Alternative to bought moulds

[Sandera]

I was sure that I read somewhere that you could use ordinary crockery to slump glass in to. I have an old white (glazed) plate that I wanted to use (after I've drilled air holes into it) as it's a perfect size. Call me a tight beggar if you like but it seems criminal to spend heaps of money on moulds if I've already got something in the house. Can anyone reassure me that I'm not going mad and that this is possible?!

Help!

Sandera

[Lilley]

I think it is possible to use other things than bought moulds to slump glass over eg biscuit fired ceramic bowls or steel formers - BUT they do need to be coated in batt wash or equivalent or the glass will stick.  The problem I would expect if you use a glazed former is that the glaze (which is a thin layer of glass) will stick to what ever you slump in it unless there is some way that you can prevent this, but I don't know how you would go about that

[GaysieMay]

Would coating it in kiln wash work? 

[Sandera]

Not sure that kiln wash would stick but what about lining with kiln paper? - presumably you would have to have a couple of air holes in that as well?

Sandera

[Moreton]

You can use anything that has already been fired to a higher temperature than the temp you are going to fire the glass at. So, pretty much any pottery but if there is a glaze you really need to roughen it to give a key to the kiln wash that you will need to apply. Ideal way is sand blasting but a good scratch with diamond pads or even emery paper can work. Depends how hard the glaze is and how patient you are.

Yes, holes are required and thinfire paper wil work depending how severe any "bowlness" is. No need to roughen just dampen the paper and carefully "form" it to the curvature, any seams will show in the finished piece so the smoother the better.

Good luck & show us how you get on.

Pete

[Sandera]

Thanks Pete - will do. As a matter of interest if I use kiln paper why do I need to 'rough up' the surface of the mould?

Sandera

[Sandera]

Ooops - ignore my last question Pete. I've now correctly read your answer and understand what you mean.

[Zeldazog]

Just to back up what Pete says about ceramics that have already been fired higher should work - but personally, if I was using a glazed plate, I'd stick it in the kiln one time on its own, fire well above slumping temperatures, perhaps up to a full fuse, to make sure that the glaze doesn't soften and run (making sure your kiln shelf is well coated or got paper on, just in case)

Whilst some glazes are designed to go to the same temperature as the clay body they're being fired onto, occasionally very low temperature ones are used, which even with a good coat of kiln wash, could potentially run, so that's what I would do just to be on the safe side.

[Moreton]

Good point Dawn. If Sandera is near a potters supply firm (Potclays in Stoke for instance) then unglazed Bisque ware is good. It is cheap and ready to glaze with a nice matt surface & ideal for kiln wash. Lots of plates, bowls etc available.

Pete

[Sandera]

Thanks, that does seem sensible - I would hate to spoil a piece. Wish I did live somewhere near Stoke but think I might consider visiting the local ' Do it Yourself ceramic' place and see what they've got.

You're all geniuses!!

[Pat from Canvey]

You can also use anything ( provided it doesn't have undercuts) to make a clay mold as long as you can fire the clay to bisque beforehand. Kilnwash when cool and use as a slumping mold. The simplest way to use an old household plate, as Pete says,  is to sandblast it. Some stained glass studios have blasters they will hire out for an hour at a time. Then use kilnwash and use as a slump mold. I still have a ceramic kiln so firing to bisque is OK for me.

[Sandera]

I would love to have a ceramics kiln as well as a glass kiln - one day maybe

Good tip about the sandblasting hire - will have to look into that a bit more. I've not sandblasted yet - but I can see that this could be a really useful design feature for future projects.

[Pat from Canvey]

Theres always something like this for small items, http://www.amazon.com/Campbell-Hausfeld-AT1226-Sandblasting-Kit/dp/B0007D30DO
Perhaps those that have sandblasted beads can chip in here.

[Zeldazog]

That's just a gun, you need a compressor to add to that.... and personally, I wouldn't sandblast without a cabinet, as it would get everywhere, you need a mask and goggles too for safety.

[Sandera]

Interesting thoughts - I took a quick look at the link, Pat and was surprised at the low price although with the compressor (and presumably extractor, etc) this would probably start to get too pricey. I will certainly look at renting a sandblaster. Just wish I lived a bit closer the National Glass Centre in Sunderland - they've got great facilities there.