Lapidaryforum.net
Rockin' Jewelry => Tutorials for Jewelry Making => Topic started by: lithicbeads on May 19, 2017, 10:15:48 AM
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This formula for Egyptian paste comes from the recently deceased Robin Hopper the famous Canadian potter , gardener and educator. He received the Order of Canada shortly before he died a gigantic tribute from his adopted country. Feldspar 40 % , silica 20 % , kaolin 15 % , ball clay 5 % , sodium bicarbonate 6 % , soda ash 6 % , calcium carbonate 5 % , fine white sand 8 % ,bentonite 5 % .This is not a clay it is packed into a mold or crudely modeled. It is porous so that the oxides can migrate to the surface during drying and firing to provide color. Copper oxide or copper carbonate at about 3 % will give the strong turquoise color that is traditional. Other oxides and mason stains may also be used. It is fired at cone 012 to 04 with the standard being cone 08.
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Very interesting. I always wondered how it was made.
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Here is another similar formula from " Ceramics " fourth edition written by Glen C. Nelson.cone 08 self glazing body. 40% Buckingham spar ( feldspar) , 20 % flint ( silica) , 15 kaolin , 6 % bicarbonate of soda , 6 % soda ash . 5 % ball clay , 5 % dolomite , 3 % bentonite. Colorants : purple - blue 3/4 % cobalt ;light green 1 % copper carbonate ; yellow 7 % vanadium stain. The composition of Buckingham spar is sio2 65.5 % , al2o3 19.5 % , cao .16 % , mgo .2 % , k2o 12.4 % , na2o 2.6 %.
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I missed seeing this last week. Thank you for posting these formulas. Duly copied and saved. I checked my local ceramics store and it seems that they have almost all of these components. Everything looks fairly inexpensive except for the stains.
This is one of those things I've always wanted to try someday. Thank you so much!
Debbie K
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Thanks for posting this Frank! Very useful. Now that I have a kiln that goes up to 2000F I can do low fire pieces so long as they don't get to big in size as my firing chamber is only 7x6x6.
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That should be plenty large to have lots of fun .