Porcelain slip blisters

Aymen
New Member

Posts: 10

Porcelain slip blisters Jun 19, 2017 1:20:56 GMT -6

Quote

Post by Aymen on Jun 19, 2017 1:20:56 GMT -6

I have been facing a blistering problem on some of my experiments lately ........... any advice.

I use a stoneware body that I cover with a porcelain slip it works 50% of the time but I am getting too many defects on the surface.

the slip was brushed on while leather hard and left to dry together.

I started pouring the slip on the surface (no results out yet)

when breaking the the blisters a powdery substance comes out from underneath the glaze ...... and the stoneware body is intact

drive.google.com/file/d/0B9g0TVON-fuhQlA5N3ZJaDRlNGM/view?usp=sharing

drive.google.com/file/d/0B9g0TVON-fuhMWVOWmdvNHBzRDQ/view?usp=sharing

www.dropbox.com/s/565usr1t951rm0w/IMG_3367.JPG?dl=0

Last Edit: Jun 19, 2017 1:22:55 GMT -6 by Aymen

Arnie Benton
Moderator

Posts: 204

Porcelain slip blisters Jun 19, 2017 9:33:23 GMT -6

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Post by Arnie Benton on Jun 19, 2017 9:33:23 GMT -6

I don't know what's going on with your blistering - I haven't had problems using a porcelain slip over a white stoneware body - difference is that I brush the porcelain slip over bisqued pieces - and then refire to about cone 06. I never tried applying the slip to greenware. An extra step, but maybe I've been unknowingly avoiding problems.

Arnie

mohawkpiper Administrator Posts: 274	Porcelain slip blisters Jun 19, 2017 10:14:10 GMT -6 Quote Select Post Deselect Post Link to Post Member Give Gift Back to Top Post by mohawkpiper on Jun 19, 2017 10:14:10 GMT -6 i put slip on greenware. i do it when its bone dry. when i used to brush it on i got blisters too. now i spray it on and it works well as long as i dont spray on too much. i bisque a little higher, to cone 04. G
	animator by day, potter by night

Aymen New Member Posts: 10	Porcelain slip blisters Jun 20, 2017 0:49:15 GMT -6 Quote Select Post Deselect Post Link to Post Member Give Gift Back to Top Post by Aymen on Jun 20, 2017 0:49:15 GMT -6 I just opened another kiln, I have less blisters "one crawling spot" but that could be some dust. I will try both methods spraying it on while bisque & bone dry thank you

tileman2
Senior Member

Developing R2 porcelain clay body specifically designed for crystalline glaze.

Posts: 396

Porcelain slip blisters Jun 20, 2017 7:59:37 GMT -6

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Post by tileman2 on Jun 20, 2017 7:59:37 GMT -6

The fact that you have powder when you break open the blisters, tells me the slip is under- fluxed. If you are putting it on green ware, then dust would not be the other issue. Add a tablespoon of Nep Sy, or other KnaO fluxes you have around to one cup of slip. Do not use lithium, magnesium, or calcium. Run a test piece and check it. If blisters are gone, then your good to go. If there are still a few, then and 1.5 tablespoons. If it were simply an off- gassing issue, there would be no dust. Dust= no flux to vitrify.

Tom

Aymen New Member Posts: 10	Porcelain slip blisters Jul 10, 2017 11:11:36 GMT -6 Quote Select Post Deselect Post Link to Post Member Give Gift Back to Top Post by Aymen on Jul 10, 2017 11:11:36 GMT -6 Thank you Tom I will try this

Post by Aymen on Jun 19, 2017 1:20:56 GMT -6

Post by Arnie Benton on Jun 19, 2017 9:33:23 GMT -6

Post by mohawkpiper on Jun 19, 2017 10:14:10 GMT -6

Post by Aymen on Jun 20, 2017 0:49:15 GMT -6

Post by tileman2 on Jun 20, 2017 7:59:37 GMT -6

Post by Aymen on Jul 10, 2017 11:11:36 GMT -6