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Stiff adn soft black

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Stiff adn soft black

Postby jukka.sariola » Sun Oct 28, 2018 3:17 am

I tried to fuse white opalescent glass stripes with black stripes, but the bowl broke after firing. Must I use striff black insted of normal 0030 black sheets?
jukka.sariola
 

Re: Stiff adn soft black

Postby marykaynitchie » Mon Oct 29, 2018 3:38 pm

We would love to help you, but we need more information. viewtopic.php?f=14&t=4553

Please post again soon!

Mary Kay
Mary Kay Nitchie
Bullseye Glass Co.

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Re: Stiff adn soft black

Postby jukka.sariola » Tue Oct 30, 2018 3:36 am

Hi ! I have tried many plates with soft black glass and white glass. Like chess table and stripes. Every time they have been broken after normal firing program. I have worked 20 years with glass kilns and know that the firing schedule is OK. Once the piece broke after many days. And because it broke just in these lines between black and white I assume that the glasses are not suitable with each other. Must I use stiff black instead of soft 0030?
jukka.sariola
 

Re: Stiff adn soft black

Postby marykaynitchie » Wed Oct 31, 2018 8:54 am

A black and white checkerboard that breaks in firing is a classic example of design-induced stress. Please share your firing cycle. Then we will figure out how you can fire it successfully.

Thanks!

Mary Kay
Mary Kay Nitchie
Bullseye Glass Co.

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bit.ly/BullVideos
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Re: Stiff adn soft black

Postby jukka.sariola » Mon Nov 05, 2018 11:55 pm

Hi !
This is my firing scedule
1. 120` 520 1 `

2. Full 800 10´


3. Full 460 1 hour


4. Full 360 1 hour


5. End
jukka.sariola
 

Re: Stiff adn soft black

Postby Ted » Fri Nov 09, 2018 4:08 pm

Hello,

People routinely succeed in fusing 0100-30 and 0113-30 in stripe and checkerboard patterns. I think that there may be something else going on here.

Looking at your cycle (and depending on the placement of your thermocouple), your firings be missing the annealing range.

If we were firing 6mm of glass in our kilns here, this is more what the cycle would typically look like:

Time Temp Hold
140' 538°C 10'
20' 663°C 30'
25' 810°C 10'
Full 482°C 60'
120' 371°C 0
Full 21°C 0

I am confident that if you use this fusing cycle, the pieces will not break, unless the kiln is not capable of cooling uniformly.

For more on annealing in general, you might be interested in checking out this presentation: http://www.bullseyeglass.com/education/ ... glass.html

Thank you,

Ted
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