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G1216L - Transparent for Cone 6 Porcelains

Modified: 2017-07-19 22:24:03

Incorporates some MgO (at the expense of CaO, KNaO) to reduce the thermal expansion of G1214M 5x20 glaze.

Material Amount
Ferro Frit 3134*10.30
Ferro Frit 3124*22.70


This glaze adjusts G1214M 5x20 to reduce its thermal expansion (incorporating MgO). It goes in the same direction as G1215U but does not add as much MgO and sources it from Talc instead of Ferro Frit 3249. The MgO is added at the expense of CaO, KNaO. Boron has also been increased a little. The thermal expansion has gone from 7.0 to 6.5. The two frits here are tuned to supply enough Al2O3 to keep the kaolin low enough to prevent shrinkage cracks on drying.

This glaze survives and 300F oven:ice-water crazing test on Plainsman M370.

It works well as a white (with 10% zirconium silicate) and as a black (5% Mason 6666 black stain).
However some users find that this do fire as glassy as our standard G2926B recipe.


Recipes G1216M - Cone 6 Ultraclear Glaze for Porcelains
Substitute for low expansion cone 6 G1215U, this sources MgO from talc instead of a frit
Recipes G1215U - Low Expansion Glossy Clear Cone 6
A recipe sourcing high MgO (from Ferro Frit 3249) to produce a low expansion glass resistant to crazing on lower silica porcelains.
Recipes G2916F - Cone 6 Stoneware/Whiteware Glossy Base Glaze
Crystal clear industrial dinnerware glaze
Articles G1214M Cone 5-7 20x5 Glossy Base 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.
Articles 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 base glaze of very low thermal expansion that is very resistant to crazing.

XML to Paste Into Insight

<?xml version="1.0"?>
<recipes version="1.0" encoding="UTF-8">
<recipe name="Transparent for Cone 6 Porcelains" keywords="Incorporates some MgO (at the expense of CaO, KNaO) to reduce the thermal expansion of G1214M 5x20 glaze." id="117" date="2017-07-19" codenum="G1216L">
<recipeline material="Minspar" amount="8.200"/>
<recipeline material="Ferro Frit 3134" amount="10.300"/>
<recipeline material="Ferro Frit 3124" amount="22.700"/>
<recipeline material="Wollastonite" amount="14.400"/>
<recipeline material="EPK" amount="18.600"/>
<recipeline material="Talc" amount="4.100"/>
<recipeline material="Silica" amount="21.600"/>
<url url="" descrip=""/>

By Tony Hansen

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