Lili Krakowski on mon 14 jun 10
Question the other day about slip for bisque.
The "never fail" slip used on leatherhard or maybe greenware did not =3D
work on bisque. =3D20
Clay/slips/glazes that think together, shrink together....All along the =3D
line it matters to co-ordinate, harmonize shrinkage. =3D20
However. For one Rhodes writes that to increase shrinkage in a slip one =
adds more ball clay in relation to kaolin; and to decrease shrinkage on =3D
adds kaolin at the "expense" of ball clay.
For c.1-6 Rhodes gives:
ball clay 25
neph sy 15
for use on DAMP Clay.
For use on bisque clay he gives:
Ball Clay 15
Calcined Kaolin 20
Neph Sy 15
The calcining of the kaolin in the "for bisque" recipe lowers the =3D
shrinkage of the slip. Rhodes uses borax to give the engobes a harder =3D
surface. I never use talc in engobes as the magnesium can affect color.
From CM a Pyrophyllite slip worth trying on bisque:
Ferro Frit 3110 12
For dark slips I always use some RedArt clay...
The Rhodes book is "Clay and Glazes for the Potter" and the original =3D
Greenberg edition has no ISBN!
The pyrophyllite recipe, besides being in some CM issue, appears in my =3D
article, "Showing Your Slip" PMI Vol I, Number 1, Nov.1998
Be of good courage