. The surface was a dull matte; according to Fike it should ideally exhibit a clear, shiny surface.

The Application

Upon application Augsberg #1 flowed easily across the surface of the silver sample. Again I applied the ≥Splendid Rod≤ in the manner of Fike, using an acetylene torch with a reducing flame and a flux of 50/50 Prip's & handy. The flame was played primarily underneath the sample with a steel screen supporting. Upon removal, the sample revealed both small areas of pitting and small areas unfilled. These were slight enough that I believe they were the fault of the application process and not the niello itself. I then attempted to apply Augsberg #1 to a cylindrical bead about one-half inch thick by about an inch in diameter. The bead had an overlay design, using the niello as a negative element. To apply the niello I set a hand drill in a bench vise and had an assistant turn it at a slow rate. A small rod of tapered steel affixed the bead to the rotating drill. Again I used the 50/50 mix suggested by Fike and the acetylene torch. Once I had sufficiently covered the bead (to all appearances) I began filing down the surface of the niello only to uncover small unfilled areas. My best guess is that these are the result of both an uneven application and the sheer depth of the area filled (about 1/8≤.) Several times did I attempt to fill these small spaces only to discover that I had recrystallized small areas of silver in the niello.

The Assessment

I suspect that most of the problems encountered with regard to Augsberg #1 are the result of my own inexperience with the material. In the course of this study I have become more sensitive to the point at which molten niello should be poured. I suspect that even the second pour was made a bit too soon, while the metal was too hot. Pouring too hot seems to result in the aforementioned silver vein running through the length of a rod-like casting. It also results in the collapsed section of the rod where, like a lava tunnel, the outer skin of the pour cools and hardens before the inside, which continues to run down the length of the angle iron. Both of these sections are bad niello, for they contain differing amounts of the components of the alloy. As far as the application process goes, I also believe that my methods are more at fault than any quality intrinsic to the composition of this particular formula. Re-heating niello is ill-advised by almost any source and Fike specifically cites this as a probable cause of silver recrystallization.



Bolas #1:

2 parts Silver,4 parts Copper,1 part Lead, Sulphur in excess

The Making

Bolas #1 is an alloy low in lead and high in copper. I melted the copper first because of its sheer volume, added the silver, a pinch of borax and swirled the alloy. To this I added the lead which disappeared in an instant. I muddled in several heaping tablespoons of sulphur with a steel rod and burned it off completely. I swirled the mixture as it cooled to form the cinder and poured into the angle-iron. The pour contained roughly half of the original alloy as the rest lay hardened in the crucible. The mixture had solidified quicker than most, perhaps because of the high copper content. I melted the remaining cinder, swirled again and poured as before. I now had two rods, one from the original melt, one from the cinder, and the remaining bit of drudge from the cinder of both pours. Both pours were uncharacteristically red as they cooled in the angle-iron...again I suspect because of the high copper content relative to the content of lead. The redness was concentrated near the front which suggested an uneven pour...upon breaking both rods had silver veins. I remelted both together in an attempt to re-fuse the elements and get a good pour. I re-sulphinated the alloy (Fike) and poured it off again with results very much similar to the previous pours.

The Application

I took what appeared to be a good section of the rod, an area from about the middle, just after the area which glowed red for longer than the rest. This area of excess heat lay toward the front of the pour in a globular shape thicker than the remainder. I fluxed the sample with a dilute mixture of handy flux and heated from below with an acetylene flame over a steel screen. The sample achieved a high temperature and still the niello would not melt so I heated the niello itself. I was able to drop melted sections of the niello onto the heated sample but it would not flow. The result is a globular mass atop the silver sample. The niello as it exists would be completely incapable of fusing any area of intricate design.

The Assessment

It seems that the high content of copper relative to the lead created a niello reluctant to melt and flow. The redness observed during every pour would indicate this reluctance to flowing...most nielloes exhibiting a red glow are still fluid. The alloyπs inhibited flow also determined the poor result of the sample...a small spot on the back suggests some silver dissolving into the lead. I think that perhaps this high copper to lead ratio makes for a niello whose properties might work better on a material with a higher melting point...perhaps even steel. In general it seems fair to say that Bolas #1 is a niello ill-suited for either Fikeπs method of pouring into an angle-iron as the direction of the flow makes it easier for the alloy to separate into heavier elements. It also seems fair to suggest that the alloy might be better used on other materials although the qualities of the niello might alter when made differently.



Karmasch

15 parts Silver,90 parts Copper,150 parts Lead,750 parts Sulphur

The Making

Karmasch, an 18th century Russian niellist, recorded this mixture and it has come to my attention through Robert von Nuemannπs book. I melted the silver and the copper in a crucible, swirled it, added the lead and stirred. In response to Heinrichπs recipe where I poured the niello into powdered sulphur I melted the sulphur prior to introducing the alloy just for comparison. This is the method described in von Nuemannπs book. The niello disappeared into the black, flaming puddle. I added sulphur and allowed the stuff to cool. At this point the method described becomes vague. Do I remove the niello from the mixture (to be remelted according to von Nuemann,) or do I burn the sulphur off entirely? For the sake of comparison I burned off the remainder of the sulphur, which took a while but produced a perfectly acceptable result...I poured the niello into the angle iron & it came out with all the signs of a good pour...deep, rich, blue-black, a shiny surface all around and exhibiting no evidence of silver recrystallization.

The Application

I applied Karmasch to the sample in the rod form using a thin mixture of handy flux. The niello flowed smoothly and flooded the surface of the silver. The only problem I encountered during the application process was the flux which bubbled up and had to be removed with a solder pick. I removed the niello with a triangular scraper and sanded down with a 220 grit sandpaper. There were only a few depressions in the niello that showed as pits...a reflooding would probably eliminate them. I burnished the sample in an attemt to see if that would work to smooth them down. Burnishing gave the sample a shiny surface which makes the niello difficult to see in certain light. This effect is not necessarily undesireable although it also has the effect of blurring the lines of the niello.

The Assessment

I found Karmasch to be an excellent formula although I am uncertain whether or not the formula itself deserves the honors. Perhaps the method of pouring the alloy into molten sulphur is a more effective method or perhaps Iπm merely becoming more profficient. My general experience is contradicted by the success of this niello; most formulae high in lead have been the source of much frustration.



Modern French:

30 parts Silver,72 parts Copper,50 parts Lead,384 parts Sulphur,36 parts Borax

The Making

I made Modern French in the method of Fike, melting the silver & copper together in a crucible with the oxy-propane torch. I then mistakenly ommited the lead and proceded to the next step. I added the borax & sulphur already mixed together to watch what would happen. The mixture flamed as usual and eventually the sulphur burned off...nothing out of the ordinary until I poured the alloy onto the steel plate where it cooled with a red glow in a thick flow. I then discovered the lead I had forgotten sitting atop the venting hood. I remelted the alloy and added the lead. I poured the niello onto the steel plate where it cooled with a small red glowing spot off to one side. I then attempted to hammer the cookie as it '...hardens and embrittles the alloy which makes it easier to break up.' (Untract. p. 385) Upon breaking the newfound cookie I discovered a small silver bead with a crystalline surface that the niello itself did not adhere to. In order to see what, if any effect this might have upon the niello I went ahead and applied it without any portion of the silver bead.

The Application

I pasted the silver sample with handy flux diluted to about 25% and placed the granules of niello evenly across the surface. The granules were about 3 mm square and were placed about 1 mm from each other. I then coated the niello with more handy flux (diluted) and heated from below on a steel screen. The flux bubbled, the niello went grey for a few seconds and then turned completely liquid and black. It flowed evenly and true with the only obstruction being a large blob of flux. I deftly removed the offending blob with a pluck of the tweezers and let the sample cool.

The Assessment

The niello cleaned off easily and produced and even greyish tone. It is not as dark as some, but it fused and flowed just as well as any other. Some areas, particularly the lower right leg of my little 'Eiffel tower,' show excellent detail. I cannot say how much of this has been affected by either the late addition of lead or the methods of making & application. It would seem fair to say that none of these factors proved detrimental.



Persian #1:

1 part Silver,5 parts Copper,7 Lead,24.5 parts Sulphur

The Making

I made Persian #1 according to Fike, using the oxy-propane torch and the burno crucible. The silver & copper melted less easily than other formulas, perhaps because of the higher percentage of copper. The addition of the lead made a greenish light for an instant and made a silvey grey liquid with a mercuric look about it. The lead I added by the spoonful, 'muddling' it in as in Fikeπs method. This took quite some time and the sulphur seemed to form a crust that was often hard to penetrate with my iron stirring rod. While I fussed about with this sulphuric crust the alloy below it cooled off and when I finally poked through, it had solidified. This tedious process I repeated several times until all 24.5 grams of sulphur were gone. When I poured the niello it came out with a dull matted surface. Upon breaking it was obvious that I had an uneven cast: the end of the pour was a smooth, friable U-shaped rod while the front was a rough, round, pliable bit of stuff.

The Application

I chose a piece from the middle and applied it in rod form to a sample with a 50/50 mix of Prip's and handy flux. The niello turned a bright red and seemed not to want to melt, then began to eat silver. I remelted the remainder of the niello and recast it. I applied in the same manner and I got very similar results, right down to the second sample, also discussed below. I saved some of the second rod and remelted the other sections with any appearance of hope; the front of the pour after the 'U' shape started to become rounded but before it got truly rough and ugly. This remelt cast with a slightly better appearance and a slightly better result.

The Assessment

This Persian niello failed to show any redeeming qualities whatsoever. Each remelt failed to pour well and each sample failed to fuse with the possible exception of the third. The first sample began to fuse only after I took the silver to a glowing orange where it actually started curling at the edges. The second sample also failed to fuse even at an extremely high temperature...in fact, the second sample merely began eating the parent silver away. The third sample fused only at a high temperature with evidence of pitting and muddled tones. The only unusual factors I can come up with are the high percentages of copper and lead relative to most other recipes. The matter of the sulphuration may also have some unknown effect on the quality of the niello. I am more moved to blame the formula itself as I received similar results with a similar niello, namely the Thai mixture. The evidence seems to support a theory that these mixtures simply donπt work very well.



Persian #2

15.3 parts Silver,76 parts Copper,106 parts Lead,367 parts Sulphur,76 parts Ammonium-Chloride

The Making

I made the second Persian niello by melting the silver & copper together, swirling, adding the lead and stirring. I poured in the ammonium-chloride and observed as it burned off with a grey stream of smoke. When the grey plume had ceased to fly I added the sulphur which burned off with its characteristic yellow smoke and blue flame; indeed, this was the most aesthetically pleasing of all the nielloes to date. I allowed the alloy to cool, wash over itself and when I finally released it down the angle iron it flowed both longer and more liquid than usual. It cooled and soon the niello broke up into segments about 2 to 4 inches in length which began to bend upwards at the ends. The niello had a deep black surface with a distinct shine...some of the ends had drops with exceptionally shiny dark surfaces.

The Application

I applied Persian #2 in rod form with a dilute mix of handy flux. The niello flowed easily enough and I thought I had a good sample. When I scraped the surface I soon observed that some of the larger areas were depressed. I reapplied niello to these areas and allowed the sample to cool. Upon final cleaning the sample showed areas of recrystallization (the lower part of the ≥R≤) and unexplained areas of unusual size (the 'E' should be much smaller). The tone of the niello is not now nearly as deep as I had thought it might be, judging by the color of the original rod.

The Assessment

Persian #2, another niello high in lead, seems somewhat problematic. I can come up with no reason for the recrystallization and the areas of unusual size. I am also positive that the first time I applied Persian #2 to the sample the unfilled areas were filled...perhaps it contracted as it cooled or the large areas may be the result of an early stage of niello eating silver. In any case I was surprised by the results of the sample when the original pour looked so good.



Pewter experiment:

2 parts Silver,2 parts Copper,6 parts Pewter, Sulphur in excess

The Making

In order to impose as many controls as possible (admittedly not enough to be properly scientific) I substituted pewter for lead and used Fikeian recipe and methods. I melted the silver & copper, added the pewter as usual and muddled the sulphur in, all the while executing the proper swirls and backside motions. At the moment of pour I watched as a silvery rod of liquid shot out of the black front of the cast. I remelted several times and always came out with the same results...the pewter was not fusing with the alloy and would remain liquid long enough to come out of the front of the pour.

The Application

Attempts to fuse the stuff proved completely useless.

The Assessment

I suspect that the pewter either has too low of a melting point or does not become a sulphite as do silver, copper and lead. I make this assumption based on the observation that the metal shooting out the front of the pour is not blackened.



Pliny

3 parts Silver,1 part Copper,2 parts Sulphur

The Making

The Pliny formula is an unusual niello as it calls for absolutely no metal to lower the melting point. Herbert Maryon, speaking of a Roman niello states that '...This niello was composed of silver sulphide only: a material which became plastic far below itπs melting point. In powdered form it may be filled into recesses in a work, and after gentle heating it may be moulded and burnished to its final level.' (p.161-162) I had many problems with this niello. The first being that the alloy was not mixing entirely. Upon casting the rod it, appeared slightly less fluid than a normal niello. Upon breaking (or sawing, as the case may be, for it is not friable at all) the 'broken' ends revealed a brassy substance which is most likely the un-sulphured alloy of the silver and copper.

The Application

I found a section of the rod with less of this un-sulphured alloy than other areas and filed it down powder. I placed this powder on the sample and fluxed it with Prip's flux. I heated it up and watched as the piece heated to dull red with no observable changes. I attempted to 'burnish' the material in with a polished steel rod with no real success. Upon cooling the sample bore a rough, dark coppery surface with obvious granules from the filing. This was much more difficult to remove than the normal nielloes; a steel scraper had little to no effect. On reaching a level surface, the sample showed the same brassy alloy fused into areas of the base metal. Some areas show a dark color infused into the metal. This dark color is not a patina; it is probably the result of particles of the ensulphured alloy that fused to the sample.

The Assessment

This formula does not seem to want to fuse into a uniform alloy. Both times I attempted to make this alloy the outer surface of the pour appeared to be a sulphite but the interior showed a pure silver/copper alloy. Both materials have a very high melting point and therefore the niello is not applied in the same flooding manner as most. There must be both a way of making the alloy and a way of applying the alloy with which I am not familiar. Upon discovery of these methods I am sure that the formula would work just fine, if not very differently from other recipes.



Rucklin #1:

3 parts Silver,5 parts Copper,7 parts Lead,6 parts Sulphur,2 parts Ammonium-Chloride,24 parts Borax.

The Making

Rucklin #1 seems problematic right from the start. The 24 parts borax simply seems odd...borax just makes a liquid and I couldnπt see why it would create a part of the alloy. I decided to melt the ammonium-chloride and the borax in a separate crucible into which I would pour the (en-sulphured) alloy of silver, copper & lead. I chose to do this in spite of the previous experiments wherein the sulphur was mixed in with the other powders either melted or not. I could find no sources with an explanation of what to do with such an odd recipe. I melted the silver, copper & the large amount of lead into the crucible and meanwhile melted the borax in a large crucible...I do not know whether Rucklin intended hydrous borax or an-hydrous borax. I used a hydrous borax. The small amount of ammonium-chloride produced a mild plume of grey smoke and when the solution was molten I added the molten alloy as well. The alloy swirled about, hardened and settled on the bottom of the crucible. I poured out the mixture into a steel plate and allowed it to cool. The niello sat in the middle of the black, glassy, friable remnant of the borax/ammonium-chloride mixture. The glass easily breaks and separates from the small button of niello and where it does separate there is a silver crystalline surface exposed on the niello.

The Application

I fluxed the sample with a dilute mixture of handy flux. I hammered the niello blob in an attempt to break it up. Instead it just forged flat like a normal metal ingot. I heated the sample and applied the niello in flat, cookie form...holding the piece of niello to the surface of the sample. The niello touched the hot metal and flashed a dark color across the surface of the sample. Un-like the normal flow of niello, this was purely a surface reaction on the sample. Soon the rest of the niello began to flow more like a normal application with the exception that the niello was more of a silvery, mercuric flow. When the sample cooled it had a rough surface with hard projections sticking out. These projections were not at all friable...the only way to remove them was to file them off. As I sanded down through the layer of niello I noticed that it was not at all black as in usual nielloes. When I finally got down to the parent metal it was obvious that this niello was extremely flawed...the relief is filled with a dull, brassy material not at all niello-like, perhaps mostly silver.

The Assessment

Rucklin #1 is a niello that I was unsure about from the beginning. I did not know where the large portion of borax was to figure into the formula. The only possibility I can come up with is that the sulphur, ammonium-chloride and borax all get put together (melted or in powder form) and the alloy is poured in as with other formulas. While that is more likely the solution it is not necessarily so...even with recipes that pre-mix the non-metal elements there is still no precedent for so much borax. I donπt know why the niello applied so poorly although Iπm not surprised that it did. The blob that formed in the borax seemed uniform when I inspected it. The forgeable quality of the original ingot is indicative of some anomaly. The content of silver, copper and lead should have made it friable like any other niello. Obviously something isnπt right with either my methods or the high content of borax in this recipe.



Rucklin #2:

1 part Silver,2 parts Copper,4 parts Lead,5 parts Sulphur

The Making

Rucklin #2 I made by melting together the silver & copper with an oxy-propane torch in a burno crucible. I added a pinch of borax at the point of melting and added the lead...muddled in the sulphur with an iron rod and poured after swirling a cinder into the crucible. I used one ounce as a part and ended up with one of the largest rods to date, nearly 2 1/2 feet long. Most of the pour looks good (clean breaks, shiny surfaces, rounded rod and etc...) The only anomaly was at the front of the pour where a small bead of silver appears to have crystallized...the rest of the pour seems void of any silver veins whatsoever.

The Application

I fluxed the sample with a 50/50 mix of handy flux & Prip's. I heated the sample from below with an acetylene flame and waited for the flux to clear. I applied the niello in rod form from a nice mid-section piece. It flowed clean & even...producing a flat surface across the top of the sample. This I deftly scraped with a steel bevel and sanded down with a 180 grit followed by a 220 grit. I finished the piece off with a bit of Scotch-brite.

The Assessment

There are only a few pits and holes in the sample. If I had burnished my niello '...as firmly as the work would seem to admit of,' while the sample was '...a little hotter than the hand could bear,' I would likely have stopped up '...certain bubble-holes.' (Cellini, p.9) I think these holes are the result of my own error as every other aspect of the niello making and application went off without any appartent problems. The niello, while slightly high in lead content, seems to work just fine according to the described methods.



Russian:

1.5 parts Silver,2.5 parts Copper,3.5 parts Lead,12 parts Sulphur

The Making

I made the Russian niello by melting the silver & copper together in a crucible, adding a pinch of borax at the point of melting and adding the lead. Swirling & stirring the alloy, I fused it well. I poured the niello into a container full of the 12 ounces of sulphur (unmelted.) The alloy lit the sulphur afire and I shook the container as several sources suggest. I left the mixture to do what it would and eventually the entire container was a pool of molten sulphur cooling off but never quite becoming solid. This mixture I subsequently reheated, burning off all of the sulphur and eventually remelting the alloy. I poured off the niello into the angle-iron and the results were very good to all appearances. The rod was thin and broke quite easily, the niello forming more 'beaded' sections than usual. The surface of the rod was deep and shiny.

The Application

I fluxed the sample with a dilute mixture of handy flux and heated from below with an acetylene torch. The flux soon became clear and the rod applied cleanly and evenly; filling every bit of the surface. Upon removal of the niello a relatively clear result soon surfaced. The niello had blurred the lines of the stamping slightly and showed a mild brownish color.

The Assessment

The niello fused quickly and well, the method of pouring the molten alloy into the dry sulphur seems to work just as well...perhaps a little more time-consuming than pre-melting the sulphur, but the result seems just as well. The only problem with the niello is the slight blurring of lines, probably due to an overheating of the sample (although I was not aware of such) or the quality of the stamp may have been such that it had a depressed area surrounding the actual mark and thus appears large or blurred.



Spon:

.5 parts Silver,1.5 parts Copper,2.75 parts Lead,27 parts Sulphur,2.75 parts Ammonium-Chloride

The Making

Sponπs formula comes down to us with his Workshop Receipts which I was unable to locate. My brief explanation comes from Herbert Maryonπs book Metalwork and Enameling. The formula calls for two crucibles: one filled with the sulphur and ammonium-chloride and the other where the metals are alloyed. I melted the silver & copper in a burno crucible with an oxy-propane torch and swirled, added the lead and stirred. I poured the molten alloy into the container with the unmelted sulphur/ammonium-chloride mixture. The second crucible immediately became afire with the heat of the molten metal and I shook the container. The mixture eventually cooled without melting the entire sulphur/ammonium-chloride powders. I plucked the niello nugget from the powder with a pair of tweezers and remelted the metal to burn off residual sulphur, then poured the niello into the angle-iron. This I did with dubious results. The rod has a depressed front and a surface similar to that of the Thai and Persian nielloes...rough and almost bubbly on top. There are some very minor silver veins running through the niello rod.

The Application

Spon reduces the mixture to powder and applies with a small amount of ammonium-chloride. Maryon states that this is the mixed with a '...solution of sal-ammoniac [ammonium-chloride] for use.' (p. 165) To me this implies a solution mixed with water. This is then heated until '...the composition solders the metal.' (ib.) I applied in the usual manner of rod & dilute handy flux with very poor results.

The Assessment

This is another example of a niello that is faulty for reasons I cannot understand. The sample shows a dark blob of niello that I left unfiled. Although it appears to have fused it demonstrates the nielloesπ unwillingness to flow. I took the sample to a dull red which is usually hot enough to cause the lead to disintegrate the silver. The method of pouring the alloy into the powder may have been faulty in that it is intended to be molten before the introduction of the alloy. I found no evidence in the text to suggest this and that is why I did not pre-melt the sulphur and ammonium-chloride. The rod itself, when poured, did exhibit symptoms that have come to mean bad niello: the bubbly surface, the collapsed surface and silver veins. It is possible that this pour was the cause of the faults in the niello...these traits seem to accompany the pour which occurs at too high of a temperature, although I was not aware of pouring at excessive heat. Generally I have also had poor results with any niello that includes ammonium-chloride.



Thai

1 part Silver,5 parts Copper,3 parts Lead, Sulphur in excess

The Making

I melted silver & copper with the oxy-propane torch in the crucible as usual, adding a touch of borax to insure complete melting. I swirled and added the lead, stirred and muddled in sulphur. I paused, swirled a cinder and poured. The rod cooled with nodules covering the surface. I filed these nodules to determine if they were hollow, silver, copper or niello. Oddly enough, each of these nodules seemed to be niello. Otherwise the rod broke clean and true, with black ends and no pliable sections. I then applied the niello to a sample with very poor results so I remelted the rod in an attempt to somehow re-alloy the stuff. The re-sulphured rod came out with the same nodules and suspecting those same to be either the cause or coinciding with some quality of the pour I recast it several times. Each time I received the same results and thus finally decided to apply the niello once again. The second sample came out with the same poor quality as the first.

The Application

The first sample I applied in powder form, making a paste with the 50/50 mix of handy and Prip's. The niello heated to a glowing red but refused to melt. By the time the sample became a dull red, the niello had begun to eat into the silver. The second sample proved to show the same trait for which I have no real explanation.

The Assessment

This niello seems for some reason determined to fail. The percentage of lead is relatively high but others higher in percentage have demonstrated better results. For the nodules I have no explanation. They may or may not imply or accompany some flaw in either the material or the process. As for the quality of the application I can only say that this niello is somehow flawed. Is there an aspect to the making that I am unaware? Some would say that the Thai have secrets which allow them to make an export industry in niello. There is speculation that they employ a reducing process which may or may not affect the quality of this particular formula.



Wilson:

6,2,1,10

The Making

The Wilson is the formula is specifically cited by Fike as the inspiration for his refined recipe. The '6,2,2,' of Fike honors the fact that he has added but one part to this existing formula, even though '3,1,1,' would be more proper. I therefore decided to manufacture Wilson in the manner of Fike to see if there was an immediately discernable difference. I melted the silver & copper with my oxy-propane torch, swirled the two metals and added a pinch of borax just prior to the lead. Swirling the three with the accompanying sway I paused to heap in a tablespoon of sulphur which I muddled down into the burning alloy. Repeating this step twice more I allowed for the cinder to form and poured down the angle-iron.

The Application

The rod shone forth true and dark; clear and straight; shiny and crisp. I applied in rod form with an acetylene torch and dilute handy flux. I obtained good results as can be seen on the sample.

The Assessment

Wilsonπs formula is an excellent one and works well with the modern metalsmithπs most available methods. The flow was even and quick and went off without a hitch.



Conclusion

In the process of making and applying these many nielloes I have encountered certain difficulties and reached several general conclusions. Some of these conjectures concern actual formulae and others concern methodology. Most of these speculations have at least one contradictory result and some are quite intuitive in nature. I have no absolute conclusions except that with practise one may become better at the art of Niello. Concerning the formulae themselves, I have enjoyed the least success with those recipes high in lead content. The recipes Persian #1 and Thai in particular, both with very high lead to silver ratios, exhibited similar behaviors. Both produced pours with uneven surfaces which were U-shaped toward the front. Unlike Persian #1, the Thai recipe produced unexplainable nodules but both recipes refused to melt, fuse or flow upon application. I had originally predicted that a niello high in lead would have a better flow and a lower melting point but in fact, neither of these formulae had either quality. I also had poor results with any recipe including ammonium-chloride. Rucklin #1, Persian #2 and Spon all included various degrees of ammonium-chloride solutions. All provided poor results. Further exploration might reveal if a change in methods would demonstrate better applications. On the other hand, I had success with a number of nielloes: Cellini (manufactured according to the same), Fike and Wilson in particular. Most of these formulae have a higher silver to lead ratio. Cellini is an exception but I also had difficulties with his recipe when made according to easier, modern methods. I generally found that Fikeπs method of making niello tended to be the most successful and least wasteful method. Fike 'muddles' in his sulphur whereas Theophilus and others pour the molten alloy into a container already full of sulphur. While the pouring method seems to work just as well, it requires more sulphur than Fikeπs method. There is also either excess sulphur to burn off or waste in the rather unpleasant form of molten sulphur. I had better results with those recipes that call for pre-melting the sulphur than those that did not. Celliniπs method is by far the most wasteful and dangerous of the several methods attempted during this thesis. Not only does Cellini waste sulphur by filling the flasks 'half-full,' but the flasks themselves are wasted in the process. The danger involved in handling (and agitating!) hot flasks with molten compounds of metal and sulphur seems excessive; although it is exciting. Considering Theophilusπ methods I cannot say that Cellini was limited to the technology of the day. I must therefore state that even Cellini could have devised a better method. During the course of this thesis I had also hoped to simply gain more skill in the practise of niello. I have learned to observe several events that I believe affect the success of a niello venture. Were I to do this thesis again entirely from the start I have no doubt that I would immediately notice a marked increase in the quality of all the experiments. I do not believe that this has adversely affected the general results of this project, merely that all the nielloes would benefit from a greater experience in the medium.

When making niello, there are many important things to observe, avoid and encourage. It is important to stir the initial alloy that consists of only silver and copper as I have noticed that the surface of the alloy may appear completely molten and fluid while the bottom is not. Upon adding the sulphur one must be certain that there is not formed a crust atop the alloy. This crust can be extremely difficult to break and it usually causes the alloy underneath to cool and solidify, melting the crust repeatedly keeps the niello unnecessarily hot for too long. The crust seems more likely to form when dealing with a larger volume of niello, possibly because it requires more heat than a smaller volume. The last and most important event to observe carefully is the actual pour. Phillip Fike has described the moment of the pour as '...indescribeable,' (Fike, p.5) and I agree. My initial pours were all made at too high a temperature, which is the cause of silver veins running through the center of a pour. In the case of a cookie pour the silver forms a small button in the center of the remaining alloy. The niello must be heated appropriately to both keep it fluid and burn off excess sulphur. It must not solidify before the pour. However, as the niello must not be heated too high, care is needed. The pour itself takes place just as the niello begins to solidify and this is the cause of Fike's 'cinder'. Just as he intuitively believes that this 'cinder' is beneficial so have I also come to believe. The signs of a good pour are obvious soon after it solidifies. A good pour exhibits a smooth, shiny, black surface and starts to bend upward at the ends as it cools. When broken the rod should snap cleanly, with no malleability. Upon closer inspection the broken ends should show a minute, crystalline surface that is evenly black. The rod should not have a portion larger than 10 or 20% collapsed at the front of the pour and as it cools it should glow uniformly. Any abnormalities are likely indicative of a bad pour. (Such an anomaly was the nodules on the Thai niello.) When applying niello I have noticed little difference in the effect of fluxes. Prip's and Handy flux both seem to work well. An excess of flux creates flux glass which will form holes and curved pits if not removed, and diluting the fluxes helps alleviate this problem. A sure sign of a bad niello is that it does not immediately melt and flow across the surface of the base metal. It should flow quickly and evenly. It should not be heated beyond this point or silver is likely to recrystallize. Sometimes it is necessary to heat not only the base metal, but the niello as well and I have had no adverse effects as a result of this as long as I did not heat the niello too much. It is difficult to qualify much of the experience gained herein. I know what '...heating too much,' means but I cannot convey exactly what that is. Niello is finicky and troublesome. I believe that is very much a reason it has fallen out of common use. Even after all of the experience gained through this thesis I am not completely confident I will always enjoy success when employing this technique. There is still much to be learned and this thesis has only grazed the very surface. There are in fact several recipes I did not have the opportunity to experiment with. Bolas #1 is made of 2 parts antimony sulphide, one part lead sulphide and 8 parts sulphur. Bolas #2 calls for antimony and Augsberg #2 is a mercury amalgam! I could not obtain antimony or lead sulphide for the first two recipes and owing to the danger presented by the Augsberg recipe I opted to leave them out. One can easily see that of niello '...this art, the which in truth would engage a man's whole energies, and make him practise no other art at all,' leaves much to be explored.

Bibliography

Cellini, Benvenuto. Treatises on the Arts of Goldsmithing and Sculpture. (Translated by C.R. Ashbee.) London: Edward Arnold, 1898; New York: Dover Publications Inc., 1967.

Fike, Phillip. Niello Workshop Handout., Workshop at the Maine College of Art, November, 1990.

Maryon, Herbert, O.B.E., F.S.A. Metalwork and Enamelling. 5th ed. New York: Dover Publications Inc., 1971.

Theophilus. On Divers Arts. (Translated by John Hawthorne and Cyril Smith.) New York: Dover Publications Inc., 1979.

Untracht, Oppi. Jewelry Concepts and Technology. New York: Doubleday, 1985.

von Nuemann, Robert. The Design and Creation of Jewelry. Revised. Radnor, PA., Chilton Book Company, 1972.

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