Zero3 L Low Expansion Variant
|
Code # G2931L |
| Materials | Amt | Units | |
|---|---|---|---|
| Ferro Frit 3195 | 19.000 | KG | 19.10% |
| EPK | 10.000 | KG | 10.05% |
| Ferro Frit 3249 | 19.000 | KG | 19.10% |
| Fusion Frit F-524 | 49.000 | KG | 49.25% |
| Zinc Oxide | 2.500 | KG | 2.51% |
Total:99.50 (R)
Auto Unity Formula
|
Si:Al: 6.4:1 6.3 (Molar:6.0) 1.5 Cost 0.00 per kg |
Notes
*This is a low-expansion version of the Zero3 Clear glaze (code G2931K), originally developed from the Worthington Clear Gerstley Borate based recipe. While G2931K fits the vitreous Zero3 porcelain and non-vitreous bodies containing talc (like Plainsman L212, L215), it crazes on others (e.g. Plainsman TerraStone, BuffStone, L210). This version drops its expansion drastically, from 7.4 down to 6.3 (by adding ZnO, ZrO and increasing MgO and SiO2).
Since the thermal expansion of this is higher than the original Wothington Clear and the L version is lower, it is thus possible adjust thermal expansion of either recipe by adding some of the other (to deal with shivering or crazing on almost any low fire body).
Do not try to use this with too little water. Mix it to 1.43 specific gravity and add vinegar or Epsom salts to gel it so that it stops moving (after vigorous stirring) in 2 or 3 seconds. When mixed right it applies very well to low or high porosity bisque (in a very thin layer if needed), it does not drip or move.
The hold:slow-drop firing schedule, like 04DSDH, is critical to a defect-free surface.
Pictures
G2931L and K clear glazes (for non-talc, talc bodies)
These pieces have underglaze decoration with a covering clear glaze. But the glazes are different. The G2931L (left) has a lower thermal expansion (to prevent crazing on non-talc bodies like this). The G2931K glaze fits the terra cotta because the latter contains significant talc (to raise its expansion to fit commercial glazes better). If you switched these glazes the left mug would craze the glaze and the right would would shiver it off in flakes.
Three low fire bodies that need three clear glazes
Because of glaze fit. Left: Plainsman Buffstone, contains no talc, fires buff. Center: L212 (about 25% talc). Right: L213 (about 45% talc, fires whiter). Talc raises thermal expansion. The centre glaze is G2931K (Insight-live reports COE 7.4), it fits L215 (also Zero3 porcelain and stoneware). It crazes on Buffstone and shivers on L213 and L212. G2931L has lower expansion (to work on zero-talc porous bodies). G2931H is higher (for talc bodies like L213).
G2931L2 and L on L212 at cone 04
The L2 is a beautiful transparent (even though it is applied quite thickly). The L2 has no micro-bubbles while the L does. The L2 is thicker. Neither are crazing after two days out of the kiln. L2 is still OK after two years.
L on F100 after 1 year - no crazing, cone 03
Also very strong and difficult to break
G2931L on Buffstone - Crazing after one year
L212 with G2931L glaze
1 year old. So crazing starting on the bottom.
Typecodes
ST-Untitled typecode
Alternate Code Number:GS04-1
XML (to paste into Insight)
<?xml version="1.0"?> <recipes version="1.0" encoding="UTF-8"> <recipe name="Zero3 L Low Expansion Variant" id="116168" key="W4zPGQSQ" date="2020-12-02" typecodes="ST" codenum="G2931L" picturebasename=""> <recipelines> <recipeline material="Ferro Frit 3195" amount="19.000" tolerance="" unitabbr="KG"/> <recipeline material="EPK" amount="10.000" tolerance="" unitabbr="KG"/> <recipeline material="Ferro Frit 3249" amount="19.000" tolerance="" unitabbr="KG"/> <recipeline material="Fusion Frit F-524" amount="49.000" tolerance="" unitabbr="KG"/> <recipeline material="Zinc Oxide" amount="2.500" unitabbr="KG"/> </recipelines> </recipe> </recipes>
Born: 2006-03-16, Modified: 2020-12-02 07:29:04
Zero3 K Cone 03 Transparent Glaze
|
Code # G2931K |
| Materials | Amt | |
|---|---|---|
| Ferro Frit 3195 | 25.000 | 26.32% |
| Ferro Frit 3134 | 33.000 | 34.74% |
| EPK | 20.000 | 21.05% |
| Ferro Frit 3249 | 10.000 | 10.53% |
| Ferro Frit 3110 | 7.000 | 7.37% |
Total:95.00
Auto Unity Formula
|
Si:Al: 6.1:1 7.4 (Molar:7.5) 3.1 Cost 0.00 per kg |
Notes
*This recipe improved on the popular Worthington Gerstley-Borate-based low fire clear recipe. It targeted cone 03 to work best on Zero3 stoneware and porcelain. To fire lower (cone 06-04), consider G1916Q (or derivatives) instead.
Unlike its Worthington Clear predecessor, this does not become a bucket of jelly, does not crack on drying, does not go on unevenly or the wrong thickness, does not cloud up with boron blue or micro-bubbles when fired (because it has lower CaO) when used on the types of bodies discussed below. It is crystal clear and super glassy at cone 03.
If you liked the variegated appearance of the GB version, titanium dioxide can be added to this to produce even better variegation. For darker color rutile with do the same.
Low fire bodies span a wide range of thermal expansions. While Worthington clear (an ancestor of this recipe) melts to a good clear, its thermal expansion was too low. This recipe, G2931K, raises thermal expansion (by adding Na2O). The thermal expansion of Zero3 stoneware and porcelain are about the middle of the range, and they develop good glaze:glaze interfaces, so this recipe fits them well.
This glaze shivers on high-talc bodies and can craze on zero-talc porous ones. This recipe has three variations we have worked with, one of higher expansion (G2931H) and one of lower expansion (G2931L). Keep in mind that adding zircon and stains changes expansion.
Dipping ware in Zero3 Transparent is just so much easier than trying to paint on commercial, slow-drying clears. For us it naturally gels to a creamy consistency at around 1.53 specific gravity (in our circumstances). However it goes on too thick at that high a value, we have found the best all-around performance at 1.43 with enough Epsom Salts to gel it back up to a creamy thixotropic consistency (a few grams per gallon).
Pay special attention to the drop-and-hold firing schedule, especially if your clay body is not fine-grained. Use 04DSDH as a model.
To mix up 5 Kg use about 4.5 kg of water to get 6.5 litres of dipping glaze. To make a brushing glaze: For each 100g of powder mix start with 125 water, 1.5 CMC gum and 1.5 Veegum and thoroughly mix in a kitchen blender (add water if it gels too much). We find the about 330g of powder produces a 500ml (about 1 pint) jar.
To make colored versions add stains as needed (if stains cause micro-bubbling or orange peel surface include 2-3% zircopax).
Batch Ticket Notes
These notes were entered in the notes panel under "Batch Ticket Notes"
Pictures
G2931K on Zero3 Stoneware
Fired cone 03. Body is Zero3 stoneware.
Surface is perfect, even where thick. Ultra clear.
Survived three boil:ice cycles and one 300F:ice cycle without crazing.
G2931F vs. G2931K on Polar Ice Low Fire
2931F was the Ulexite flused version of this recipe. The F survived three boil:ice cycles and 1 300F:ice cycle without crazing or shivering.
The K is slightly smoother, tiny dimples in the surface are fewer. It is also applied thicker.
G2931F vs G2931K fritted - terra cotta mugs cone 03
F was the Ulexite-fluxed version of this recipe.
G2931F vs G2931K flow test
These two recipes have the same chemistry, but K sources boron from frits rather than Ulexite. Notice how much less bubbles there are in the flow and how much more predictable the melting pattern is.
G2931F vs G2931K - Melted balls at cone 03
F, the Ulexite version, is obviously bubbling more, the percolation is causing the melt to spread out more on the tile. On the flow test is was less fluid.
Firing temperature is important for Zero3 glaze
This is G2931F on Plainsman Buffstone, L213, F100, L215. First column is cone 04, center is cone 03, right is cone 02. All exited the kiln without crazing except Buffstone at cone 04.
We subjected all of them to a 300F:IceWater thermal shock.
Buffstone crazed on all of them.
L215 and L212 Cone 04 crazed.
L213 was good but later the glaze was found to be under excessive compression, subject to shivering over underglazes.
At cone 02 there are some dimples and defects.
Three low fire bodies that need three clear glazes
Because of glaze fit. Left: Plainsman Buffstone, contains no talc, fires buff. Center: L212 (about 25% talc). Right: L213 (about 45% talc, fires whiter). Talc raises thermal expansion. The centre glaze is G2931K (Insight-live reports COE 7.4), it fits L215 (also Zero3 porcelain and stoneware). It crazes on Buffstone and shivers on L213 and L212. G2931L has lower expansion (to work on zero-talc porous bodies). G2931H is higher (for talc bodies like L213).
G2931K glaze precipitates things on storage
G2931K On L212 after a year
Some crazing starting.
K on L215 at cone 04
The thicker version is clouding. The thinner one has micro-pinholes. It needs a higher temperature.
G2931K o L215 - Cone 03, thick application
G2931K on L215 - Cone 03 fired in 30 minutes
Very transparent. No crazingafter many months.
G2931K on L215 - Cone 06
Milky (because cone 06 is underfired for this glaze). But only a little crazing after a year.
G2931K running on Zero3 Casting
This happened at cone 03 and 04. The G3879 (left) did not run. For some reason G2931K easy applies to thickly on this body.
This 1000 gram batch of glaze powde
This 1000 gram batch of glaze powder screened 80 mesh immediately after making, and allowed to sit for 3 months prior to usage.
The material in photo was screened out once again after the 3 month time lapse, (80 mesh once again).
The largest balls are approx. 2.5 mm. in diameter, and when these particles were screened out, and still perhaps slightly wet?, they were quite easy to break in half with your fingernail.
G1916Q (left) vs G2931K (right) at cone 04
On a terra cotta body, the G1916Q is performing better, there are less micro bubbles.
URLs
How to tune the thixotropy of a glaze
How to convert a d..o a brushing glaze
Typecodes
ST-Untitled typecode
Alternate Code Number:GS04-1
XML (to paste into Insight)
<?xml version="1.0"?> <recipes version="1.0" encoding="UTF-8"> <recipe name="Zero3 K Cone 03 Transparent Glaze" id="95671" key="51HrvjPe" date="2023-05-03" typecodes="ST" codenum="G2931K" picturebasename=""> <recipelines> <recipeline material="Ferro Frit 3195" amount="25.000" tolerance=""/> <recipeline material="Ferro Frit 3134" amount="33.000" tolerance=""/> <recipeline material="EPK" amount="20.000" tolerance=""/> <recipeline material="Ferro Frit 3249" amount="10.000" tolerance=""/> <recipeline material="Ferro Frit 3110" amount="7.000" tolerance=""/> </recipelines> </recipe> </recipes>
Born: 2006-03-16, Modified: 2023-05-03 20:54:14
Zero3 H High Expansion Variant
|
Code # G2931H |
| Materials | Amt | Units |
|---|---|---|
| Ferro Frit 3195 | 30.000 | KG |
| Ferro Frit 3134 | 33.000 | KG |
| EPK | 20.000 | KG |
| Ferro Frit 3110 | 17.000 | KG |
Total:100.00 (R)
Auto Unity Formula
|
Si:Al: 6.9:1 8.0 (Molar:8.1) 3.0 Cost 0.00 per kg |
Notes
*This is a high-expansion version of the Zero3 Clear glaze (code G2931K), originally developed from the Worthington Clear Gerstley Borate based recipe. While G2931K fits the vitreous Zero3 porcelain and stoneware and also non-vitreous low-talc bodies (like Plainsman L212, L215), it shivers on high-talc bodies (e.g. Plainsman L213). That means that this G2931K variant is the most similar to commercial low fire glazes (which are designed to fit high-talc bodies).
This version increases the thermal expansion of Zero3 K glaze from 7.4 to 8.0 (by adding increasing KNaO at the expense of MgO, ZnO).
Do not try to use this with too little water. Mix it to 1.43 specific gravity and add vinegar or Epsom salts to gel it so that it stops moving (after vigorous stirring) in 2 or 3 seconds. When mixed right it applies very well to low or high porosity bisque (in a very thin layer if needed), it does not drip or move.
The hold:slow-drop firing schedule, like 04DSDH, is critical to a defect-free surface.
Pictures
Three low fire bodies that need three clear glazes
Because of glaze fit. Left: Plainsman Buffstone, contains no talc, fires buff. Center: L212 (about 25% talc). Right: L213 (about 45% talc, fires whiter). Talc raises thermal expansion. The centre glaze is G2931K (Insight-live reports COE 7.4), it fits L215 (also Zero3 porcelain and stoneware). It crazes on Buffstone and shivers on L213 and L212. G2931L has lower expansion (to work on zero-talc porous bodies). G2931H is higher (for talc bodies like L213).
L212. L2931K shivering. L2931H is good.
However the H did shiver off underglaze a little over time. On one piece. After a year it was notcrazed.
G2931H on L213 after one year - No crazing
Typecodes
ST-Untitled typecode
Alternate Code Number:GS04-1
XML (to paste into Insight)
<?xml version="1.0"?> <recipes version="1.0" encoding="UTF-8"> <recipe name="Zero3 H High Expansion Variant" id="116674" key="XT9Thj82" date="2020-12-02" typecodes="ST" codenum="G2931H" picturebasename=""> <recipelines> <recipeline material="Ferro Frit 3195" amount="30.000" tolerance="" unitabbr="KG"/> <recipeline material="Ferro Frit 3134" amount="33.000" tolerance="" unitabbr="KG"/> <recipeline material="EPK" amount="20.000" tolerance="" unitabbr="KG"/> <recipeline material="Ferro Frit 3110" amount="17.000" tolerance="" unitabbr="KG"/> </recipelines> </recipe> </recipes>
Born: 2006-03-16, Modified: 2020-12-02 07:28:17
Firing Schedule Name
Cone 03 hold-rise-drop-hold
Degrees (Fahrenheit or Celcius)
F
Schedule Type
Rate
Start Time and Temperature
8:01 am at 80F
Program
| Step | Degrees/Hr | Temperature Monitor |
Hold Time |
Accumulated hrs:min |
Time | Note |
|---|---|---|---|---|---|---|
| 1 | 400 | 240 | 60 | 1:24 | 9:25 am | |
| 2 | 350 | 1850 | 30 | 6:00 | 2:01 pm | |
| 3 | 108 | 1950 | 10 | 6:55 | 2:56 pm | |
| 4 | 500 | 1850 | 30 | 7:07 | 3:08 pm |
Notes
Used to glaze fire Zero3 porcelain and stoneware. However, there is a caution about bisquing these frit-containing bodies: They will vitrify in a typical firing, you must reduce the temperature to around 1500F (if ware is not absorbent enough fire lower). Note: this schedule is for the glaze firing, the previous two sentences simply referenced what is needed for the bisque.
This can start and finish more than once in a working day. Step 2 can often be done as fast as your kiln will go (cold-to-cold in three hours is possible).
The soak at 240F does not fracture ware even though it is above the boiling point of water. We find this is needed to be sure ware is sufficiently dry to withstand the rapid ascent to 1850. If your ware is thicker a slower ascent may be needed.
The 1850 soak on the way up clears the clouds of microbubbles. The 1850 soak on the way down heals the defects (blisters, pinholes) because the increasing viscosity is enough to overcome the surface tension holding bubbles from breaking).
It may be necessary to alter the last step if any imperfections are present. Try dropping to 1800 or 1750 and holding there. An additional step could be added to cool at 100F/hr down to 1500.
