|Monthly Tech-Tip |
Modified: 2019-07-05 20:13:04
A recipe developed by Tony Hansen in the 1980s. Its was popular because of the simplicity of the recipe and how well it worked with chrome-tin stains.
|Ferro Frit 3134||20.00|
This is also known as the 20x5 recipe. It was developed during the early 1980s to demonstrate principles of glaze chemistry in creating a glaze base sympathetic to the development of chrome-tin pinks and maroons. Articles a videos about this were used a selling tools for Digitalfire Insight software.
This recipe was developed over the years and had many versions. We now recommend G2926B as a base instead.
This demonstrates how the host glaze affects the color development of certain stains. Blue is stable in pretty well all glazes. But chrome tin pink (top row) is very particular that the glaze have the right chemistry (1214M is obviously best, it has the highest CaO and lowest B2O3). The 6100 brown works much better in the N and O base glazes (they have higher Al2O3). Stain companies have guidance on chemistry particulars and you can view the chemistry of your recipe in your account at insight-live.com.
The underglaze is G1214M cone 6 black (adds 5% Mason 6666 black stain). Overglaze left: GR6-H Ravenscrag Oatmeal. Overglaze right: GA6-F Alberta Slip oatmeal. Both produce a very pleasant silky matte texture (the right being the best). Both layers are fairly thin. In production it would be best to spray the second layer, keeping it as thin as possible. It is also necessary to adjust the ratio of raw to calcined Alberta or Ravenscrag Slips to establish a balance between drying hardness but not too much drying shrinkage (and resultant cracking).
The black recipe was made using G1214M with 5% Mason 6666 stain. The oatmeal overlayer is 50% the thickness of the black. The more fluid under-black comes through leaving islands and vertical rivulets of the stiffer oatmeal. Good control of the glazing process is needed to get consistent results using this approach.
This shows clearly how well the M version works with a chrome-tin stain compared to the others. However the 6100 brown stain works best in the N recipe (which have MgO). Notice also that the M has a higher thermal expansion than the others.
The cone 6 G1214M glaze on the left melts well. Can it benefit from a silica addition? Yes. The right adds 20% yet still melts as well, covers better, is more glossy, more resistant to leaching, harder and has a lower thermal expansion.
G1214M Cone 5-7 20x5 glossy transparent glaze
This is a base transparent glaze recipe developed for cone 6. It is known as the 20x5 or 20 by 5 recipe. It is a simple 5 material at 20% each mix and it makes a good home base from which to rationalize adjustments.
Bringing Out the Big Guns in Craze Control: MgO (G1215U)
MgO is the secret weapon of craze control. If your application can tolerate it you can create a cone 6 glaze of very low thermal expansion that is very resistant to crazing.
G1214Z Cone 6 matte glaze
This glaze was developed using the 1214W glossy as a starting point. This article overviews the types of matte glazes and rationalizes the method used to make this one.
G1214W Cone 6 transparent glaze
The process we used to improve the 20x5 base cone 6 glaze recipe
A formula ratio used to evaluate and predict firing properties in ceramic glazes.
Transparent Glaze Recipe
Transparent recipes can be difficult to develop because entrained bubbles, crystals and crazing are not hidden by color and opacity. In addition, they must be well melted to give good results. Generally transparent recipes are sought after as liner glazes or bases to which to add opacifiers and colors. Typically work is required to match a transparent glaze to a specific clay body.
INSIGHT Glaze Recipes
These are sample recipes included with INSIGHT software.
Medium Temperature Glaze Recipes
Normally fired at cone 5-7 in electric kilns.
G1214W - Cone 6 Transparent Base
A cone 6 base clear glaze recipe developed by deriving a recipe from a formula taken as an average of limit formulas
G1214Z1 - Cone 6 Silky Matte
This glaze was born as a demonstration of how to use chemistry to convert a glossy cone 6 glaze into a matte.
G2926B - Cone 6 Whiteware/Porcelain transparent glaze
A base transparent glaze recipe created by Tony Hansen for Plainsman Clays, it fires high gloss and ultra clear with low melt mobility.
Plainsman Cone 6 Electric Standard
Used in the Plainsman lab to fire clay test bars in our small kilns
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|By Tony Hansen|
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