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Painting & Firing Bought Vases


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#1 Ads

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Posted 29 January 2008 - 03:39 AM

I want to paint & fire some vases (using Degussa enamels). I have done this before, but then I was using vases my friend had blown for me, so they were pretty solid. Now I have to use commercially made vases and I'm a bit nervous about how they'll react in the kiln. Does anyone have experience of firing bought vases? I'd be taking them up to about 560 degrees C (sorry, I don't know what this is in farenheit) and I guess I'd have to cool them a lot slower than my usual 'take it up to 560 then switch off' method of firing flat glass!


#2 Guest_Cappy Thompson_*

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Posted 29 January 2008 - 10:45 AM

QUOTE(Ads @ Jan 29 2008, 03:39 AM) View Post
I want to paint & fire some vases (using Degussa enamels). I have done this before, but then I was using vases my friend had blown for me, so they were pretty solid. Now I have to use commercially made vases and I'm a bit nervous about how they'll react in the kiln. Does anyone have experience of firing bought vases? I'd be taking them up to about 560 degrees C (sorry, I don't know what this is in farenheit) and I guess I'd have to cool them a lot slower than my usual 'take it up to 560 then switch off' method of firing flat glass!


Hello, I think I can answer your question...the commercial vases are probably fine to fire. They are likely to be made from a stiffer glass than your friend's because they are made for production. the annealing temperature is something you will have to guess about, but I would guess it's around 950 degrees F. Look on-line for a conversion chart.

If you have a set of polarizing lenses, you can check the glass for stress before and after firing. Here is a firing schedule that I use when I'm teaching. Using moderately sized even-walled vessels. Put a piece of thick fiber paper under the vase to insulate it from the kiln shelf.

Ramp slowly (4 hours) to 850 degrees F (longer for large pieces)
Hold at 850 for 1/2 hour
Ramp to 1100 F (or firing temp for your degusa enamels)
Hold for 3 minutes
Crash kiln to Annealing temp (950 F or what ever you discover)
Hold at Annealing temp for 1 hour ( longer for large or thick to thin pieces)
Ramp slowly (6 hours) to 400 F
Let kiln cool on it's own until you can comfortably touch the glass. You can put a brick in the kiln to prop open when it's under 200 F. Actually sooner, but don't shock it with a cold breeze.

If you are going to be painting vessels, you will eventually want to invest in a controller for your kiln. But commercial glass is pretty forgiving, so you can probably eye-ball your pyrometer and use the low-med-high settings to approximate the schedule.

Good luck!

Cappy Thompson
cappy@cappythompson.com

#3 Ads

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Posted 30 January 2008 - 04:49 AM

Wow, I've been a big fan of your work since I was at college & it was because I saw your technique that I originally decided to have a go at vase painting myself! [I finally got to see some of your flat-glass work up close at Derix studio a couple of years ago too.]
Thanks for replying!
I do have a controller on my kiln,but I just find it easier to take it up to temp then just end the programme as it seems to work fine on flat glass without an anneal. That's why this makes me nervous as I'm not used to it, and the glass isn't of even thickness so I'm glad to hear commerial glass is forgiving!
Will you be at the Festival of Glass at Stourbridge this year? I missed the masterclass you did in 2004.
Again, thanks for the help, I'll convert farenheit to degrees C and give it a go!
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