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High Bridge Pottery

A Few Glaze Problems, Drying To Slow... Not Enough Suspension.

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neilestrick    1,381

If a glaze is taking along time to dry, it's holding a lot of water. Glazes that are high in clay content often have this problem, so do those high in feldspar sometimes. A deflocculant such as Darvan or Sodium Silicate will allow you to make the glaze fluid enough to apply without using as much water. This is why we deflocculate casting slips. It makes the slip fluid enough to pour in and out of the molds, but with a low water content so that it dries faster and shrinks less.

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I ended up leaving the white glaze that took forever to dry because I liked it too much. Next batch I will probably try adding some sodium silicate to thin it out. Just figured out a way to get good coverage and no finger prints.

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Babs    386

What makes you think that the glaze is the correct "thickness' before you apply it to your pot? :rolleyes:

Perhaps it needs to have more water in it to start with. And slaked over night prior to usingand testing.

Test at varying Specific gravities  THEN,,

adjust with the flocculant/deflocculant depending whether it is a high clayglaze or other if still required..

High Bridge you asked whether the glaze formula mattered if it added up to 100 or not. If the guts of the glaze ie without the colourants and the bentonite (if added as an additive),  does not add up to 100 then you cannot just assume it can be used as written without first converting the amounts to a percentage of the total.

Soda Feldspar 51                    34.96%      (51/145.9x100)

Potash Feldspar 36.7

Quartz 25.5

Dolomite White 2

Whiting 18.9

China clay 2.6

Ball Clay 9.2

Total          145.9                     100

 

Iron Oxide 11  Would remain at 11 as this is an additive and for a iron rich glaze about normal .

And so on! :) DO the maths!!!

 

Apologies if some one has already answered This part, but didn't read that.

 

SO in this instance  Soda Feldspar  for this recipe would be   34.96

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