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Plattypus

Sludge And Resist

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Hello fellow enthusiasts,

 

two questions: My Middle school students are using Amaco wax resist when glazing. The various glazes tend to only partially roll off after we dip or pour. Some times it is applied on an under-glazed design, in addition to the foot. In either case, we often need to wipe quite a bit of the glaze away with a sponge because the resist is not completely effective but when the design is delicate the kids often have trouble getting it off the design without marring the rest of the surface. Any ideas on how to remedy this? Should the under-glaze be rubbed with a finger? I seem to have a memory of doing that but don't know why.

 

My other question is about glaze consistency. Middle schoolers have great difficulty in brushing glaze effectively so I transfer all of my glazes to lidded buckets from which we dip and pour. A few of my glazes get such a thick residue on the bottom that even my electric drill can't cut through it. I end up removing the liquid, cutting through the sludge with a knife and then slowly blending the liquid back in. With one of them, Dry Champagne, I have to do that every couple of days or the kids can't use it. Any ideas why this is happening and is there anything I can do to stop it?

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Re: glaze settling problem from Vince Pitelka's "Clay, a studio handbook" ...

A fabulous reference book that should be on everyones shelf ...

 

Some glazes settle badly over time ... If you have this problem you might

want to consider adding a suspension agent such as 1/4 to 1% ( of dry batch weight)

Epsom salts or 2% Bentonite. Either or both of these will usually retard settling.

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Hi Chris, thanks for that suggestion. These are glazes I am buying in liquid form from Sheffield. Any thoughts on how to translate those percentages from dry weight to a liquid measurement?

 

Re: glaze settling problem from Vince Pitelka's "Clay, a studio handbook" ...

A fabulous reference book that should be on everyones shelf ...

 

Some glazes settle badly over time ... If you have this problem you might

want to consider adding a suspension agent such as 1/4 to 1% ( of dry batch weight)

Epsom salts or 2% Bentonite. Either or both of these will usually retard settling.

 

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Hi Chris, thanks for that suggestion. These are glazes I am buying in liquid form from Sheffield. Any thoughts on how to translate those percentages from dry weight to a liquid measurement?

 

 

 

You'll want to look up Broginarts formula. Then send me an email and I'll forward you my excel spreadsheet to do the math for you if you want.

You'll need a good graduated cylinder. I got a plastic 100ml cylinder form US plastics online. Cheap too. http://www.usplastic...35635&catid=529

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while the Sheffield wax resist is good for many thing I have come to love just plain old paraffin wax melted in an old electric skillet for dipping or brushing onto the underside of my wares before I glaze them. You can find that wax in most hobby shops back in the candle making stuff. The great thing about it is it is not only cheaper but it also makes clean up a breeze. The one fall back of it is that once it is on the pot it does not come off unless you re-bisque it. Hope this helps

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