My first pot melt.....HELP!

[deborahbur]

I used mostly clear glass with some green and yellow. I used a skutt 1027 kiln and ramped it at 650 up to 1625. Held for one hour and annealed.

I got a small pot melt, show in photo, but most of the glass didn't melt and stayed in pot. Pot cracked. Also, the pot drop pulled all the kiln wash off the shelf and I can't get it off the back of the glass. The glass was all bullseye 90 coe.

What did I do wrong.

The glass left in the broken pot was beautiful but cant' get the pot off the edges of the glass to use the glass again.

http://albums.photo.epson.com/j/ViewPho ... 475073&f=0

You can look at my pot drop here.

Thanks for any help

Deborah[/img]

[Randy W]

I have found that you can only use the pot once. They are cheap and disposable, I usually find a 6" pot for less than a dollar.

I use a 6" pot with about 50 ounces of glass to get a 12" disk. I weighed the pot before and after firing and found that 4 ounces of glass remains inside the pot. You can't resuse the glass from the pot. It's stuck there forever.

Did you enlarge the hole in the bottom of the pot? If not it will take a loooooong time for the glass to drain out. I make the hole at least 1" in diameter. (that's 2.54 centemeters) I have found a speed bit on my old Wizling grinder does the trick to open up the hole. You may need to hold longer than an hour. Keep peeking until there is just a thread of glass comming out of the bottom. When it gets to that point, I put on my protective gear,heavy denim jacket, welding gloves and face shield, shut off the kiln and reach in with a tongs and carefully but quickly remove the pot. Let the kiln cool to 1050°. Close the lid and heat back up to around 1450°. This step allows the air bubbles to heal over.

You need to use LOTS of kiln wash on the shelf. I apply at least 12 coats. ( I use hotline) Most of the wash sticks to the back of the piece but "usually" comes off with a razor blade and a little scrubbing. Although I do have a couple of pieces that it really stuck on there and I can't figure out why. Same firing schedule, same brand of glass, I'll have to sand blast it off.

Give it another go. My first potmelt didn't turn out either. It stuck to the shelf and crumbled apart.

Randy

[Lisa Allen]

I haven't done a pot melt yet, but the information that I have compiled seems to suggest going hotter than you went, especially if much of your glass is still in the pot. One of my notes says 1650 for 30 min and the other says 1700 for 40 min. I'm not sure who posted these temps and times, but they were from successful pot melters, so you might try going hotter to get more glass to drip out.

Lisa

[Cynthia]

I used mostly clear glass with some green and yellow. I used a skutt 1027 kiln and ramped it at 650 up to 1625. Held for one hour and annealed.

Go to 1700 and hold 'til the pot it's empty, or quits flowing.

You will get more dramatic results if you charge the pot with three colors that are contrasting. As an example, charge one side with an opal orange and the other with cobalt blue. Divide the two with a transparent...or use orange and blue transparents and divide the two with white opal.

...most of the glass didn't melt and stayed in pot. Pot cracked. Also, the pot drop pulled all the kiln wash off the shelf and I can't get it off the back of the glass...What did I do wrong.

You didn't do anything wrong. At those temps the kiln wash will stick, particularly to the opals. Hotline makes a high temp kiln wash you could try to see if it sticks less. Coat the shelf with several layers just to be sure your shelf is well protected.

You can blast the pot away from the core of glass that remains. I like what's left in the pot and that glass makes wonderful inclusion glass. Cut through it with a tile saw and see what the core is like. It can be rather interesting.

To get the wash off of the pot melt puddle, soak it, scrape with a razor, scrub with a tuffy, try Wash Away or Sulfamic Acid, Vinegar, Lime Away or CLR...all of these can discolor some glasses, so you might want to try elbow grease first...then you can always have that side sandblasted too.

[Jerry]

I've been tampering with pot melts enough to spot a couple of problems in what you said you did, but the others got there first. I've got a Paragon front loader and don't trust the temperature readings, so I like to go to 1700 with about a two hour hold.

Once I see a very fine thread of glass under the pot I dress as you've already been advised to dress, but go in with an old, rusty, very heavy set of cutters, cut the stream close to the glass and then get the fireplace tongs, shut off the smoke detector and pull the pot out.

Now, one lesson about heat in our kilns; Don't block it! If you have a top loader, whatever you have holding up your pot, and the pot itself, are all in the way of the heat. Get them out and crank it back up to 1700. Your disc will flatten out, bubbles will fade and the day will go well.

I like a larger opening too. But my favorite trick is to change the SHAPE of the opening. You're on you own there, but get creative and keep lots of notes. BTW, if you remember what glass you used in what pot, you CAN use them over and over. I've never lost one due to heat fracturing yet. The only one I lost was the one I dropped, and yes, it was hot.

CU
Jerry

[Steve Immerman]

Your first pot melt looks just like my first one. I agree with everything everyone else has posted.

I found that the kiln wash did stick to the back of the piece, and that sandblasting it off worked well. I don't think I could have gotten it all of without the blaster. I also blasted off any devit before each subsequent firing.

My successful one was fired in a 6" pot, 7/8" hole, 1700 degrees until just a thin stream of glass was flowing - it happened to be about 40 min at that time.

Try again. You'll get it to work.

Steve

[quill]

>Also, the pot drop pulled all the kiln wash off the shelf and I can't get it off the back of the glass<


I have only been fusing a short time but am planning a pot melt and was wondering if using shelf paper and instead of kiln wash would work better?

I thought I could cut a larger piece than I need and wrap it under the shelf.

I thought if I tucked it between the kiln posts and the shelf it would not curl up on me. Has anyone tried this? Or is there a reason for not using shelf that I am not aware of?

[Jackie Beckman]

I thought if I tucked it between the kiln posts and the shelf it would not curl up on me. Has anyone tried this? Or is there a reason for not using shelf that I am not aware of?

This sounds like you plan on using thinfire (curl up) and I don't think that will work. It isn't meant to withstand 1700 degrees like you'll need to go to for the pot melt

[Jerry]

Thin fire won't work It's too fragile and moves around at 1700 under the weight and movement of the glass. Don't wimp out; use good quality shelf PRIMER applied left and right, up and down, and on the diagnals. Eight coats should be enough. And of course some of it will stick. But some hot water, steel wool, elbow grease and patience will deal with it. Unless, of course, you are fortunate enough to have access to a blaster. If all that doesn't work, try some CLR in hot water with the steel wool, and then progres to muriatic acid and steel wool. CLR isn't too bad but the muriatic acid isn't too much fun. It will take off the kiln wash, make the front of the glass look like it was devitrified and do some wonderful things to the open cuts on your hands; uhhh, you are a glass crafter? You do have open cuts don't you. Yeah, rubber gloves help.

Good luck,
Jerry

[Cynthia]

...was wondering if using shelf paper and instead of kiln wash would work better?

I thought I could cut a larger piece than I need and wrap it under the shelf.

I thought if I tucked it between the kiln posts and the shelf it would not curl up on me. Has anyone tried this? Or is there a reason for not using shelf that I am not aware of?

In my experience, some of the small ceramic fibers will get imbedded into the glass at those temps. This is harder to remedy than removing kiln wash. Been there, done that...prefer the kiln wash over fiber mess. Thinfire won't hold up at all under those temps no matter how you wrap it.

I just think you will be better off with a properly primed shelf.

[quill]

Thanks for the tips. I didn't know the shelfpaper would wimp out at high temps.

you are a glass crafter? You do have open cuts don't you

I almost always have cuts or burns, usually both, I am afraid.

[Judith Andre]

Why is it necessary to take the pot out? Haven't tryed a pot melt yet and don't like reaching into a hot kiln if I don't have to. It is very awkward in gloves that are way too big .....can't find any to fit.

[deborahbur]

I didn't take the pot out and it came out great!

[Colin & Helen]

Why is it necessary to take the pot out? Haven't tryed a pot melt yet and don't like reaching into a hot kiln if I don't have to. It is very awkward in gloves that are way too big .....can't find any to fit.

Pot melts are a bit like crucible casting ...and with casting I always remove the crucible with Raku tongs( Raku is a type of pottery) .. the only reason I do this is so that last fine thread of glass that was attached to crucible has some chance of smoothing over.. but in short I really don't know if it is really worth all the effort..Colin

[paulfjackson]

I just did my first Potmelt after reading all of your comments. I ramped at full speed (since I didn't care if the glass cracked in the pot) up to 1600. The glass started pooping out the standard non-enlarged hole at 1500. At 1600 I soaked for an hour. About 1/2 the glas had come out, so I did another hour at 1600 (Spectrum glass, by the way). Ater the second hour the drip was not moving and not emptying, so I ramped up to 1700 and another hour soak. That got things moving! The drip was thinner and
eventually stoped and seperated itself from the pool. There is very little glass left in the pot, and it looks like I could probably use it again. One thing is for sure, My kiln is not sitting level!!

[Clifford Ross]

Paul- a question. How bad was the devit on your piece? Thanks

[Haydo]

Pot melt and vitrograph work is as about as exciting and proactive as my studio gets at present. Your kiln looks like it could handle supporting the pot higher which would cop more heat and the glass room to move as it drops. As mentioned the hole size can change things, one no muck around way to make them is with a engineers ball pien hammer(small one).- Haydo