Pot Melting tips required!

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EmmaPicton
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Joined: Mon Jun 09, 2003 11:51 am

Pot Melting tips required!

Post by EmmaPicton »

I have recently purchased an old ceramics kiln which I would like to use for Pot Melts. I am quite new to Kiln Glass and so far have had some good and some not so good results from it. The kiln appears to be extremely well insulated and cools very, very slowly. I have had some results from the kiln that have suffered from de-vit, and the results have also tended to stay quite thick and not spread as much as I would have liked.

If anybody has any pot melt tips they can give I would be most appreciative.

Thanks everyone.
PaulS
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Post by PaulS »

What kind of glass are you using Emma?

I use a small ceramic kiln for potmelts. See here how I set it up;

http://www.artemisglass.co.uk/studio5/s ... index.html

It's better to cool something very, very slowly that is going to last 2000 years. An extra hour or two is nothing. :)


Paul
It ain't where you're from, it's where you're at!
EmmaPicton
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Joined: Mon Jun 09, 2003 11:51 am

Post by EmmaPicton »

Hi

Thanks for replying, this is the first time I've used this forum and was convinced no one would respond!

The glass I've been using is the artista fusing range by desag and my kiln is quite a large front loader. Regarding the cooling time, I had thought the devit was due to being too high for too long, would it be worth opening the kiln to crash cool to the anneal point and then slowly over night to room temp?

Thanks

Emma
quill
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Post by quill »

HI Paul,

Great pictures on your website.

Can you tell me what type of metal wire you use to suspend your pot in the kiln?

Thanks!
PaulS
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Post by PaulS »

EmmaPicton wrote:Hi

Thanks for replying, this is the first time I've used this forum and was convinced no one would respond!

The glass I've been using is the artista fusing range by desag and my kiln is quite a large front loader. Regarding the cooling time, I had thought the devit was due to being too high for too long, would it be worth opening the kiln to crash cool to the anneal point and then slowly over night to room temp?

Thanks

Emma
There are people that have great knowledge of this,

Brilliant explanation of the fusing and annealing process for your type of glass here Emma but also useful anyone not sure about the process and why;
http://www.schott.com/architecture/engl ... nload.html

Download the Schott fusing manual here;
http://www.schott.com/architecture/engl ... ndex.html?

For questions or suggestions, directly from Schott here;
http://www.schott.com/architecture/engl ... index.html

If devitrification is a problem, I would crash cool from 820degC to just above the Upper Annealing Point say, 560degC. Then proceed into the annealing scgedule as usual.

If you have a front-loader try placing your shelf different heights from the floor.

Don't use your good glass until you have finished experimenting and don't crash cool unless you really have to cos it doesn't do the kiln any good; the brick has a different COE to the outer casing.

Hope this helps,


Paul
It ain't where you're from, it's where you're at!
PaulS
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Joined: Mon Mar 10, 2003 6:45 pm
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Post by PaulS »

quill wrote:HI Paul,

Great pictures on your website.

Can you tell me what type of metal wire you use to suspend your pot in the kiln?

Thanks!
Hiya Quill yes this digi camera is wikid. The kids let me borrow it occasionally, not bad considering it was me that bought it, eh?! I just have to book it a few days in advance.

The wire is regular nichrome wire, not galvanised. It's tied around the pot in one loop. Two wires are tied onto that. The long ends are then secured to the cage around the kiln. Good old Belizean ingenuity.

Soon as the long drip is finished, I turn off the kiln power and bravely lift the pot out the kiln. That way there is no 'umbilical cord' still attached if it didn't all drip out.

Then power up again and continue into the annealing ramp.


Paul
It ain't where you're from, it's where you're at!
PaulS
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Post by PaulS »

I can't download the pdf's from the Schott website Emma, just thought I'd mention that because I don't like recommending something then it doesn't work.

If enough of us mention it to the Schott people they might fix it though.

Good website apart from that.


Paul
It ain't where you're from, it's where you're at!
jim simmons
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Post by jim simmons »

Paul Stevenson wrote:I can't download the pdf's from the Schott website Emma, just thought I'd mention that because I don't like recommending something then it doesn't work.

If enough of us mention it to the Schott people they might fix it though.

Good website apart from that.


Paul
Hi Paul.. I just went there and the download worked just fine for me.

I am using netscape 7.0.

Jim
Jerry

Pot melt help

Post by Jerry »

You've raised two questions all us "Pot Melters" have had to deal with, and based on what has already been said, we all come to it our own way; here's mine.

First, the glass and devit. Most any glass will devit at these temps (1700 or so) even Spectrum series 96. Most fusing glass is designed to full fuse around 1450 - 1500 and at that range has different characteristics. When you push the envelope, expect some tears.

I beat the devit problem in a couple of ways, depending on what I'm doing and what actually happened. The easiest is to spray and refire. In every pot melt I've ever done, I needed to do a second firing to add a border or slump. And if iI added a border ther was a third firing to slump. At any of those points, give the disc a good spay of devit and most of your troubles will fade away, well, devit troubles anyway.

And on the note of devit; I use a lot of non system 96 Spectrum ALL of which tends to devitrify and fix it by spraying and refiring. I DO NOT agree with the idea of flash venting to cool below devit range. It's damaging to your kiln and any stuff you might have in there. (Brad, are you listening?) Devit isn't a problem to deal with later; busted kiln shelves are another matter.

Now you commented about the thickness. I learned, one night, that glass likes to get pretty thin if left on a kiln shelf, unattended, and at high temperatures. (This really happened) I set up a piece for raking so it would be ready in the morning. SLOW ramp up to 1700 from about ten in the evening to be ready at 5 AM. The piece was 14" square. Would you believe that a 14" square will grow to over 20" given enough time? I don't know how MUCH over 20" because that's the size of my shelf, and it dripped off on three sides. I've got some interesting "things" setting on a window ledge beside my kiln to remind me of all that.

The point is that if you let the pot melt drip and hold it at 1700 for an hour or so, it WILL flatten out to a very workable thickness. Sometimes I dam the melt (Hmmm, may have to change my phrasing) so it maintains a particular size or shape, but if you don't do that, just take it to process and hold.

Now, you will get a bunch of replies to a topic like yours and some will be different than others. That's good. This is, after all, a bit of alchemy! And wizards differ in the spells they cast.

Keep at it and drop a note from time to time so we can look at YOUR magic and wonder what sort of spell YOU'VE been casting.

Jerry
EmmaPicton
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Post by EmmaPicton »

Firstly, thank you all for your responses! I am finding them very useful.

Jerry:

When you talk about "spray" for the devit do you mean something like "Spray A Overglaze" I was unsure about using spray because I want to ultimately make tableware, and wasn't sure if this method may make my products unsuitable for holding edible items.

Would sandblasting the devit off work? Or would it come back?

I will have a go at soaking longer to make the glass spread more, I promise to let you all know how it goes and I'll put some pictures up for you!

It's time to go home now in the U.K. so I'll not be back at the computer until the morning, so don't feel I'm ignoring you all. I'll catch up with the posts soon so keep them coming in! :)

Thanks again for the advice.

Emma
Jerry

Pot melt

Post by Jerry »

Good question about the overspray; some do contain enough lead to make them suspect for serving food items. However, read the lable and find one that doesn't. I don't remember which name brand I use (memory is the second thing to go; wish I could remember what the first one was) but will check when I go back to the studio.

Your glass supplier should be able to answer that question. Devit spray is not much more than very finely ground glass suspended in alcohol.

Good luck,
Jerry
Cynthia

Post by Cynthia »

I'm repeating a lot of what you've already heard, but rather than pick through it...here's my response.

The devit is from being hot and hot for a long time and will show up more frequently with different glass colors. Crashing is hard on your brick, so I wouldn't advocate that since the devit can be remedied. If your puddle is remaining much thicker than 1/4" or 6mm, then I expect you aren't hot enough and holding long enough to let if flow and thin...which will be a demon for devit, but that's comes with the package at times.

I fire up to 1700 and hold until the pot quits flowing. I don't remove anything during the firing since I fugure I have to work the glass anyway after it comes out and don't want to risk damaging my kiln, my kiln brick or myself.

I would recommend that you sand blast off the devit and the shelf primer that probably will stick. You will be refiring the glass anyway, so these are good fixes. Apply an overglaze or flux (Superspray, which is ground glass in a soln, or Borax as a flux in soln) for the next firing to prevent further devit. Other overglazes such as Spray A contain lead which not only makes your piece not for food...but can react with other reactive glasses giving you a poopy brown you might not have wanted.

To suspend the pot over the shelf, I construct a bridge with kiln furniture and mullite strips that I cut from an old shelf. YOu can see an example of the structure, but for a different process. Remove the wire cage atop the bridge and put a pot on top of it and you'll get what I mean. This one also, doesn't span the shelf fully, but for pot drops I do use longer mullite strips to get it off the shelf.

http://community.webshots.com/album/62967227AfKlWJ

Put in 4 uprights that sit on the kiln floor. Span across 2 of those uprights with a mullite strip cut long enough to make the span and repeat with the other. Place them closely enough to support the pot, but leave a gap to center the drain hole over. I think this might be simpler than the wire configuration unless you already have a cage that will sit around your kiln. I fear there is a danger with the cage and nichrome configuration of making a connectin with the elements and electrocuting yourself or shorting out your kiln. Another reason I don't advocate removing your pot during the cycle, but that would be my opinion.

More advice than you could possibly sort through, but there you have it :D

Have fun, remain seated and keep your hands inside of the car at all times. :shock:
PaulS
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Re: Pot melt

Post by PaulS »

Jerry wrote:...I don't remember which name brand I use (memory is the second thing to go; wish I could remember what the first one was) but will check when I go back to the studio.
Ha ha ha Jerry I heard a good George Burns quotation on the radio the other day, you just reminded me, he said forgetfulness is a part of the ageing process;

first you forget names, then you start to forget faces, then you forget to pull your zipper up and the last stage -you forget to pull your zipper down! :)


Paul
It ain't where you're from, it's where you're at!
Jerry

Post by Jerry »

"first you forget names, then you start to forget faces, then you forget to pull your zipper up and the last stage -you forget to pull your zipper down"

Ahhhhh, I still have something to look forward to! Thanks Paul

BTW, are you coming to the WGW? Anyone with that kind of a sense of humor is someone I'd like to meet.

Jerry
PaulS
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Post by PaulS »

Jerry wrote:
BTW, are you coming to the WGW? Anyone with that kind of a sense of humor is someone I'd like to meet.

Jerry

Thanks for the invitation Jerry :) I'll send my address via pm and you can send the flight ticket there :D

But seriously, no Jerry.

Seriously. There's only one silver bird taking me out of this cold place, in one piece or as ashes.

Either way, I'll be sitting on my back step propping the door open, watching the toucans & butterflies, drink a little drink, smoke a little smoke, listening to the oranges grow.

Paul
It ain't where you're from, it's where you're at!
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