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flocculants and deflocculants

updated fri 31 may 96

 

David Hewitt on sat 18 may 96

Hi Peter,
Am I right in thinking that you added the bentonite to the already mixed
glaze? If so I think this is the reason that it did not make any
difference to your glaze suspension. Bentonite should always be added to
the dry mix and dispersed in the dry mix by stirring as best as possible
before adding the water.
Calcium chloride is, as you know, a flocculant and obviously it has been
most effective in your glaze. You don't have to use it with bentonite
although it is not uncommon. It may well be used if you want to make
your glaze more creamy and easier to work with and, because this makes
it settle out too quickly, to include bentonite.
I do not, of course, know your basic glaze recipe, but would I be
correct in guessing that it is low in clay and includes a frit? Some
re formulation could perhaps be another solution. May I suggest,
however,
that you start again with a 1Kg, or similar small amount of mix, and add
2% Bentonite and see how this suspends.
David Hewitt
David Hewitt Pottery Caerleon, Newport, Gwent, UK.