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These were 10g balls melted using our GBMF test. Frit 3602 is lead bisilicate. But it got "smoked" by the Fusion FZ-16 high-zinc, high-boron zero-alumina! Maybe you always thought lead was the best melter. That it produced the most transparent, crystal-clear glass. But that is not what we see here. That being said, notice the lead is not crazing but the FZ-16 is crazing badly, that is a problem for many applications. Notice something else: Each frit has a distinctive melt fingerprint that makes it recognizable in tests like this.
This demonstrates the amazing melt behaviour of lead-as-a-flux for ceramic glazes. Not only does it melt early, but it softens slowly over a 300F range of temperatures before it goes off the end of the runway on this GLFL test. Then, when fired 200F hotter than that, it remains a stable, clear and uncrazed glass. Beginning around 1750F, this becomes a transparent glaze, by itself.
This melt flow tester demonstrates the beautiful crystal-clear glass this zinc frit creates by 1700F. It fits this porcelain without crazing, even though very thick and high in sodium (the high zinc and boron are countering it to keep the thermal expansion down). It runs off the end of the runway around 1600F on this GLFL test, rivaling lead bisilicate. This is a more concentrated boron source than even Gerstley Borate. Everything about this material screams “ultra gloss”, what a material to build a fluid-melt reactive super-glaze on!
Tests |
Glaze Melt Fluidity - Ball Test
A test where a 10-gram ball of dried glaze is fired on a porcelain tile to study its melt flow, surface character, bubble retention and surface tension. |
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Materials |
Frit B325
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Frit LA-300
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Ferro Frit 3249
A magnesia borosilicate frit having very low thermal expansion and melting point. Invaluable in pottery as to increase the MgO in glazes to prevent crazing. |
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Ferro Frit 3195
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Ferro Frit 3124
A commonly available borosilicate frit is high in calcium. |
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Ferro Frit 3110
High sodium, high thermal expansion low boron frit. A super-feldspar in clay bodies. |
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Fusion Frit F-524
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Fusion Frit F-75
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Fusion Frit F-69
A magnesia borosilicate frit having very low thermal expansion and melting point. Commonly used as a substitute for Ferro frit 3249. |
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Ferro Frit 3134
A frit with 23% B2O3. The most common of frits used in pottery in North America. Around the world, other companies make frits of equivalent chemistry. |
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Fusion Frit FZ-164
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Fusion Frit F-15
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Fusion Frit F-38
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Ferro Frit 3602
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Fusion Frit FZ-16
The champion in our frit melt-off competitition. This frit showcases the amazing fluxing power of boron and zinc working together. It is 15.5% ZnO. |
Temperatures | Comparison of frit melts at 1700F (926-) |
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