how close to the elements?

jackiesimmonds · March 11, 2015, 12:57:04 PM

I filled a pyramid mould, a big one, with frit yesterday, spent hours bashing up piece of glass and filling the cavity, then building up above the mould (it is a casting mould, to make a large paperweight). Carried it carefully to the kiln - Hobbyfuser - only to realise that when the clamshell top of the kiln closes, the top of the glass would be very, very close to the elements.

Nervous about this, I then carefully took the whole jolly lot OUT of the kiln again! This involved lots of spillage and hoovering, with curses.

How close can one come to the elements?

Fiona · March 12, 2015, 06:47:19 PM

I've just read in my kiln manual that you should leave at least 1 inch of space between the glass and the lid of the kiln.

jackiesimmonds · March 13, 2015, 07:10:54 AM

how intelligent, to read the manual! And thanks for the info. Means I have wasted money on the mould, how annoying. Bullseye recommend it be elevated on 2" posts, to ensure lots of air flow, and given that they also recommend building up above the top edge with loads of glass, it really is too big for the kiln I have.

ajda · March 13, 2015, 07:53:22 AM

Someone might be interested in buying that mould off you - possibly me, though I have one pyramid already. Which one is it and how much did it cost you?

Fiona · March 13, 2015, 10:31:33 AM

That's a shame. Like Alan said you could try selling it and then maybe get a smaller one.

flame n fuse · March 13, 2015, 11:09:14 AM

if you're meant to raise the base by 2 inches, it might be wise to also allow the same amount of space at the top, over the top of the piled up frit

jackiesimmonds · March 16, 2015, 08:33:46 AM

thanks for the replies. I took the mould into my college class on Saturday, and it is being fired in their big kiln with a front-opening door. No way my Hobbyfuser has enough clearance. If the piece turns out well, and I can find someone to do the polishing for me (I have a nasty bad back, cannot stand to polish for hours), then I will keep the mould and just make a few pieces to be fired at college.

If I don't like the result, I may well sell the mould. I do have a small pyramid, which makes nice small paperweights. However, much as I am enjoying learning about casting, and have quite a few ideas I would like to try, I have realised it is not an inexpensive option (quite the contrary given the cost of the casting glass) so unless I can produce beautiful pieces which have a decent resale value, (and sell) it is not going to be something I will do too often. There are only so many pieces one can have in one's own home!

ajda · March 16, 2015, 08:49:57 AM

Sounds like a good solution - would love to see... will you post some pics some day? Incidentally you might look into boron nitride spray as a mould release. It leaves a much better finish on the surface of the glass - on the other hand, once you've treated a ceramic mould with boron nitride you can't go back to standard the brush-on kiln-wash types as it penetrates the "pores" of the ceramic so that it's no longer porous and the kiln-wash type won't stick... Also it's expensive, though a little goes a long way.