
Ancient Egyptians used a variation of this decoration technique as did the ancient Romans. During the Roman occupation and migration period niello spread throughout Europe, as can be seen from Anglo-Saxon finds in Britain, as well as in Eastern Europe. The Byzantines also had a great love for this technique. At the dawn of the Gothic period, niello was revived in the Rheno-Mosanarea of Germany and the low countries. It reached its height during the Renaissance when great masters such as Francesco Francia and Maso Finiguerra executed niello works to perfection. At the end of the 1700s, this method of surface decoration was revived again and remained popular, to some extent, during the 1800s and the early 1900s. The town of Tula in Russia became especially famous for its niello work, which accounts for the alternate name of Tula silver. Around 1900 most niello work came from this town, some 200 km. south of Moscow,where it was applied to watchcases, objects de virtu, jewellery, guns, and tableware.

Niello is commonly applied to silver due to the high contrast between silver and black niello. It was also applied to gold, especially in Byzantium. Some sources report that it does not hold well on copper alloys due to its lead content, but that only applies to the more modern versions of niello as the lead was probably added to the mixture as of the late Byzantine era around the 900s.
François Schweizer analysed Byzantine niello works from different periods and concluded that there were 3 different mixtures used during the evolution of the Byzantine arts,which he categorized:
-
Type I: silver sulphide (monometallic)
-
Type II: silver-copper sulphide (bimetallic)
-
Type III: silver-copper-lead sulphide (trimetallic)
According to Schweizer, the lead was added in the 900s to create a lower melting point for the niello mixture, making it easier to work with. The earliest text on niello, by Pliny the Elder in the 1st century AD, confirms this later addition of lead because it does not mention lead at all, merely the type II niello composed of copper, silver, and sulphur.
The next recording of niello work is from the 1100s by Theophilus where lead is added to the recipe. Cellini used this formulation in the 1500s and his recipe, with some variations, is still used today. Niello also developed in many other countries outside Europe, possibly the most prominent being Thailand where it is still widely used.
Technique
Through engraving, etching, chiselling embossing or another method, a design is created on the work which will hold the niello.The methods used in niello are similar to émail champlevé and émail de taille d’epargné, although most other enamelling techniques can be used as well. Due to these similarities, niello is sometimes misnamed black enamel.

After thoroughly cleaning the object, the wet niello is applied similarly to the enamel. Due to the shrinkage, enough of it must be applied, preferably in hillocks. The wet paste is now left to dry and then fired in an oven. The niello will fuse with the metal base of the object. It may be necessary to repeat this procedure a few times to evenly fill the entire area, but it is best to do it correctly the first time. As an alternative, the object could be fired from below with a flame, which takes extra skill and practice as it could burn both the niello and the metal. The lead will corrode the silver or gold at high temperatures. Sometimes pits from air bubbles are present on the surface of the niello after firing. These pits can be pressed out while the surface is still hot or smoothed out later with a steel burnished.

The Fuller Brooch, Silver and Niello. Anglo-Saxon, 9th Century.

Recipes
Compose the niello in this manner; take pure silver and divide it into equal parts, adding to it a third part of pure copper, and taking yellow sulphur, break it very small and when you have liquefied the silver with the copper, stir it evenly with charcoal, and instantly pour into it lead and sulphur.
|
Silver |
Copper |
Lead |
Sulphur |
Other |
Pliny |
1 |
0.33 |
None |
1 |
- |
Theophilus |
2 |
1 |
0.05 |
In Excess |
- |
Cellini |
1 |
2 |
3 |
In Excess |
- |
Kunz |
Unknown |
Unknown |
Unknown |
Unknown |
Antimony |
Brepohl |
2 |
1 |
1 |
In Excess |
- |
Partially after Untracht
Repairs
Due to the various components of niello, the black tones may differ from maker to maker. It is the amount of sulphur added that usually dictates the tone. Tone can also be influenced by the composition of the silver copper-lead alloy. When repairs are done on the piece the same recipe needs to be used or there may be a very noticeable tonal difference which can appear worse than the original fault. To avoid tonal variation, whole sections should be scraped away and redone while covering the other parts with a heat protector. Either way, this is a job for specialists.
Due to the various components of niello, the black tones may differ from maker to maker. It is the amount of sulphur added that usually dictates the tone. Tone can also be influenced by the composition of the silver copper-lead alloy. When repairs are done on the piece the same recipe needs to be used or there may be a very noticeable tonal difference which can appear worse than the original fault. To avoid tonal variation, whole sections should be scraped away and redone while covering the other parts with a heat protector. Either way, this is a job for specialists.
Caution
The lead and sulphur contents of the niello are highly toxic and safety precautions should be taken while working with it. Good ventilation is especially important. Lead corrodes precious metals at high temperatures and all tools, files, scrapers, and sandpaper, used on lead should be stored separately in the workshop. The smallest residue of lead could transfer from the tools to a precious metal item and ruin your work, not to mention your health.