Lance Hall
New Member
Lance Hall, married to Maureen, StillPoint Pottery
Posts: 17
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Post by Lance Hall on Nov 21, 2016 19:32:09 GMT -6
I have been using a basic slip with 20% red inclusion stain added, applied to leather hard ware. After bisque, some of the slip has not adheared to the pot and bubbled up. Im guessing that I should have calcined part of the clay in the slip. Looking forward to your comments.
Thanks, Lance
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Post by John Garrison on Nov 22, 2016 8:23:33 GMT -6
What type of slip are you using? Same as the clay body or a porcelain slip over a stoneware? How are you applying it? I find that 15% works best, for me but thats also dependant on how dark you want your color.
I spray ware after a few hours of turning with a HVLP spray gun, that way it drys at roughly the same rate and has a more even coating.
There are multiple ways of doing this as other members can contest to. Testing, Trial, and error until you find what works best for your work.
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BillC
New Member
Posts: 4
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Post by BillC on Nov 22, 2016 10:23:20 GMT -6
We had that problem, and used a trick that I learned from John Glick. About 1% borax will keep your slop where it belongs.
Bill
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annie
Junior Member
Posts: 55
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Post by annie on Nov 23, 2016 10:37:18 GMT -6
Hi Bill, What is it about adding 1% borax that keeps it in place? I've done test tiles thus far but plan to start using slips in earnest soon. I was planning on pouring my slip over the pieces, in lieu of spraying to start. One of my questions is how to compensate for shrinkage if I use a porcelain slip with stain over my porcelain/stoneware blend body. Any advice?
--Annie
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Post by lonaugh on Nov 24, 2016 11:33:23 GMT -6
I am using Harry Fraser porcelain slip straight onto an iron bearing stoneware body, I brush it on or dip pieces when I can.I have had good results so far but last firing I had bloats and parts where the porcelain slip was coming away from the clay body...I too would love to know what the addition of Borax 1% would do to help this..I also read somewhere that it may be due to too low a temperature on the bisque firing.......anyone have any ideas about this?
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Lance Hall
New Member
Lance Hall, married to Maureen, StillPoint Pottery
Posts: 17
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Post by Lance Hall on Dec 6, 2016 9:50:11 GMT -6
Hi all,
When I posted my question I had engaged my fingers before my brain. The issue is all about shrinkage. Make a pot, wait till it dries enough to trim and of course it has begun to shrink. Put on a slip that is designed for damp clay and naturally it will crawl. If I had been thinking a bit the slip needs to have a portion or all of the kaolin calcined. no problems after that.
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Post by wmcampbell on Dec 6, 2016 13:38:00 GMT -6
What John Glick had to say about using borax was, that the shape of the borax crystal was what held the slip in place. I use it routinely in my slip and it always works. It is applied to bone dry pots that have not been bisqued. The slip is the same clay that is in the body of the pot.
Borax can be found in your local grocery store.
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joerg
New Member
website: www.crystalsforever.com
Posts: 49
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Post by joerg on Dec 6, 2016 14:59:58 GMT -6
a.) moisten the leatherhard piece with a humid rug before applying the slip
b.) don't apply slip too thick , better thin, slightly drying with a gas or electric burner until slip gets matt and apply again
c.) still humid , but matt, I smoothen (compress...) the slip with a smooth/ polished hematite stone...
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annie
Junior Member
Posts: 55
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Post by annie on Dec 7, 2016 11:35:10 GMT -6
Thanks Bill and Joerg. Looks like Borax will be added to my shopping list when next in the States.
--Annie
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Post by wmcampbell on Dec 7, 2016 12:51:26 GMT -6
Borax is in every grocery store, and it is cheap.
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annie
Junior Member
Posts: 55
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Post by annie on Dec 13, 2016 2:21:24 GMT -6
Found real Borax on-line in UK (vs the substitute sold in most stores). Awaiting delivery--and yes it is cheap!
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