Why can't I melt my pot...er, I mean...

daffodildeb · Post by **daffodildeb** » Sat Feb 07, 2004 2:25 am

I'm trying a pot melt with 90 COE glass--mostly BE plain and iridized with a few little dichro fragments, etc. thrown in. I have some 2 1/2" bisque containers with holes--one round and one rectangular--suspended above a shelf. They were filled about 1/2 full with the scraps.

So why won't the glass do what it's supposed to do? I fired to 1500 and held for 20, and all I got was a little glass droplet at the opening of the holes, and a very thin bubble/crust at the top. It's finer than the glass used for fractures.

This is the first time trying this, and I thought I'd followed the recipe. Any ideas?

Mark Hughes · Post by **Mark Hughes** » Sat Feb 07, 2004 8:20 am

If you did a search in the archives you would find out potmelts need to be fired to 1650 F and a whole lot more info that you need to know so you don't waste time and glass.

Kim Bellis · Post by **Kim Bellis** » Sat Feb 07, 2004 9:04 am

Deb:
You do need to go higher in your temp. Give it time to "flow". I have heard that the dichro and irid lose there colors at this high temp. Can't remember where I read that.
Kim

Randy W · Post by **Randy W** » Sat Feb 07, 2004 9:52 am

Try taking it up to 1675Â° and hold for an hour and a half. Then anneal for 1/4" thickness.

Randy

daffodildeb · Post by **daffodildeb** » Sat Feb 07, 2004 9:45 pm

Thanks for the tips. I also had a nice conversation with "Tom in Texas" who's a few miles down the road from me. Guess I should have paid more attention to his pieces when I was in his shop last time.

At any rate, I'm trying again with a higher temp and longer soak. I'm not really holding out any hope for the dichro or iridized--they were mostly tiny bits too small to use on pendants.

daffodildeb · Post by **daffodildeb** » Sun Feb 08, 2004 8:58 am

So, okay, I tried it again. This time I went to 1750, with a 30 minute soak. I also added more pieces of glass to the pots, since they weren't very full and hadn't really melted anyway.

The glass all oozed out just the way it was supposed to. There was lots of sparkle since I had a number of scraps of green aventurine BE sheet glass, along with the iridized. Didn't see any of the dichro crumbs, but wasn't too surprised.

It was still at about 275 degrees when I looked at it closely. Of course I got the dreaded tink, tink, tink. I assume it was thermal shock.

The other possibility was incompatibility issues with the aventurine. Everything was BE or Uroboros 90, but I know that doesn't always matter. Also in the mix was some clear, clear with frit and streamers, the iridized black, some iridized clear, and a few miscellaneous pieces of blues, pinks, etc. Like I say, I was playing with scraps.

Of that unholy mix is there anything that doesn't like to play together?

daffodildeb · Post by **daffodildeb** » Sun Feb 08, 2004 9:00 am

P.S. I'd like to remelt this stuff at another time, perhaps with some different glass. I guess I have to grind/dissolve/soak off all of the shelf wash before I do that, right?

Patty Gray · Post by **Patty Gray** » Sun Feb 08, 2004 11:19 am

Hi Deb,

Thermal shock, 275 degrees and looking in....next time be patient and wait till your piece is room temp. For the Dichro, try capping it in a fuse before putting it into your pot melt. This may help with keeping the coating.

Good luck and have fun.

Patty
http://www.pattygray.com

Judy Schnabel · Post by **Judy Schnabel** » Sun Feb 08, 2004 12:24 pm

While we're on the subject of pot melts, I'm wondering what happens if you had a previous boo boo like thermal shock and you just shut the kiln off knowing your glass has split. You did not continue the full cycle, i.e. annealing the piece.

Now what happens if you put portions of that glass (unannealed) into a pot melt. Will you have problems?

Judy

Rebecca M. · Post by **Rebecca M.** » Sun Feb 08, 2004 2:55 pm

Deb, was the tink, tink, tink possibly from the glass left in the pot? Mine sometimes do that for hours after everything is taken out from a room temperature

kiln. Sorry, I used to be a Peeping Tomasina too. I sometimes think it's too bad. The dregs of the pot more often than not look much better than the top of the pot melt.

daffodildeb · Post by **daffodildeb** » Sun Feb 08, 2004 4:58 pm

Becca, yes there was tink, tink, tink (hereafter referred to as ttt) in the pots, but unfortunately it also was on the pretty sparkly stuff on the shelf. I removed everything in pieces. At least now I know that I can do a melt, and I have a good idea of the temps/time. This was my first, so I'm not bent out of shape. In fact, the only reason I got the ttt was because I WAS so excited and anxious. I don't do that with my fusing stuff.

Did anyone have an opinion of compatibility issues with aventurine glass? I didn't think there was that much in the mix, but the melt looked very green and sparkly--almost like pure aventurine sheet glass. It was about 4-5mm thick, and only a little clear showed in the piece, with no other colors.

Lynne Chappell · Post by **Lynne Chappell** » Thu Feb 12, 2004 2:05 am

BE marks their aventurine glass with compatible stickers, so I assume it shouldn't be a problem. Perhaps some of your scrap wasn't compatible? I know the fracture/streamer glass is never stickered, so maybe some of the other scraps were iffy as well. You could take a chunk of the broken stuff and do a test if you're going to use it in another piece, and you want to be sure.

Re the other question about glass breaking on the way up. If it breaks before strain point, then you don't need to anneal, it hasn't gotten hot enough. If it is above that, then re-annealing it is a good idea, otherwise it may be even more difficult to heat without cracking. Mine tends to blow up about 950, so I turn the kiln on and anneal before trying again.

daffodildeb · Post by **daffodildeb** » Thu Feb 12, 2004 4:05 am

Thanks, Lynne, but after talking to my buddy Tom in Texas, it appears that it's not a compatibility issue after all. And I had the same problem today with Spectrum that had nothing sparkling at all.

What's apparently happening is that the dams I'm using on the kiln shelf are sticking just a little bit to the glass in some areas, and the fractures are happening just at those points.

I'm afraid to do these melts without using some sort of dam, so I'm wondering about other options--feel free to chime in with suggestions. One possibility is to use a stainless dam with lots of shelf wash so it would separate better. Another possibility is to use some sort of shelf paper, at least where it meets the edges of the dam. In either of these ideas, I'm wondering if the temps would be too high (I've been going to 1750).

At least those were my thoughts until I read another thread about this just now.

Hmmm--just thought about another way to suspend the pots. What about stainless or tungsten rods from the welding shop, forming a crosshatched pattern, and allowing the glass to drip onto a wide dish? They would be suspending the pots only, so I wouldn't have to worry about contamination, and my AIM has different rings, so I could put them between layers. Would that work?

Any other thoughts? I'm just not having much luck with these things not sticking, and I haven't figured out another way of suspending them above the surface.

charlie · Post by **charlie** » Thu Feb 12, 2004 11:16 am

i'm having a hard time figuring out what you're doing. do you have any pictures of your setup?

the way i do it is:

cut out a circle of clear glass the diameter of what i want the melt to be.

weigh out the glass so that it will cover the circle of clear (1.6 lbs/sqft). add 10% for leftovers in the pot.

place 4 pieces of kiln furniture of the correct height around the circle.

use 2 pieces of cut up floor tiles to make a bridge between the furniture. arrange them such that they have a 1" slot between them.

place the pot on top of the tiles.

heat and anneal.

if you want to make something thicker than 1/4", then you have to dam. i use round steel rings i got from phil hoppes' son (see old classified). i line the ring with 1/16" fiber paper (not thinfire). the paper is reusable, so i keep it in a sealed jar between uses. you can use tile pieces, cut up shelves, etc. i'd wash them well and use fiber paper to line them.

Linda Denli · Post by **Linda Denli** » Thu Feb 12, 2004 2:18 pm

Hi Charlie - I'm going to try your method but would like to ask why you don't use thinfire paper to line the ring - also presumeably you use stone floor tile??

Best regards

Linda

charlie · Post by **charlie** » Thu Feb 12, 2004 2:31 pm

Linda Denli wrote:Hi Charlie - I'm going to try your method but would like to ask why you don't use thinfire paper to line the ring - also presumeably you use stone floor tile??

Best regards

Linda

thinfire turns to dust after the first use. i don't want to have to clean it up, as i can reuse 1/16" paper at least 3-4 times if i'm careful. one has to grind the outside of the disk anyway, so the texture doesn't matter.

i have lots of porcelain floor tile left over from when i did my house. this was fired at least at 2400F, so they'll take the 1650F well, and won't thermal shock. they're 16" squares, so i can get about 22" pieces if i cut them diagonally. i tried using leftover granite tiles, but they just deconstructed at 1650F. i make 3 8" pot melts at a time in my kiln.

daffodildeb · Post by **daffodildeb** » Fri Feb 13, 2004 4:58 am

Charlie, I can't post a photo of my setup because I don't really have one. What I want to do is a pot melt that I can later cut apart, OR have shaped in some respect when it melts. I've been talking with Tom in Texas, and he gave me some ideas using stainless steel.

Clearly the problem is the dam, and the reason I have it is because I want to prevent the glass from overflowing the shelf and damaging the kiln. In addition, I want a dependable way to suspend the pots above the shelf. What I have used, and what is failing, is the dam itself. The kiln wash is either not thick enough, or is failing, and whenever it sticks (even just a bit) to the sides, it's fracturing the glass. Not to mention the extremely sharp slivers of glass that reliably find their way to my fingers when I clean up.

charlie · Post by **charlie** » Fri Feb 13, 2004 10:33 am

using fiber paper will solve all the dam problems.

daffodildeb · Post by **daffodildeb** » Fri Feb 13, 2004 4:42 pm

Thanks, Charlie, I'll try it. I was steering away from it because of a thread that said it wouldn't work.

charlie holden · Post by **charlie holden** » Fri Feb 13, 2004 7:48 pm

I have written that fiber paper won't work. I should have been more specific and said it won't work underneath the glass. The glass will consume it as it spreads across the surface which will leave little incompatible bits in the bottom of your glass. Apparently Brad uses 110J paper under pot melts, but I've never tried 110J. I use plaster/silica. Fiber paper works well for dams.

ch