Bottomless Molds - traditional slumping method?

[Deive Butvila]

Has anyone ever used bottom less slumping molds?

I am wondering how heat escapes from these bottomless molds that sit directly on the kiln shelf, and if there are any special firing considerations. I don't see anything on the seller's web site about needing to do anything special with these molds.

The only slumping molds I own all have heat escape holes in the bottom. I put these on short kiln posts when slumping. All very straightforward.

Thank You

[Valerie Adams]

I'm guessing you're talking about Laurie Spray's molds. She will supply detailed firing schedules for you to start with. Most of her molds are fairly shallow; I've got one that I just use as I would any other. Many of my shallow molds don't have holes drilled in them anyway. But I'm a big advocate of 'low and slow' for my slumping.

[Laurie Spray]

We have been making our "Bottomless Molds" for almost 10 years now. They are fired just like you would any other slumping mold but you are guaranteed to always have a non rocking floor to your glass creation when using them. I got very tired of rocking bottoms on art pieces that were slumped onto molds that were basically made for the ceramic industry......and then just renamed glass slumping molds. We now make these molds from 4" to 18". Along with Valerie.....low and slow is the best way to slump.....but you can also slump and fire polish at the same time in low profile molds. Let us know if you have any questions.

[rosanna gusler]

The holes are to allow air to escape. Not heat. R.

[Deive Butvila]

The holes are to allow air to escape. Not heat. R.

Yes, thank you for the correction.

[Deive Butvila]

I guess I did not realize these are shallow low profile molds so not having vents makes some sense to me. I just have not had any experience with ventless molds.

Thanks to all for educating the newbie!

[rosanna gusler]

The fact that they have no bottom means that yes they are vented. Air can escape between the mold and the shelf. If it will not hold water it will not hold air. R.

[Morganica]

Just think of those center holes as great big vents...