WarmGlass.com

I have a very small mold (about 4 inches across) with fluted edges. I have tried 4 different times, with different glass, to slump it and each time one side shrinks down into the mold making it lopsided. This last time I checked it at about 1110 and it was just starting to slump. I checked again at 1140 and it was too late I figure it is either that I am overfiring, or could it be that one side of my kiln is hotter? Any help is appreciated. Ya know, I am not even particularly fond of this mold but I am bound and determined to figure out what I'm doing wrong

Karon

kbarbour wrote:I have a very small mold (about 4 inches across) with fluted edges. I have tried 4 different times, with different glass, to slump it and each time one side shrinks down into the mold making it lopsided. This last time I checked it at about 1110 and it was just starting to slump. I checked again at 1140 and it was too late I figure it is either that I am overfiring, or could it be that one side of my kiln is hotter? Any help is appreciated. Ya know, I am not even particularly fond of this mold but I am bound and determined to figure out what I'm doing wrong

Karon

You have to level your shelf, your mold and your glass. And even then, it may slump crookedly. This is not unusual. You can try putting one of your failures back on the mold and try again. Or . . . you could accidentally drop the mold, and move on. Brock

Hi Brock, not sure that leveling is the problem because I have checked for that. Also it's as if one side the glass stays up and has these perfect little fluted edges and the rest just sinks in. Plus I had the very same problem in a different kiln. I do however love your idea about the "little accident" :-} Karon

Hi Brock, not sure that leveling is the problem because I have checked for that. Also it's as if one side the glass stays up and has these perfect little fluted edges and the rest just sinks in. Plus I had the very same problem in a different kiln. I do however love your idea about the "little accident" :-} Karon

kbarbour wrote:Hi Brock, not sure that leveling is the problem because I have checked for that. Also it's as if one side the glass stays up and has these perfect little fluted edges and the rest just sinks in. Plus I had the very same problem in a different kiln. I do however love your idea about the "little accident" :-} Karon

have you checked the flat piece set on the mold with a level? when i slump and don't want an asymetrical look, i check the glass in the mold in the kiln with a small level and nudge accordingly, moving the level to a couple of different spots on the glass....

is it always the same side that sinks in? is your piece the right size for the mold? i know the molds i have come with recommended dimensions for the specific mold....
D

Moving my slumps lower in the kiln helped me with this- i.e. away from the direct heat of the top elements of the kiln. Think slow baking rather than broiling.
Making the blank slightly larger than than the mold, like maybe 1/8" (Which translates to 1/4" total diameter). Not so big to droop over the outside of the mold, but enough to catch the mold edge and hold it. It will still pull inward because of the physics involved.
You don't mention the thickness of your blank, but when I've tried to do thin (1 or 1.5 layer) pieces what you described was almost guaranteed.
If you have uneven thickness in different areas of the piece itself, that could be contributing to your problem as well.
Possibly most importantly, I'd try going VERY slowly from the softening point of the glass to your target slumping temp (which may now be lower due to the slower ramp up=more heat work). Or maybe a soak right at the point where the glass is starting to loosen up. Temp varies with the glass of course.
HTH
Phil[/i]

Thanks to all of you for your suggestions and helpful tips. Karon