Low fire glazes must be able to pass the bubbles their bodies generate (or clouds of micro-bubbles will turn them white). This cone 04 flow tester makes it clear that although 3825B has a higher melt fluidity (it has flowed off onto the tile, A has not). And it has a much higher surface tension. How do I know that? The flow meets the runway at a perpendicular angle (even less), it is long and narrow and it is white (full of entrained micro-bubbles). Notice that A meanders down the runway, a broad, flat and relatively clear river. Low fire glazes must pass many more bubbles than their high temperature counterparts, the low surface tension of A aids that. A is Amaco LG-10. B is Crysanthos SG213 (Spectrum 700 behaves similar to SG13, although flowing less). However they all dry very slowly. Watch for a post on G2931J, a Ulexite/Frit-based recipe that works like A but dries on dipped ware in seconds (rather than minutes).
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