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Replace talc with a nepheline syenite:dolomite mix in low fire white clay bodies
G1916Q and G3879 and low-expansion versions of each. These are excellent bases and enable expansion-adjustability (by blending).
Cone 05+ Expansion Adjustable Gloss Base
Total:100.00
Notes *Although similar to the previous G1916M, this recipe provides greater thermal expansion adjustability. It combines a middle-of-the-road thermal expansion frit with a very low and very high expansion frit (they cancel each other out but increase gloss of the otherwise silky Frit 3195). The frits in this recipe are common (the 3249 less so but it deserves to be common because of its utility). We adjusted this in a later version, G1916QL1, it employs a kaolin for better clarity and more frit 3249 for glaze fit on more bodies. Pictures G1916Q at Cone 01 on 3D+iron Very nice results on L3724E red body at cone 01. Piece is very strong. 1916J and Q fired to 1450F These glazes are starting to melt, the surface having reached the consistency of a porcelain and have densitfied to very low porosity. Notice the iron in the ball clay really shows up at this stage (it will be less evident later). G1916Q Cone 04 using 04DSSC schedule Counterclockwise: L212, Raku, Buffstone, L213, L210, L215 G1916Q and J fired 1650-2000F Ten-gram balls melted and flattened as they fired. They soften over a wide range, starting well below cone 010! At 1650F carbon material is still visible (even though the glaze has lost 2% of its weight to this point), it is likely the source of the micro-bubbles that completely opacify the matrix even at 1950F (cone 04). This is an 85% fritted glaze, yet it still has carbon; think of what a raw glaze might have! Of course, this is a thick layer, so the bubbles are expected. But they still can be an issue on a piece of ware. So to get the most transparent possible result it is wise to fire tests to find the point where the glaze starts to soften (1450F in this case), then soak the kiln just below that (on the way up) to fire away as much of the carbon as possible. Success with cyrstal clear glaze cone 03 Uses Cone 03 soak-soak-slow cool schedule. G1916Q on L215, L212, L210, L213, Buffstone at cone 03 All exited from the klin without crazing. The L215, L213, L210 and L212 samples subsequently survived a 300F/Icewater test without crazing, but the Buffstone did not. The L213 would not likely survive a cold-to-hot test without shivering. 1916Q cone 04, 03 Both were slow cooled. While the cone 04 version is glassy and ultra-gloss, it has significant clouding of micro-bubbles. The cone 03 version, right, is completely transparent. G1916Q on L210 fired at cone 04 Has survived for a year without crazing. G1916Q+2%Iron on L212 talc body fired at cone 05 This will likely shiver over time. But the speckle that happens on white bodies is clearly visible. G1916Q applied thickly on L215 fired cone 04 No crazing after 2 months. G1916Q on L4170 cone 04 Thin application is clearly the way to get the best transparent. The glaze eventually craze where application is thicker. XML (to paste into Insight) <?xml version="1.0"?> <recipes version="1.0" encoding="UTF-8"> <recipe name="Cone 05+ Expansion Adjustable Gloss Base" id="56565" key="yPamv6HE" date="2023-10-31" codenum="G1916Q"> <recipelines> <recipeline material="Ferro Frit 3195" amount="65.000" tolerance=""/> <recipeline material="Ferro Frit 3110" amount="10.000" tolerance=""/> <recipeline material="Ferro Frit 3249" amount="10.000" tolerance=""/> <recipeline material="No. 5 Ball Clay" amount="15.000" tolerance=""/> </recipelines> </recipe> </recipes> Born: 2014-03-04, Modified: 2023-10-31 22:20:07 |
Cone 05+ Lower Expansion glaze
Total:100.00 Auto Unity Formula
Notes *This is a much-lower-thermal-expansion version of our standard G1916Q low fire clear recipe (which was delay-crazing on the L4410C, L4410K, L4410L cone 04 test bodies). The lower expansion was achieved by eliminating all high-expansion 3110 and more than doubling the low-expansion 3249. This now shivers on our L4170B terra cotta (use the G1916Q for it). Pictures 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). 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. Spectrum 705 Black, G1916QL clear on L4410K at cone 03 The quality of this piece is amazing! The evenness of coverage that can be achieved with brush-on glazes is impressive. This was my favourite coffee mug. However it did finally craze after about 2 weeks of use (that motivated the recipe change to G1916QL1). 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. G1916QL1 on medium temperature porcelains Clockwise from top left: L213, M370, P300, Polar Ice Cost comparison vs. Spectrum 700 Clear G1916QL1 on L215 - more than a year old This was done as a brushing version of this recipe. 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 05+ Lower Expansion glaze" id="202545" key="hBLp9xQc" date="2024-03-29" codenum="G1916QL1"> <recipelines> <recipeline material="Ferro Frit 3195" amount="60.000" tolerance=""/> <recipeline material="Ferro Frit 3249" amount="25.000" tolerance=""/> <recipeline material="New Zealand or Grolleg kaolin" lookup="Grolleg Kaolin" amount="10.000" tolerance=""/> <recipeline material="45 micron Silica" lookup="Silica" amount="5.000" tolerance=""/> </recipelines> </recipe> </recipes> Born: 2014-03-04, Modified: 2024-03-29 18:06:15 |
Cone 05+ Low Expansion Transparent glaze
Total:100.00 Auto Unity Formula
Notes *This is a lower-thermal-expansion version of our standard G1916Q low fire clear recipe (which was delay-crazing on the L4410C at cone 04 clay). The 15% ball clay impart good slurry properties (to enable getting it on evenly if a thixotropic consistency can be achieved). Pictures G1916QL on L3685Z2 on L4170B at Cone 04, 02 After months both are still uncrazed. But some shivering on the rim of cone 02 piece. L4410K with G3879G1 and G1916QL at cone 04 Both are crystal clear, results are stunning! Both the G3879G1 and G1916QL glazes held up well in my kitchen at home. For a while. The G1916QL on crazed after a couple of weeks. The G1 crazed after about a month. Spectrum 705 Black, G1916QL clear on L4410K at cone 03 The quality of this piece is amazing! The evenness of coverage that can be achieved with brush-on glazes is impressive. This was my favourite coffee mug. However it did finally craze after about 2 weeks of use (that motivated the recipe change to G1916QL1). 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. G1916QL on L4410J - 2 months, no crazing, brilliant surface L4410L with G1916Q, G1916QL and G3879 - Cone 04 Only the G1916Q is crazing after several months. XML (to paste into Insight) <?xml version="1.0"?> <recipes version="1.0" encoding="UTF-8"> <recipe name="Cone 05+ Low Expansion Transparent glaze" id="192370" key="Z9CzkjbQ" date="2024-03-25" codenum="G1916QL"> <recipelines> <recipeline material="Ferro Frit 3195" amount="65.000" tolerance=""/> <recipeline material="Ferro Frit 3249" amount="20.000" tolerance=""/> <recipeline material="No. 5 Ball Clay" amount="15.000" tolerance=""/> </recipelines> </recipe> </recipes> Born: 2014-03-04, Modified: 2024-03-25 23:56:45 |
Cone 04+ UltraClear Glossy Base
Total:1,025.00 Auto Unity Formula
Notes *We developed this for cone 06-04 to fit many clay bodies (without crazing), melt well at cone 05 and produce a more transparent glaze (rather than the amber of G2931K and G1916Q). The frit F-524 in this recipe is less common among potters but common in industry, it is high quality. We later adjusted this recipe to produce variations (e.g. with whiter kaolin, more of the frit F-69 to get a lower thermal expansion). Pictures G3879 Clear glaze on Plainsman L211 - Cone 04 Glossy, crystal clear, no crazing! And this is a 42 mesh body containing zero talc. Melt fluidity comparison with #1 commercial clear We tested half-a-dozen commercial clears and found G3859 to be the best all-around one. This one has a very similar melt fluidity. G3879 on Plainsman L210, L215 at cone 04 These are 42 mesh low fire bodies. They normally have issues with pinholing but using this glaze the results are stunning. The L210 contains no talc, the L215 has 10%, yet this glaze does not craze on either one (over time it shivers on the L215). G3879 on SIAL 25F, Plainsman J2, L4170 TerraCotta These are very different bodies. The leftmost contains talc to raise the thermal expanison to help prevent crazing with commercial glazes. The center one contains nepheline syenite (for the same purpose). The terra cotta on the right is just Redart and ball clay. This glaze fits are all three! Sial 10F, 25F with G3879 clear glaze at cone 03 Tile like these were done on a variety of bodies and fired at different temperatures. After a year: G3879 Clear on L4170 TerraCotta Casting The clear glaze is G3879. The white on the outside of the one on the left has 10% added zircopax. The overglaze colors are Spectrum Majolica colors. G3879 with 5% Tin Oxide on SIAL 10F When mixing Tin (as an opacifer), it is very important to mix it well. The one on the left was mixed poorly (at high speed with my propeller mixer but not for long enough). The one on the right was mixed much better and so produces better opacity. Tin is expensive so this is important. G3879 on Plainsman Buffstone - cone 03 Buffstone is an entry-level low-price body not intended to fit commercial glazes. Yet this glaze fits at cone 03 (still fitting after a year)! And without any surface defects. G3879 Zircon White on SIAL 25F, 10F - cone 03 10% zircopax has been added. It is melting well so the percentage could be increased for great opacity on red burning bodies. G3879 at cone 1 on SIAL 10F, 25F Crystal clear, no running. Perfect! GBMF test on G3879 at cone 1 It is not running and flowing nearly as much as expected. The melt surface tension holds it in place, so it should be able to fire to cone 2 and beyond. G3879 on terra cotta at cone 04, 02, 1 This is on the L4170 body, it is a lighter firing product, 25F, from SIAL. After use on various bodies, it was clear that fit at cone 03 is better than at 04 and much better than 06. G1916M, G3879, G2931K on L215 - Thick Thickly applied encourage poor fit to show up. L213 with G3879 glaze at cone 04 Survived 325F:IceWater test with almost no crazing. However there was a little shivering on the rim after a month. Another mug had no crazing on the inside after several months. G3879 on L4115J2 buff body at cone 04 Glaze is ultra clear. G3879 on SIAL 10F at cone 02 No crazing after several months. Flawless service. Variations B - Tin White XML (to paste into Insight) <?xml version="1.0"?> <recipes version="1.0" encoding="UTF-8"> <recipe name="Cone 04+ UltraClear Glossy Base" id="154451" key="X4ER8CxL" date="2023-06-16" codenum="G3879"> <recipelines> <recipeline material="Fusion Frit F-524" amount="850.000" tolerance=""/> <recipeline material="Fusion Frit F-69" amount="40.000" tolerance=""/> <recipeline material="EPK" amount="90.000" tolerance=""/> <recipeline material="Silica" amount="45.000" tolerance=""/> </recipelines> </recipe> </recipes> Born: 2019-04-15, Modified: 2023-06-16 11:32:20 |
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="iYjz4NAv" 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 |