|Monthly Tech-Tip |
Fired at 350F/hr to 1700F and held for 15 minutes. 3110 is finally starting to move. 3134 also (being full of bubbles). Gerstley Borate has turned almost transparent (because the Colemanite portion of it is now melting). 3195 is looking very well behaved compared to most others, forming a bubble free glass of high surface tension (F15 and F524 are starting to do the same).
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.
These were 10g balls melted using our GBMF test, the tile they are being fired on is a grogged stoneware clay. A few of the more interesting ones here are frit 3470 lead zinc, 3185 super high boron, CC257 high barium, FR003 high alkali and F49 and FR001 opacifieds. Notice how early and vigorously some are melting. But notice 557 and 556, they aren’t doing anything - that is not by accident. These are fast-fire frits, they are designed to melt later and more quickly. This is only 1700F, since no one fires this low it makes sense that if a glaze has not started melting it will be able to pass escaping gases of decomposition. This avoids the bubbles and surface defects these cause, as 3185, CC257 and 3470 are already demonstrating. What about FR002, FR002 and 3565, they are melting and look fine? They have higher surface tension and much less contact with the body generating the gases.
|By Tony Hansen|
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