Modification Date: 2016-04-06 23:42:34
Member of Group: base
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.
|Rate (F)||Temp (F)||Hold (Min)||Step|
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.
It is still used today because of the simplicity of the recipe and that fact that it works so well with chrome-tin pink glazes.
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.
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.
G1214M with 5% added Mason 6666 stain makes a stunning black for cone 6.
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 is GR6-H Ravenscrag oatmeal over G1214M black on porcelain at cone 6 oxidation to create an oil-spot effect. Both were dipped quickly. You can find more detail at ravenscrag.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).
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.
Out Bound Links
A cone 6 base clear glaze recipe developed by deriving a recipe from a formula taken as an average of limit formulas
2003-06-21 - More information is available in the articles section at the Digitalfire Reference Database.
This glaze was born as a demonstration of how to use chemistry to convert a glossy cone 6 glaze into a matte.
2003-06-10 - Please click the article link below for more information. This recipe is adjustable in that you can raise and lower the silica to increase and decr...
MgO is the secret weapon of craze control. If your application can tolerate it you can create a cone 6 base glaze of very low thermal expansion that is very resistant to crazing.
In Bound Links
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.
The process we used to improve the 20x5 base cone 6 glaze recipe
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.
A recipe sourcing high MgO (from Ferro Frit 3249) to produce a low expansion glass resistant to crazing on lower silica porcelains.
2003-12-18 - The original impetus to create this recipe was to reduce the thermal expansion of the G1214M and G1215W recipes to work better on porcelains (the othe...
The ratio of silicon dioxide to alumina oxide is often used as an indicator of glaze matteness. A glaze with high alumina thus has a low silica:alumina ratio. This ratio has some value because alumina stiffens the glaze melt (stiffer melts do not smooth out as well on cooling thus creating a fired s...
By Tony Hansen+