WarmGlass.com

greetings, and thanks for all the pot melt pics and info,,,,,,,,,what im wondering is *do you need to prefire the mold when doing a pot melt? *does the glass flow easily once it hits of mold, or does it sit there for a while, before going to the bottom? thanks, rodney

Hi Rodney,

I just go ahead and load the pot with glass, soak the mold at 250 and then 350 to dry it, then go on up. I hold a little bit at anneal temp to warm up the inside of the mold before the glass starts dripping into it. I usually design in a shallow feeder gate, so that if the pot drip starts to go faster than the glass can move down into the mold, there is some place where the extra can wait. That's my input, anyway. Hope it helps.

Steph

thanks for the info on that,,,*lets say that the pot has three pounds of glass, in strips, can you tell me at what temp the glass actually starts to flow out, and how long will it take for the pot to empty, and and what temps these things start to happen,,,,,,*on you idea of the feeder thing to catch the glass from the pot and will then feed the mold, would this probem be solved if the hole in the pot was smaller?,,,,would the shape of the pot make a difference, would more ofa cone, rather than a flat bottom make a difference?,,,ok,,,thanks so much for the help, this pot melt thing is really great, i love seeing all the pics, keep up the great work,,,rodney

Hi Rodney,

I know that theoretically the more cone-shaped the feeder gate is (whether built into the mold itself, or in the form of a crucible) the easier it is for the glass to flow down & out the hole. But on really wide molds I've used flower pots with a 6 or 8" flat bottom, and if you wait a while everything drips out fine. There is always a little left in the pot, but not enough to worry about.

I know that some people don't build a feeder gate into their mold, they just use a crucible. Personally it makes me a little bit nervous, but that's probably just me. The speed at which the glass can move down into the mold cavity is going to depend on how large or small the mold cavity opening is. I'm casting vessels with a 1/4-1/2" wall, and so it takes a bit of time for the glass to be able to make its way down into those small spaces. If the mold is for a solid piece, then you probably wouldn't have any problem at all, the glass would just drop to the bottom of the mold no problem.

I'm casting with lead glass, so the melt temp is a bit lower. Bullseye or Spectrum should melt fine at 1550. Depending on how fast you can ramp up from around anneal temp to the melt temp, the pots should start to drip in a thick-looking rope as it gets close to melt temp. As the glass soaks at melt temp for a longer time, the glass will get runnier and will start to flow in a thinner, faster stream.

If I have around 10# of glass in a pot, it usually takes something like 5 hours or so to empty the pot so that there is just a very thin stream dripping out.

I don't think I'd make the hole in the pot smaller, although the small pots I think have only about a 1/4" hole or something like that and they still drip fine.

Did I answer everything? Post a pic to let us see what you're doing!
Steph

hey there,,thanks for the info, my email is ROVAHART@AOL.COM, would you send me you site address, id like to see what you are doing, im busy now with this other project, but want to get my ducks in a row with the pot melts before i actually do it,,,,on your molds, are you using the BE kilnwash to coat the inside, im wanting to do something that doesnt require alot of coldworking?,,,,*i was talking to this jewelry guy who said something about the jewelry casting investment being a possible choice...ok, thanks for the info,,,,slowly but surely,,,rodney

Rodney, I did a pot melt in a class a couple of months ago. You don't need to coat the inside of your pot for a pot melt. All you need is to use a disposable clay flowerpot with the hole in the bottom (and depending on how impatient you are you may want a bigger hole though that will change the size of your striations). When all is done you will have a flowerpot with a thin layer of glass fused to its bottom and because the glass and clay are incompatible it will be crazing like crazy! But on your kilnwashed shelf you will have this wonderful spirally creation. (And Dani if you read this, I think the oval shape comes if the kiln shelf is tilted to make the glass flow down some -- that's what we did with Roger Thomas). Frankly I think the real beauty in a pot melt comes when you slice the melt. There are tons of thin thin layers of color in interesting patterns.

Barbara