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Bismuth Subnitrate

Oxide Analysis Formula
Bi2O3 76.40% 1.00
LOI 23.60%n/a
Oxide Weight 465.96
Formula Weight 609.90


Bismuth nitrate is obtained from metallic bismuth and is soluble in acids but insoluble in water. Impurities are arsenic, lead and silver carbonates.

It gives a pearly luster to glazes and glasses, especially in reduction firing (light reduction). It is an ingredient in luster colors. It is a very very strong flux. Bismuth oxide contains 100% of the oxide while this is only 75%.

Related Information

Examples of bismuth glass compositions and their expansions, softening points

Using bismuth it is possible to create very low melting glasses (or glazes). But a very high percentage is required. And bismuth is expensive.

What Bismuth Subnitrate does between 1100-1250F

Bismuth Subnitrate melting at 1300F

I did this using our standard melt flow tester. I prepared 10-gram balls by mixing the bismuth subnitrate powder with 1% CMC gum (like what we do for the GBMF test). These balls were fired in an electric oxidation kiln to 1100F, 1200F, 1250F and 1300F (593-704C). It is not difficult to see why this is a potential ingredient in low temperature frits. Does anyone know why it burns yellow?


Hazards Bismuth Trioxide Toxicology
Typecodes Generic Material
Generic materials are those with no brand name. Normally they are theoretical, the chemistry portrays what a specimen would be if it had no contamination. Generic materials are helpful in educational situations where students need to study material theory (later they graduate to dealing with real world materials). They are also helpful where the chemistry of an actual material is not known. Often the accuracy of calculations is sufficient using generic materials.
Typecodes Flux Source
Materials that source Na2O, K2O, Li2O, CaO, MgO and other fluxes but are not feldspars or frits. Remember that materials can be flux sources but also perform many other roles. For example, talc is a flux in high temperature glazes, but a matting agent in low temperatures ones. It can also be a flux, a filler and an expansion increaser in bodies.
Oxides Bi2O3 - Bismuth Oxide
Temperatures Bismuth Subnitrate decomposes (260-)
Materials Bismuth Oxide
Bismuth is a very strong flux that enables glass melts lower than any other, even lead. However its price limits its utility to highly specialized products.
Materials Fusion Frit FZ-915
Bismuth Oxynitrate on Wikipedia


Frit Softening Point 260C D
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