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Cone 6 Whiteware/Porcelain Transparent Base Glaze

Code: G2926B
Modification Date: 2019-03-27 13:20:33

A base transparent glaze recipe created by Tony Hansen for Plainsman Clays, it fires high gloss and ultra clear with low melt mobility.

MaterialAmountPercent
Nepheline Syenite18.316.6%
Ferro Frit 313425.423.1%
EPK19.617.8%
Wollastonite6.96.3%
Silica37.634.2%
Talc2.32.1%
 110.10  

Firing Schedule

Rate ()Temp ()Hold (Min)Step
108250601
350209502
1082195103
9992095304

Notes

A cone 6 transparent general purpose base recipe developed at Plainsman Clays by Tony Hansen (see link to go there below, it contains technical and mixing information about the recipe).

This is an adjustment to an original recipe named Perkins Studio Clear (it contains alot more SiO2 and uses a frit instead of Gerstley Borate as the boron source). It is just as shiny and transparent, has a less fluid melt and will be harder and for stable. With this change this is a really stunning transparent glaze. We have found that it will even tolerate 5% more silica than what is shown here, yet still smooths out well. The reason why that is so good is that higher silica contents produce a more durable glass.

In our testing this glaze survives a 300F oven-to-icewater test without crazing on Plainsman M370 (25-Porcelain using Nepheline, Tile#6 Kaolin, silica and Old Hickory ball clay. It is less affected than the original when the application is too thick (minimal bubbles and crazing).

If you just want to mix it the traditional way, then start with 90 water to 100 powder (by weight) and agitate well using a propeller mixer. Then add more water until it is creamy, try it, adjust, etc. However this recipe has the best suspension and application properties when it is thixotropic (that involves mixing it thinner than normal and gelling it using Epsom salts). Target a specific gravity of 1.43-1.44 (equal weights of water and powder should be slightly above this). Then about add 1g of Epsom salts per 1000g powder to increase thixotropy. This should make it creamy and it should gel after a few seconds on standing still (add more Epsom salts if needed, but be careful, it is easy to over-do it).

Since the slurry is not too far from 50:50 water:powder, you could add colors and opacifiers on that basis. For example, 1000g of slurry has about 500g of powder. For white you need 10% zircopax, so that is 50g. This is approximate, but suitable for testing. Later if you decide a mix has promise then mix-from-scratch with the right percentages.

Screen through 80 mesh (tiny wollastonite agglomerates are possible, they will not break down without screening).

Plainsmanclays.com makes this recipe as a premixed powder. The glazes section on their site has additional info.

If this crazes see the links below. This glaze melts early, it is not suitable for decals which need refining to cone 022.

Out Bound Links

In Bound Links

XML to Paste Into Insight

<?xml version="1.0"?>
<recipes version="1.0" encoding="UTF-8">
<recipe name="Cone 6 Whiteware/Porcelain Transparent Base Glaze" keywords="A base transparent glaze recipe created by Tony Hansen for Plainsman Clays, it fires high gloss and ultra clear with low melt mobility." id="118" date="2019-03-27" codenum="G2926B">
<recipelines>
<recipeline material="Nepheline Syenite" amount="18.300" unitabbr="kg" conversion="1.0000" added="0"/>
<recipeline material="Ferro Frit 3134" amount="25.400" unitabbr="kg" conversion="1.0000" added="0"/>
<recipeline material="EPK" amount="19.600" unitabbr="kg" conversion="1.0000" added="0"/>
<recipeline material="Wollastonite" amount="6.900" unitabbr="kg" conversion="1.0000" added="0"/>
<recipeline material="Silica" amount="37.600" unitabbr="kg" conversion="1.0000" added="0"/>
<recipeline material="Talc" amount="2.300" unitabbr="kg" conversion="1.0000" added="0"/>
<url url="https://digitalfire.com/4sight/recipes/cone_6_whitewareporcelain_transparent_base_glaze_118.html" descrip="Recipe page at digitalfire.com"/>
</recipelines>
<urls/>
</recipe>
</recipes>


By Tony Hansen




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