Silica sand between porcelain?

[Erika gof]

Hello everyone

I am experimenting with making really thin sheets of midfire porcelain paper clay sheets and they're working beautifully. I stacked them on top of each other in the bisque and they were fine but when I refired them to 1220deg c they stuck together slightly and as they were so thin I lost a couple trying to pry them apart. Could I sprinkle silica sand between each sheet or is this likely to stick to the sheets?

thanks in advance

[Min]

Do you use kiln wash and does the bottom porcelain sheet not get stuck to the kiln shelf? If this is the case then I would use kiln wash between the sheets. 

[Jeff Longtin]

Hey Erika,

When you say "trying to pry them art" what do you mean exactly? How did you pry them apart?

Another technique is to use heat/cold.  Rather than use an actual tool to "pry" them apart use warm water. The warmth will cause one sheet to expand, slightly, and they may separate easily.

This is how you separate teapot covers that stick "slightly". Fill the teapot with cool water than hold the cover end under warm water. If you're lucky you'll hear a slight "ping" and the cover will separate easily. The same method may work with your thin sheets. (Apply cool water to one side and warm water to the other. "Ping" and you have separation.)

If you go extreme and use cold water and hot water, in an attempt to speed the process, you'll probably hear "CRACK" and know you went too far.

 

[Erika gof]

Hi Min and Jeff

thank you both. I used Silica sand under them ( I stacked about 5 on top of each other) when I first bisqued them and everything was fine. I then refired to 1220 same way again but nothing between the pieces and they all fused together slightly. I was able to get them apart but broke a couple in the process.

I am wanting to go straight to 1220, not a seperate bisque and higher firing, but wondered if I can put the sand in between the pieces without them effecting them in any way. I imagine it will just dust off?

Jeff I like your idea but I think it might be a bit difficult as the pieces are like pages of a book, very thin and hard to do top and bottom I think.

[Bill Kielb]

1 hour ago, Erika gof said:

I am wanting to go straight to 1220, not a seperate bisque and higher firing, but wondered if I can put the sand in between

I would test, should be fine with the silica but I think I would default to alumina for more worry free separation. Watch everyone else’s wares though, easy to get this on other folks finished work. Folks often add Alumina to their wax for more control of the application however burning out large quantities of wax requires big ventilation so the alumina wax is a nice solution for keeping lids from sticking but probably not so much for separating sheets

Edited January 5 by Bill Kielb

[Erika gof]

Thanks Bill

 

[C.Banks]

crushed up and screened soft brick can work nicefly in a flour sifter

[Kelly in AK]

I saw Tom Coleman sift alumina on his kiln shelves. He said his porcelain would sometimes pluck (fuse) if he didn’t take that step.

 I had the thought of painting kiln wash thinly on pieces of newsprint and layering that between your porcelain sheets. It’s an idea, not sure how practical it’d be. 

[Bill Kielb]

45 minutes ago, Kelly in AK said:

pieces of newsprint and layering that between your porcelain sheets

Fire in the kiln? Could be a bit of smoke.

[Kelly in AK]

Definitely will smoke! 

[Erika gof]

Thanks everyone. Kiln is on with Alumina dusted between the sheet. Fingers crossed it works. Ill let you all know how it goes