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This is about showing that glazes based on lead bisilicate frits can be safe and are unmatched in gloss, color hosting and transparency.
Lead Bisilicate Glaze
Total:100.00 Notes *This glaze is part of my efforts to demonstrate the a lead bisilicate frit can be used to make a transparent glaze impossible by any other means. And it can be safe. Pictures Boron vs Lead glaze on l215 The mug on the left is a brush-on version of a G3879C, a boron-based clear glaze for cone 05. Three coats were applied and the often-encountered clouding occurred. The one on the right is an 85:15 lead bisilicate:kaolin mix. Three coats were also applied (by brushing also). G3971 Lead Bisilicate Glaze on L215 Cone 04 Untitled G3971 Lead Bisilicate on various clays Crazing on Buffstone G3971B Lead Bisilicate Glaze passes lead check test URLs XML (to paste into Insight) <?xml version="1.0"?> <recipes version="1.0" encoding="UTF-8"> <recipe name="Lead Bisilicate Glaze" id="230431" key="gmtAYJ8s" date="2024-03-14" codenum="G3971"> <recipelines> <recipeline material="Frit B350" amount="85.000" tolerance=""/> <recipeline material="EPK" amount="15.000" tolerance=""/> </recipelines> </recipe> </recipes> Born: 2023-01-05, Modified: 2024-03-14 21:13:13 |
Cone 04 UltraClear Low-Expansion
Total:1,025.00 Auto Unity Formula
Notes *An adjusted version of G3879 to reduce thermal expansion. It switches the silica to 45 micron (325 mesh) for better dissolution in the melt. And it increases the frit low-expansion F-69 (the Fusion equivalent of Ferro 3249) at the expense of F-524. Pictures G3879C is firing much whiter, why? Cone 04. All three clear glazes are on the same body. Left to right: Amaco LG10, G3879C recipe, Crysanthos SG213. The middle one employs Fusion Frit F-524, it is more expensive. But look at the benefit: It fires much more transparent so the piece is much whiter. And it is not crazing or pin holing. And it is glossier. G3879C, G1916Q, G1916QL1 on L213 Cone 04 The move from ball clay to New Zealand kaolin (centre mug vs right mug) greatly improves the clarity (because of the reduction in iron and titanium). G3879C vs. G1916QL on L4410K low fire white The iron from the ball clay is the reason the glaze on the right is off-white. Cone 04 G1916QL1 vs G3879C melt flow comparison G1916QL1 is more melt fluid so it is likely useful before cone 04. But G3879C is also very fluid (it also has a higher surface tension). Both are producing textbook high quality flows. G3879C, G1916QL1 on L4410L Bisque 1800 glaze cone 04 No crazing after weeks of use, ultragloss. G1916QL1. G3879C, G3879G1 on L213 tiles - Cone 04 These are all craze-free after several months. G3879C on L4410P dolomite body at cone 04 The outside glaze is Spectrum 336. The G3879C is our recipe, a base transparent that we have been tuning to reduce the thermal expansion as much as possible to fit our 50:40:10 BallClay:Dolomite:Nepheline body. The result is glaze compression, it is now under enough compression on the inside of this piece that it is forcing it apart. G3879C on L215, Buffstone at cone 02 Clouding badly on terra cotta, better on the white body. G3879C on L4170B at cone 04 with L3685Z6 engobe No crazing after six months or more. Testdata LDW - LOI/Density/Water Content
XML (to paste into Insight) <?xml version="1.0"?> <recipes version="1.0" encoding="UTF-8"> <recipe name="Cone 04 UltraClear Low-Expansion" id="202474" key="oGcjFbuo" date="2022-12-19" codenum="G3879C"> <recipelines> <recipeline material="Fusion Frit F-524" amount="750.000" tolerance=""/> <recipeline material="Fusion Frit F-69" amount="140.000" tolerance=""/> <recipeline material="New Zealand or Grolleg kaolin" lookup="Grolleg Kaolin" amount="90.000" tolerance=""/> <recipeline material="Silica 45 micron" lookup="Silica" amount="45.000" tolerance=""/> </recipelines> </recipe> </recipes> Born: 2019-04-15, Modified: 2022-12-19 22:22:22 |
Spectrum Clear 700 Dipping Glaze
Notes *Spectrum mix #37779 Pictures Spectrum 700 on 6318 Terrastone at cone 03 It is on too thick on the mugs, goes cloudy. Spectrum 700 Clear (left) vs. G2931B (right). The spectrum glaze is on too thick and is clouding. The Ulexite glaze looks very good beside it and has better application properites. Cone 2 (left> vs cone 06 Spectrum 700 with underglazes P6318 Terrastone body. 700 Clear on P6318 cone 2 vs 06 The 06 is defect and bubble free. Cone 2 has significant micro pinholes. Precipitate in Spectrum Clear 700 XML (to paste into Insight) Born: 2016-01-13, Modified: 2016-08-23 13:15:26 |