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My slump conumdrum is regarding smallish bowls:

I am making some dinnerware. I can slump the plates (dinner & salad) okay, but I'm thinking I need a different schedule for the bowls. I think they are sliding down too far in the molds and I'm losing the rims.

The details:
The bowl blank starts out at 6.25" and ends up at: 5.375" after slumping into a 1.75" deep bowl. (This is BE two layers, already fused)

My schedule is:
400° to 1166° hld 5 min
9999 to 1300° hld 20 min
9999 to 960° hld 30 min

Am I over doing these bowls?


Thanks.

Carla

Hi Carla,

You may have better results by a longer hold at the lower end of the slumping range. It's hard to say with the small size of the bowls, but maybe try:

400 dph to 1150
100 dph to 1250
9999 dph to 960

Brock

There is a lot of different ways of slumping

Some of the contardictory

Try a search on in the archives

Baffle n Go

Zap n Blastem

U might even try n go slower than Brock suggested after 1150

Add a half inch to the diameter of your blank. You can overhang the rim of a mold by a quarter inch or so and it will usually still end up slumping down into a bowl mold.

If you look at the slump when the temperature is around 1000 F and the slump is just beginning, you will likely see that the center is beginning to drop but the edges are lifting up. The difference between the two is that the center is much further away from any support and so feels more force pulling it down. It is usually hotter than the rim as well, as it isn't next to the mold. The mold takes some of the available heat away from the glass that touches it around the rim. Often the rim will slip down into the mold during this phase of heating.

I do a lot of large drop outs for bowl shaped light fixtures hung from ceilings. To make a 24 inch bowl I use a 25 inch mold with a 4 inch rim, (33 inches across all together). I use a square blank though, with a minimum of 4 inches of rim on the sides and 7 or 8 inches of rim out to the corners. I've looked in and seen the edges of these glass rims raised 4 or 5 inches off the mold before they slump back down flat. The glass will usually slide in to the center, marking up the half inch of glass just inside the mold edge. So I trim off that half inch and cold work the rim. Without that much extra glass to counterweight the glass in the center of the mold, the glass will often fold up and fall through the center hole.

charlie holden wrote: Without that much extra glass to counterweight the glass in the center of the mold, the glass will often fold up and fall through the center hole.

And, when that happens, any neat tips how to flatten it at all evenly? I have a piece that looks like a canoli with air for the filling

Jo

Jo wrote:

charlie holden wrote: Without that much extra glass to counterweight the glass in the center of the mold, the glass will often fold up and fall through the center hole.

And, when that happens, any neat tips how to flatten it at all evenly? I have a piece that looks like a canoli with air for the filling

Jo

When that happens, you add the glass to the scrap bin and plan on doing some high-fire plates and bowls someday.

Ron

Ron Coleman wrote: When that happens, you add the glass to the scrap bin and plan on doing some high-fire plates and bowls someday.

Ron

I have what I call a fritalator. Sort of like a large hammer that fits into a pipe that has fritable glass inside. I think Carol posted a picture of hers a while back.

Of course Jo could always do a series of pasta inspired sculpture.

Jo wrote:

charlie holden wrote: Without that much extra glass to counterweight the glass in the center of the mold, the glass will often fold up and fall through the center hole.

And, when that happens, any neat tips how to flatten it at all evenly? I have a piece that looks like a canoli with air for the filling

Jo

Jo, I think a glass canoli sounds totally awesome! You should tell people you did it on purpose. It's, er, a napkin holder or, something.... or you could melt it again-fold one end or the middle and make a vase.

All my drop out flops are just weird looking puddles, with stalagmites on top. They don't even make good frit. Fortunately it doesn't happen much.

charlie holden wrote:

Ron Coleman wrote: When that happens, you add the glass to the scrap bin and plan on doing some high-fire plates and bowls someday.

Ron

I have what I call a fritalator. Sort of like a large hammer that fits into a pipe that has fritable glass inside. I think Carol posted a picture of hers a while back.

Of course Jo could always do a series of pasta inspired sculpture.

Somehow I knew there wasn't gonna be an easy fix to this

I'll work on Strega's "I planned it this way" but I'm afraid the hammer or high-fire will be what's next.

Some accidents are happy...this one is the don't-do-that-again kind.

Jo wrote:Somehow I knew there wasn't gonna be an easy fix to this

I'll work on Strega's "I planned it this way" but I'm afraid the hammer or high-fire will be what's next.

Some accidents are happy...this one is the don't-do-that-again kind.

The real trick is never tell anyone what you're making till it's finished.

Ron