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Devitrification of certain smaller parts

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Devitrification of certain smaller parts

Postby carolinemarbles » Wed Jun 27, 2018 12:37 am

Hi guys. Hoping you can point me in the right direction. Tried making reindeer in photo twice now. The first time there was devitrification just on one antler (the whole small piece of glass I had laid across another at an angle) and I thought maybe i hadn't cleaned that bit properly or something so tried another one. This time had it on two random antlers (see photo) The common factor is that they are the smallest parts so I'm thinking perhaps for this item I need to adjust some settings but not sure what I should adjust.

I'm using a Paragon SC2 with the window blocked up so even heat distribution. Tried the second one on thinfire paper instead of just a kilnwashed shelf so that's not it. Using the full fuse with Bullseye glass program as recommended by Warm Glass UK, but I do tend to skip the fuse at the 5 minute mark as everything is done by then.

222 per hour to 677 degrees c hold 30 min
333 per hour to 804 degrees c hold 10 min (I use 5 mostly)
999 per hour to 482 degrees c hold 60 min
83 per hour to 371 degrees c End

Do I need to reduce the fusing time a bit more (give it less than 5 minutes), reduce the fusing heat a little or could it be something to do with the time spent at other temperatures on the way up?

I know it's probably a case of trial and error but if someone could at least point me in the direction of the most likely culprit I'd be very grateful. I have the option of trying brown antlers instead but that feels a bit like giving up!
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Re: Devitrification of certain smaller parts

Postby marykaynitchie » Thu Jun 28, 2018 1:42 pm

Kilns fire differently, and if your process temperature is working at 5 minutes in, instead of taking 10, you can probably afford to reduce your process temperature. I would try cutting the process temperature by 10°C to start. If that is still working in 5 minutes, subtract another 10°C. (Consider making a test sample out of squares of glass that mimic the arrangement you have with your finished piece, so you don't lose any pieces that required lots of time and attention to make.)

You can anneal with a soak anywhere from 482-515°C, so it might be best not to change that on your next try, because you are already at the low end of that range. (If it is running hotter throughout the cycle, you might have room to change that, but I don't think it's necessary.)

Here are some links that might be helpful:

http://www.bullseyeglass.com/education/ ... asics.html

http://www.bullseyeglass.com/methods-id ... glass.html

To fix your devitrified projects, this method might help: http://www.bullseyeglass.com/methods-id ... flaws.html

Good luck! Let us know what happens!

Mary Kay
Mary Kay Nitchie
Bullseye Glass Co.

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