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Monday, November 05, 2012

Need help on thickness of slip for dipping and pouring

This morning I've been reading more of the Mary Wondrausch book "Slipware" and making some notes. There are some good hints in there as well as a wealth of information on classic, antique, slipware. I also ordered another book that she recommended - found a used library edition on Amazon for something like a dollar and a half.

Yesterday I made a batch of Ayumi's white slip, after a bad start botching the weighing on the first batch and spending way too much time trying to remove excess material. It was all a lost cause and I finally just grabbed a new bucket and started over. I think I made it too thin for pouring, so I could get it to go through a 100 mesh screen, so I will have to do some trial and error to test the correct thickness. After much searching in available books, you tube videos and googling articles, I haven't been able to find out what the specific gravity should be for pouring or dipping this slip. All I could find was the specific gravity for casting slip. If anyone knows how thick these slips should be for dipping or pouring, I would certainly appreciate your input!  Otherwise it's going to be trial and error.

On my "to do" list today is to make up a couple of black slip tests - one with a mix of oxides and another with black stain. I also want to just slab a few test tiles. As soon as it warms outside, I need to uncover the small soda test kiln and check those burners. I drilled them out so they would work with natural gas. If all looks good, I'll load it and fire tomorrow - a day later than I thought; but the weather still looks good for a firing tomorrow. They're forecasting the first freeze later in the week, so I need to get this done if at all possible.

Repair man just finished adjusting my range top burners, so it's time to grab my notebook and "to do" list and head for the studio.

4 comments:

  1. I dip and brush slip on leather hard work. I don't get so scientific as to measure specific gravity but where glaze generally looks like single cream, my slips are closer to double cream. (UK terms - I can't remember if we use the same terms for cream!) What I observe though is that how thick you want the slip depends very much on the state of the clay. My Terra sigilata is generally pretty thin and applied to nearly dry pots by brushing. The slips I apply by brush to leather hard pots on the wheel need to be a bit thinner than double cream otherwise they don't flow off the brush. The slip that I apply to leather hard pots by dipping wants to be a bit thicker otherwise there is just too much water going into the clay and the piece is more likely to flop. So in the end it does come down to trial and error I'm afraid.

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  2. Thank you Mike. I imagine that what you call single cream is what we call light cream and what you call double cream is what we call heavy or whipping cream.
    As it say, it looks like it will have to be trial and error.

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  3. Kevin Carter11/7/12, 5:27 PM

    Double cream is even thicker than heavy or whipping cream, almost 1.5 times as thick.
    Make it about the consistency of whole milk or 2% and it should work.

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  4. Thanks Kevin. I've been watching some youtube slipware videos today trying to get an idea of the thickness. I'm just going to have to play with this a while!

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