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1. Thinning Glazes. 2. Deliberate Creating Of Pinholes


MichaelP

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1. When I use Coyote glazes in a sprayer, many of them plug the gun filter very quickly. As far as I understand, the glazes are sold for brushing on. How do you suggest to thin them for 1. air spraying; 2. dipping?

 

2. How can I deliberately create pinholes effect in Cone 5 commercial (Coyote) glazes/ electric kiln?

Pinholled shinos are of a particular interest, but I'd like to work with others as well.

 

Thank you.

 

Mike

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Not sure what the company would add to make them able to brush on. This could affect how you can troubleshoot this problem. You could try adding some deflocculant and see if that helps.

 

I read somewhere that shinos pinhole because of grog in the clay. If I forget to dust down my pots before glazing they get pinholes but it is not an exact science, just me being forgetful.

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+1 for Wyndham's suggestion of thinning with water and tossing the filter in the gun.

 

As far as your second question re deliberate pinholes, altering a commercial glaze to have a high loss on ignition (gassing out) to make pinholes would be next to impossible without drastically changing the glaze. The only other way I can think of would be to have no venting in the kiln during bisque firing, stack pots so there is little air circulation and fire quite low so not all the impurities in the clay have a chance to burn out. Then when doing the glaze firing fire quickly to your top temp and don't do a soak at the top. Might work.

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WOW that is interesting I am trying to get pinholes out of a chocolate brown clay I am using.  I use coyote chinos alot and I have never had any pinholes.  I had some crawling when it was put on to thick but they are pretty nice and reliable glazes.  Good luch I hope you achieve the effect you want.  I thought the piece was textured with some object to make it look like that.

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Guest JBaymore

Very interesting what John Britt did with my Shino glaze recipe glaze there!  I'd not seen that page. 

 

For closer to a Japanese pinholled shino look........ the START to the effect is the CLAY BODY, not the glaze.  Japanese Shino is done on an almost white, refractory, sandy slightly non-vitrified (by our standards) clay body.  It is fine grained but coarse copmpared to most western bodies......... our beneficiated commercial materials and high levels of stuff like ball clay make our clays "slick", greasy, and have high particle packing density.  Very "tight" surfaces.  Designed to be "defect free".  Most japanese bodies are NOT like this.  Pinholing in the west is a defect to be stamped out.

 

Find a white body.  Wedge in a bunch of fine silica sand.  A bunch.  Wedge in a bunch of EPK.  A bunch.  Make the form.  Let it get leather hard.  Take a metal scraper and scrape the surface to reveal the "grain" where you want pinholing.  Bisque it. 

 

You also now want a glaze that has a high liquid surface tension and a high alumina content.  Modifying a commercial glaze to this is tough to do with any accuracty.  Try by dumping in some alumina hydrate.  (measure liquid glaze and alumina amounts)

 

Where the clay is scraped........ you MIGHT get pinholling.  If the gods are with you.

 

best,

 

........................john

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