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Cone 6 Fluid Melt Glaze Project 2015 - Stage 1 - Compare Popular Recipes
This page documents my efforts to develop a cone 6 transparent glaze that is high gloss and fluid melting but resists crazing and is durable. G3806D lower COE is latest.
High Melt Fluidity Cone 6 Clear Glaze
Most functional ceramic glazes can be distilled down to two parts: a clear matte or glossy base plus opacifiers and colorants. It is always best to use a base having plenty of SiO2 and Al2O3 to produce a glass that is resistant to leaching and wear. G2926B is an excellent example, it produces a glassy smooth and durable glaze. We use it whenever possible. However for reactive visual effects, a fluid melt base is needed and that means sacrificing some Al2O3/SiO2 (and the associated durability).
Campana Cone 6 Transparent Glaze
3134, Spodumene, Zinc
Auto Unity Formula
This is a popular fluid-melt cone 6 base recipe. We first compared it with 4 others in an effort to produce a fluid-melt, super-gloss, low-expansion transparent base. This appears to be the 20x5 recipe with Custer feldspar switched for a mix of zinc and spodumene (combining the power of lithia, zinc and boron fluxes to achieve a very low calculated thermal expansion, it does not craze on any of the bodies tested). Interestingly, because it has lots of melt fluidity it could likely accept more Al2O3 and SiO2 and yet still fire glossy (meaning the expansion could be taken still lower).
Compared with G2926B
These are 10 gram balls melted down onto a tile to demonstrate fluidity, clarity and bubbling. Left is our standard cone 6 glaze. Right: G2813. It is flowing significant more, but not as much more as some others I am testing right now. Bottom: G3813 on a Polar Ice porcelain tile. It is high glossy, not crazing out of the kiln.
G3813 16x closeup of entrained bubbles
Others also had bubbles, but there are alot here. And they are all the same size (in clouds). Although the photo does not show it clearly, hundreds of these are breaking at the surface, leaving dimples. This was fired by drop-100F-an-soak. This would do better in clearing itself with thinner application.
G3814 Low Zinc High Feldspar Fritless base melt balls
Top: G3814 G2926B Plainsman whiteware base L3808A high B2O3 fluid clear G3813 Campana clear
Fluid cone 6 clear glazes
These are 10 gram glaze balls are fired down onto tiles to demonstrate melt fluidity and bubbling. Left: L3808 GB clear from Shaun Mollonga (most fluid). G3808A fritted recalculation of former (best surface). G3813 Campana clear (most transparent). G3806B Panama Blue base. All of these survived 260F:Icewater test without crazing on M370, M390 and M340. Campana Clear is the smoothest on M340, Panama is second best.
Campana clear on Plainsman M370,340,390
These were ice water tested at 260F and did not craze. Coverage is defect free on all three clays.
Fluid cone 6 clear glaze comparison
Top are 10 gram balls melted down onto a tile to demonstrate melt fluidity and bubble populations. Second row: Plainsman M370 whiteware Third row: Plainsman M340 buff stoneware Fourth row: Plainsman M390 red stoneware Left to right: G3814 - not melting as well G2938 - Water blue base G3808 - High Gerstley Borate base G3808A - 3808 using frits instead G3813 - Campana base G3806B - Panama base
Cone 6 High Fluid Melt Transparents
The chemistry of these glazes falls outside typical cone 6 boron, soda, calcia, magnesia chemistry. Why? To achieve higher melt fluidity for a more brilliant surface and for more reactive response with colorant and variegator additions. Classified by most active fluxes they are: G3814 - Moderate zinc, no boron G2938 - High-soda+lithia+strontium G3808 - High boron+soda (Gerstley Borate based) G3808A - 3808 chemistry sourced from frits G3813 - Boron+zinc+lithia G3806B - Soda+zinc+strontium+boron (mixed oxide effect)
Compare four clear bases for copper blue
Has extenal picture also
The flow testers at the back and the melt-down-balls in from of them have 1% copper carbonate. The glazed samples in the front row have 2% copper carbonate. L3806B, an improvement on the Panama Blue recipe, has the best color and the best compromize of flow and bubble clearing ability.
XML (to paste into Insight)
<?xml version="1.0"?> <recipes version="1.0" encoding="UTF-8"> <recipe name="Campana Cone 6 Transparent Glaze" keywords="3134, Spodumene, Zinc" id="75226" key="S55jc2CW" date="2018-03-19" codenum="G3813" email="email@example.com"> <recipelines> <recipeline material="Spodumene" amount="11.000"/> <recipeline material="Ferro Frit 3134" amount="21.000"/> <recipeline material="EP Kaolin" amount="20.000"/> <recipeline material="Silica" amount="20.000"/> <recipeline material="Wollastonite" amount="20.000"/> <recipeline material="Zinc Oxide" amount="8.000"/> </recipelines> </recipe> </recipes>
Panama Cone 6 Adjustment 2015
High fluid melt glaze for reactive effects and super gloss colors
This is work I did in 2015 (in 2019 a much bigger project developed this further).
Copper Blue G8306C using copper carbonate, oxide
Right is G3806C, an adjustment to drop the thermal expansion of B. It does this by trading some of the high-expansion KNaO for a mix of MgO, ZnO and SrO. These is an improvement but it still could craze over time on high-kaolin or low silica porcelains. One more change: The one on the right uses 2% Copper Oxide instead of 2% Copper Carbonate (left). Both also add 2.5% tin oxide. Strangely the color is only slight darker (the oxide is a more concentrated form of copper than the carbonate).
Plainsman P300, M370 with copper blue glaze cone 6
This is the G3906C base plus 2.5% tin oxide and 2% copper oxide. The green glaze does craze over time on these bodies, but the inside glaze is a liner than will not.
3806C vs. other cone 6 clear glazes on a dark stoneware
Each pair of mugs shows a numbered glaze vs. G3806C on the right. The body is a red burning cone 6 stoneware, Plainsman M390.
G2926B, 3806C vs. Amaco C11 Clear at cone 6
Bottom right is P300 with three coats of C11. Bottom left: 10 gram ball of C11. 2926 B is top left, 3806C is top right.
G3806C Copper Blue on Polar Ice
Polar Ice is the easiest of Plainsman middle fire porcelains to fit a glaze to, although this glaze crazes on most other porcelains, it should stay craze free on this.
G3806C on a dark burning cone 6 stoneware
Plainsman M390. There is still some clouding, but it is better than other transparents we have used.
1 - Midnight
Fire fast to 2100F (300-400F/hr), then 100F/hr to 2200F, then drop fast to 2000F and soak half hour, then cool at 100F/hr to 1400F.
XML (to paste into Insight)
<?xml version="1.0"?> <recipes version="1.0" encoding="UTF-8"> <recipe name="Panama Cone 6 Adjustment 2015" keywords="High fluid melt glaze for reactive effects and super gloss colors" id="75786" key="sx74Yjr9" date="2019-12-16" codenum="G3806C" email="firstname.lastname@example.org"> <recipelines> <recipeline material="Silica" amount="26.300"/> <recipeline material="Kaolin" amount="19.700"/> <recipeline material="Dolomite" amount="8.700"/> <recipeline material="Strontium Carbonate" amount="4.400"/> <recipeline material="Ferro Frit 3110" amount="31.100"/> <recipeline material="Ferro Frit 3134" amount="6.600"/> <recipeline material="Zinc Oxide" amount="3.300"/> </recipelines> </recipe> </recipes>
Panama c6 - Lower COE #1
Auto Unity Formula
The first adjustment to G3806C, the recipe I have used by some years. I have reduced KNaO and raised Li2O to compensate (Li2O is a powerful flux and has very low expansion). The method to accomplish this is novel.
G2806D (with copper carbonate) on M340 at cone 6
G2806D melt flow test
Left is G3806C with copper oxide 2%. Right is G3806D with copper carbonate 2%. The melt fluidity is identical.bith are bubbling so the C might’ve carbonate also.
G3806D with 2% Copper Car (left), 2% Copper Oxide (right)
G3806C and D - both using Copper Oxide at 2%
G3806D on M340, Polar Ice at cone 6
G3806D on M340, M390 at cone 6
This is the copper oxide version.
Clockwise: G3806C,D,E,F on M370
F is more fluid, thus highlights contours better. C has 2% copper, the others 3%.
XML (to paste into Insight)
<?xml version="1.0"?> <recipes version="1.0" encoding="UTF-8"> <recipe name="Panama c6 - Lower COE #1" id="157007" key="w14QBHjM" date="2019-07-20" codenum="G3806D" email="email@example.com"> <recipelines> <recipeline material="Silica" amount="26.300"/> <recipeline material="Wollastonite" amount="4.000"/> <recipeline material="Kaolin" amount="15.700"/> <recipeline material="Dolomite" amount="5.700"/> <recipeline material="Strontium Carbonate" amount="4.400"/> <recipeline material="Ferro Frit 3110" amount="29.100"/> <recipeline material="Ferro Frit 3249" amount="5.600"/> <recipeline material="Zinc Oxide" amount="3.300"/> <recipeline material="Spodumene" amount="6.000"/> <recipeline material="Copper Carbonate" amount="3.000" added="true"/> <recipeline material="Tin Oxide" amount="2.500" added="true"/> </recipelines> </recipe> </recipes>