Multiple slumpings in the same mould.

[Pat from Canvey]

I've used clay to make a mold but there are proprietory brands also. Have a look at, I think it's Alec Tiranti,
http://www.tiranti.co.uk/

[Lilley]

I've slumped two separate layers of glass over the same shapes at the same time.  I went on Jacqueline Cooley and Joanne Newman's sledge and slump course at Warm Glass a while back.  We made plaster formers and slumped glass over them.  I cut two circles of float glass and stacked them with plaster of paris in between.  They did separate, the inner one next to the 'mould' is sharper, more defined as you'd expect, but the top suface is affected by the plaster and glass above it and the top piece of glass is more rounded.  Obviously they do stack and Jacque and Jo had some pretty examples of float that they had layed up to make stacked vessels/sculpture.  The glass was 4mm thick.  You do have to be careful to cover all of the bottom piece with the plaster otherwise they will stick together forever! If you go to Warm Glass's page on facebook, https://www.facebook.com/pages/Warm-Glass-UK/121265261263687?v=wall and look for the sledge and slump course photos you'll find some pictures of what we did. If you look at the ones of the kiln set up in one of them you'll see on the left towards the back a circular looking arrangement - that was my double stack of glass.

[Glyn Burton]

You can use pretty much any clay to make a mould just bisque fire it. I tend to use a fairly high temperature say 1050c which will give a good balance between strength and porosity.

[Sandera]

Thank you for help and advice. Lilley that sounds like an amazing class. Do you have a photo of the finished pieces? Glyn -thanks - I can now advise my tutor. I assume you drill the air hole after firing and then smooth off? Pat thanks for the recommendation re tiranti - looks as though it stocks everything I need!

[Glyn Burton]

Make the air holes when the clay is leather hard its easier and then fire. do you want photos of the moulds or the finished pieces?

[Sandera]

Thanks again Glyn - that's what I'll do. If you wouldn't mind sending photos of both that would be great!

[chas]

On another note re slumping: I'm doing a short mould making course and the tutor is eager to personalise the session to include mould making for glass. I think the others on the course are ceramicists. I suggested that it would be useful if I could make a couple of slumping moulds. Does anyone know what material commercial slumping moulds are made of? Is it clay?

Well, the white ones are ceramic rather than clay I think... the closest I've got in a home-made mix is 50/50 plaster of Paris and silica. The first for setting and the second for durability. It gives a good smooth finish (if you want it) and rapid setting - though do allow thorough drying out to avoid self-destruction. Of the mould, that is.


Chas

[Lilley]

Chas, ceramic = fired clay