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It is likley to be a combination of glaze chemistry, thorough melting, slurry preparation, application thickness, firing, choice of clay body.
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="Ghk3Tamy" 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 |
Cone 04+ UltraClear Glossy Base
Total:101.00 Auto Unity Formula
Notes *This adds more SiO2, less Al2O3 and less B2O3 seeking fewer microbubbles than G3879C. Pictures Three clear glazes on L215 at cone 04 ![]() G3879D - Good transparency but shivering enough that it is hazardous to pick up the mug for fear of glass slivers XML (to paste into Insight) <?xml version="1.0"?> <recipes version="1.0" encoding="UTF-8"> <recipe name="Cone 04+ UltraClear Glossy Base" id="228221" key="CaYQqkdf" date="2022-12-19" codenum="G3879E"> <recipelines> <recipeline material="Fusion Frit F-524" amount="85.000" tolerance=""/> <recipeline material="Ferro Frit 3110" amount="5.000" tolerance=""/> <recipeline material="Silica" amount="10.000" tolerance=""/> <recipeline material="VeeGum" amount="1.000" tolerance=""/> </recipelines> </recipe> </recipes> Born: 2019-04-15, Modified: 2022-12-19 22:20:16 |
Cone 04+ UltraClear Glossy Base
Total:100.00 Auto Unity Formula
Notes *This variation seek better melting to be ultragloss. Both 3110 and 3249 should help with melting the frit 524 better. Pictures XML (to paste into Insight) <?xml version="1.0"?> <recipes version="1.0" encoding="UTF-8"> <recipe name="Cone 04+ UltraClear Glossy Base" id="228330" key="X3dChkcQ" date="2022-12-19" codenum="G3879F1"> <recipelines> <recipeline material="Fusion Frit F-524" amount="65.000" tolerance=""/> <recipeline material="Old Hickory #5 Ball Clay" amount="15.000" tolerance=""/> <recipeline material="Fusion Frit F-75" amount="10.000" tolerance=""/> <recipeline material="Fusion Frit F-69" amount="10.000" tolerance=""/> </recipelines> </recipe> </recipes> Born: 2019-04-15, Modified: 2022-12-19 22:25:45 |