[Goliath]

I belong to a studiio that currently uses a Sky Blue glaze that contains Bentonite.


Within 5 days, the glaze has become to thick to stir. When this happens to our other glazes, we add Epsom Salts.


Does anyone know if that can be done when Bentonite is an ingredient in the glaze?


WOuld adding more Bentonite help??


Please help!!! Need to fix this glaze asap.



Thanks

[bciskepottery]

Try these:

http://www.youtube.c...h?v=fpQns05RdVU

http://ceramicartsda...etter-coverage/

[neilestrick]

By 'too thick to stir' do you mean it has settled out in the bottom of the bucket? Epsom salts is a flocculant- it makes particles stick together. Bentonite and epsom salts are a great combination to keep a glaze in suspension. The bentonite (and other clay) suspends very well, and the epsom salts make everything else stick to it so they doesn't settle out hard in the bottom of the bucket. Use about 2% bentonite and 1/2% epsom salts by dry weight. The bentonite should be mixed well with other other ingredients before adding water to keep it from clumping.

[TJR]

GOLIATH;
I USE BENTONITE EXCLUSIVELY IN ALL MY GLAZES TO PREVENT SETTLING. I NORMALLY USE 3% ADDED TO THE DRY MIX BEFORE ADDING WATER.Sorry, caps on again. Epsom salt changes the electrical charge at the molecular level. The reason a lot of people use it, is because it can be added to the wet glaze in the bucket. Look at your recipe. If you have a lot of flint or fritt in a glaze, it will settle out. Post the glaze if you can and we will see what the problem is.
TJR.

[Ben]

Goliath, on 19 March 2013 - 09:46 PM, said:

I belong to a studiio that currently uses a Sky Blue glaze that contains Bentonite.


Within 5 days, the glaze has become to thick to stir. When this happens to our other glazes, we add Epsom Salts.


Does anyone know if that can be done when Bentonite is an ingredient in the glaze?


WOuld adding more Bentonite help??


Please help!!! Need to fix this glaze asap.



Thanks

Can you post the glaze recipe?
Some ingredients dissolve into the water and cause it to deflocculate and settle out or "hardpan" though this can also be caused by not having enough clay particles to keep the glaze in suspension. All glazes will settle you just don't want them to be so hard in the bottom of the bucket that you can't stir them up easily. Epsom salt can counteract this effect IF and only IF there is enough clay in the glaze for the epsom salt to work on. Epsom salt helps flocculate the clay particles so that they clump together in suspension. Now, if MORE defflocclant dissolves out of the glaze after you add epsom salts it can settle out again.

In this case you can wash the soluble ingredient out by letting it settle and pouring off the water and replacing it with fresh. After a few times you will have discarded the soluble ingredient but beware, you are also throwing out a glaze ingredient and the glaze may well change how it fires.

If the glaze has very little clay in it the epsom salt may not be enough to keep it suspended.

Best,
Ben

[Pres]

neilestrick, on 20 March 2013 - 09:12 AM, said:

By 'too thick to stir' do you mean it has settled out in the bottom of the bucket? Epsom salts is a flocculant- it makes particles stick together. Bentonite and epsom salts are a great combination to keep a glaze in suspension. The bentonite (and other clay) suspends very well, and the epsom salts make everything else stick to it so they doesn't settle out hard in the bottom of the bucket. Use about 2% bentonite and 1/2% epsom salts by dry weight. The bentonite should be mixed well with other other ingredients before adding water to keep it from clumping.

I usually keep a gallon container of water saturated with Epson salts in the studio. This allows me to add a tablespoon at a time to my glazes. I have found it especially helps with glazes low in clay content to add both the Epsom salts and the bentonite.