Box question

[Pat K.]

I recently bought a new mold - an elliptical shaped base and lid for a box. If you have the book "The Joy of Fusing", it's in there. I thought I'd practice with some smashed up glass from a broken piece since I've never really done a kiln casting before. Anyway, I like the way it turned out, but it does have some sharp edges which I've ground off. My question is "Can I take it to a fire polish without putting it back into the mold and without losing its shape or becoming a puddle?" Normally, I would just go ahead and try it to see if that would work, but the colors turned out really nice and I'd like to keep it. Any suggestions are appreciated. Thanks.

Patty

[Morganica]

Depends on how much heat is needed to polish up the surface again and how tall the box sides are in relation to the base. You'll most likely get some distortion and softening of edges. Glass will slump before it polishes, so it's tricky to get it to do the opposite.

I've done it with small castings, especially if, as with your box, the sides support each other and help prevent flopping over. I usually have to experiment with one or two castings before I find the right schedule for it. You might try making a throwaway box out of scrap, grind it a bit and test.

If you want to try, coldwork the ground areas to as close to perfect as possible. The less work the firepolish has to do, the sooner it will do it and the better your chances for success. Also, it can be difficult to match the coldworked surface area to the uncoldworked areas when you're limiting the heat, so you may find you need to coldwork at least the full face of the problem area to get it to look even after firing.

[nbobb]

Pat,
If you're talking about the Colour de Verre box mold the answer is, yes, you can put it back into the kiln for fire polishing without using the mold - Colour de Verre has detailed instructions for doing this on their website at http://www.colourdeverre.com/docs/33.pdf. Paradoxically, you have to do it this way because if you put it back in the mold you will pick up that mold texture again. I've made many of these boxes (mostly the rectangular ones) and have cold worked all surfaces, then returned it to the kiln to achieve either a high gloss or satin finish. The only problem I've encountered with doing this is the rectangular ones tend to warp a little at the corners as the glass flattens out. Another thing I've learned is to put more glass in the mold than their instructions say to because otherwise you get a 'bump' on the bottom of the box (which faces up in the mold) and you can diminish this bump by using more glass.

The firing schedule for this fire polishing is sort of a 'hit and run' method - the theory is to get it just hot enough on the outside to polish without causing the interior of the piece to soften.

[Pat K.]

Thanks Cynthia and Nancy,

I haven't tried firepolishing it yet, but will do so this week. Next time, I'll use more glass. I think my weight was off (too little), as my husband ruined our scale by putting it in the sink ; I didn't see it and turned on the water. I just bought a new scale yesterday so I'll be making some more - great Christmas presents.

I appreciate your help.

Patty