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White Engobe for M390, M340

Code: L3954B
Modification Date: 2018-07-04 22:55:36

Nepheline Syenite18.0
Ball Clay54.0


This recipe has been tuned to have about the same drying and fired shrinkage as the target clay bodies Plainsman M390 and M340 (this has more Zircopax and less flux than previous trials). Fired shrinkage was matched using the EBCT test.

Ball Clay: We use Old Hickory M23, but you can substitute others (e.g. OM#4, Gleason).

The color is whiter than previous trials (because of the zircopax), but some might prefer a little blue stain to brighten the color. We used 0.2% Mason 6336 with good success, others we tried agglomerated and caused specking).

This is an engobe, it must be applied at stiff leather-hard stage (if you apply it to dry or bisque it will flake off). It will rewet pieces and they will require significant time to re-stiffen to the same state. Even coverage can normally only be achieved by preparing a slurry of the correct rheological properties and dipping or pouring. It is vital that you have a good mixer and can effectively measure specific gravity. To mix this use the process described on the “Engobe” glossary page at the Digitalfire Reference Library.

Examples of mixes we have done:
Add the Darvan to the water then add the clay, mixing while doing so.
5000g powder to 3900ml water to 20g Darvan produced less than two gallons having a specific gravity of 1.55 (proportions are thus 100:78:0.4). But after a day it was too fluid and a tiny amount of epsom salts was added to bring it back to a creamy texture. In future mixes we will start with 15 Darvan.

Brush-on version: 75g Laguna gum solution, 400g water, 500g powder (makes 1 pint). A good mixer is needed to mix in the last of the powder (or an overnight sit will break up the lumps). This produces brush-stroke coverage, which can be very attractive.

A black version, L3954F, can be made by substituting the Zircopax for Mason 6600 stain (7.5-15%). This produces a very high quality black color.

Out Bound Links

XML to Paste Into Insight

<?xml version="1.0"?>
<recipes version="1.0" encoding="UTF-8">
<recipe name="White Cone 6 Engobe for Plainsman M390, M340" id="134" date="2019-04-18" codenum="L3954B">
<recipeline material="Nepheline Syenite" amount="18.000" added="0"/>
<recipeline material="Silica" amount="15.000" added="0"/>
<recipeline material="Ball Clay" amount="54.000" added="0"/>
<recipeline material="Bentonite" amount="3.000" added="0"/>
<recipeline material="Zircopax" amount="10.000" added="0"/>
<url url="" descrip="Recipe page at"/>

By Tony Hansen

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