Project Name
Compare Cone 6 clear fluid glazes
Project Codenumber
UnAssigned
Notes
This project compares a variety of fluid-melt (runny) cone 6 base base glazes. Why do this? The initial objective was to create a good copper blue. But that was extended to create a fluid-melt base to which other oxide and stains can be added to make brilliant colors. Objectives:
-Learn the tradeoffs between these and a more stable melt bases (like G2926B).
-Find one that does not craze on common bodies.
-Compare their tendency to trap bubbles (in various types of bodies), the smoothness of their surfaces.
-Compare their reactions to various colorants, opacifiers.
-Compare their melt flows.
-Compare their behavior as slurries
These are the initial glazes. Some lived as colored glazes, but I removed the colorant to just look at the base clear. I had to adjust two of them immediately, they would not suspend in the bucket.
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
I chose an initial winner: G3806B (it is a second-step adjustment to the original to increase the clay content, while holding chemistry the same, to give it better working properties). I may revisit other bases (I like the Campana and 3808A also).
This project underscores the fact that textbook recipes (which the initial ones all were) need to be tested and adjusted to bring into our circumstances. Invariably they have one or more of the following problems: they settle, dry-crack, dust, gel, craze, shiver, blister, pinhole, leach or do not fire to a smooth surface. But in comparing the chemistry, materials and firing of a number of different ones one can pick the best and adjust that to get the final mix.
Panama Blue 3 - Copper Carbonate
3110, 3134, zinc, Sr
|
Code # G3806B |
| Materials | Amt |
|---|---|
| Custer Feldspar | 11.500 |
| Silica | 20.000 |
| Whiting | 1.000 |
| Kaolin | 15.000 |
| Dolomite | 8.000 |
| Strontium Carbonate | 4.000 |
| Ferro Frit 3110 | 29.500 |
| Ferro Frit 3134 | 7.500 |
| Zinc Oxide | 2.500 |
| Additions | |
|---|---|
| Tin Oxide | 2.500 |
| Copper Carbonate | 2.000 |
Total:103.50
Auto Unity Formula
|
Si:Al: 10.8:1 7.5 (Molar:7.3) 8.1 Cost 0.01 per kg |
Notes
*After a year of storage we found a considerable amount of hard dark precipitate lumps stuck to the bottom and walls of glaze bucket. Very hard and had to scrape off with fettling knife. This could be because of solubility of Frit 3110.
Pictures
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.
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.
2% Copper carbonate in two different cone 6 copper-blues
The top base glaze has just enough melt fluidity to produce a brilliant transparent (without colorant additions). However it does not have enough fluidity to pass the bubbles and heal over from the decomposition of this added copper carbonate! Why is the lower glaze passing the bubbles? How can it melt better yet have 65% less boron? How can it not be crazing when the COE calculates to 7.7 (vs. 6.4)? First, it has 40% less Al2O3 and SiO2 (which normally stiffen the melt). Second, it has higher flux content that is more diversified (it adds two new ones: SrO, ZnO). That zinc is a key to why it is melting so well and why it starts melting later (enabling unimpeded gas escape until then). It also benefits from the mixed-oxide-effect, the diversity itself improves the melt. And the crazing? The ZnO obviously pushes the COE down disproportionately to its percentage (although there is further to go because it is crazing somewhat).
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).
XML (to paste into Insight)
<?xml version="1.0"?> <recipes version="1.0" encoding="UTF-8"> <recipe name="Panama Blue 3 - Copper Carbonate" keywords="3110, 3134, zinc, Sr" id="75240" key="GCw3t1Nf" date="2017-01-07" codenum="G3806B" email="untdkm@sasktel.net"> <recipelines> <recipeline material="Custer Feldspar" amount="11.500" tolerance=""/> <recipeline material="Silica" amount="20.000" tolerance=""/> <recipeline material="Whiting" amount="1.000" tolerance=""/> <recipeline material="Kaolin" amount="15.000" tolerance=""/> <recipeline material="Dolomite" amount="8.000" tolerance=""/> <recipeline material="Strontium Carbonate" amount="4.000" tolerance=""/> <recipeline material="Ferro Frit 3110" amount="29.500" tolerance=""/> <recipeline material="Ferro Frit 3134" amount="7.500" tolerance=""/> <recipeline material="Zinc Oxide" amount="2.500" tolerance=""/> <recipeline material="Tin Oxide" amount="2.500" added="true"/> <recipeline material="Copper Carbonate" amount="2.000" added="true"/> </recipelines> </recipe> </recipes>
Born: 2015-06-02, Modified: 2017-01-07 12:21:33
Panama Cone 6 Adjustment 2015
High fluid melt glaze for reactive effects and super gloss colors
|
Code # G3806C |
| P | Materials | Amt | |
|---|---|---|---|
| Silica | 26.300 | 26.27% | |
| Kaolin | 19.700 | 19.68% | |
| Dolomite | 8.700 | 8.69% | |
| Strontium Carbonate | 4.400 | 4.40% | |
| Ferro Frit 3110 | 31.100 | 31.07% | |
| Ferro Frit 3134 | 6.600 | 6.59% | |
| Zinc Oxide | 3.300 | 3.30% |
| P | Additions | ||
|---|---|---|---|
| * | Copper Oxide | 2.000 | 2.00% |
| * | Tin Oxide | 2.500 | 2.50% |
Total:104.60
Auto Unity Formula
|
Si:Al: 11.1:1 7.3 (Molar:7.1) 7.9 |
Notes
*This is work I did in 2015 (in 2019 a much bigger project developed this further).
The copper and tin produce the turquoise celadon effect.
This recipe is for a brilliant fluid-melt transparent base glaze, initially for copper blues and greens, but later for stains. "Fluid-melt" means it runs down off ware if applied too thickly, this is a key for achieving many visual effects.
Initiailly I compared a number of recipes I found on line and finally selected Panama Blue. I removed the colorants and made adjustments to improve slurry properties and lower the thermal expansion (it has serious crazing issues). Fluid-melts have a down side: Crazing is an issue (because the fluid melt requires more fluxes, these have higher thermal expansions).
Then I did three adjustments, each lowering the thermal expansion more than the last. While keeping the same brilliant visual appearance. The recipe ended up being quite different (two materials were eliminated from the recipe, their oxides supplied by the others). The chemistry of this one moves much of the KNaO to low-expansion MgO. This makes it melt a little less, but visually it is the same. Higher ZnO helps melting (since MgO is not nearly as powerful a flux as KNaO). I was even able to add extra SiO2. The calculated thermal expansion has gone from 7.7 down to 7.3.
This worked well on stonewares but still crazed on Plainsman P300 and M370 (but was OK on Polar Ice). Fluid melt glazes look best on porcelains so this was obviously a problem. So I continued development in pursuit of a fluid melt having a lower thermal expansion (see subsequent articles, recipes and posts).
Pictures
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.
G3806D melt flow test
Left is G3806C with copper oxide 2%. Right is G3806D with copper carbonate 2%. The melt fluidity is identical. The blue color thus seems to depend on the carbonate (or a lower percentage of the oxide is needed).
Variations
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="ojnLoiHk" date="2024-01-18" codenum="G3806C" email="untdkm@sasktel.net"> <recipelines> <recipeline material="Silica" amount="26.300" tolerance=""/> <recipeline material="Kaolin" amount="19.700" tolerance=""/> <recipeline material="Dolomite" amount="8.700" tolerance=""/> <recipeline material="Strontium Carbonate" amount="4.400" tolerance=""/> <recipeline material="Ferro Frit 3110" amount="31.100" tolerance=""/> <recipeline material="Ferro Frit 3134" amount="6.600" tolerance=""/> <recipeline material="Zinc Oxide" amount="3.300" tolerance=""/> <recipeline material="Copper Oxide" amount="2.000" added="true"/> <recipeline material="Tin Oxide" amount="2.500" added="true"/> </recipelines> </recipe> </recipes>
Born: 2015-06-02, Modified: 2024-01-18 19:47:16
