Line shows on opal borders

[CH Glass]

Once upon a time, there was a very imformative thread about this topic, but I think it's been lost. I'll ask again. Here's the scenario...

First layer: Clear glass blank as the base (say 8x8). Second layer: Something interesting in the middle in opal glass (say 4x4). Two inch opal border all around, in 2x6 pieces. All pieces fit together nice and tight. When it's full fused, I can see the lines where the border pieces have been butted against each other. How to I avoid getting these lines?

Thanks in advance for your advice.

[The Hobbyist]

"Flip and Fire"

Fire it face down. Flip it over and refire.

Jim

[haleybach]

Angle the cuts so there is slight overlap. Kind of like a side ways miter cut if that makes any sense.

[Tony Smith]

Can you see the lines because the piece has thinned out at the joint? This can happen with two layers if the glass is on the thin side. Another possibility is that the glass is moving slightly during heat up. Damming the piece would prevent the glass from moving. Adding a third layer, or using a 6mm base glass along with damming should eliminate both problems.

Tony

[Morganica]

All of the above, plus fire a bit hotter/longer. Opals, particularly the lighter colors, tend to be stiffer glass that needs more heatwork to flow and blend together. The problem is, getting the opals to flow means that the darker transparents, particularly black, will have been flowing for awhile, so they may start wavering.

That's why I sometimes prefire pale opals and whites and get them flowing, then go back and add in my darks in a second firing.

[Jerrwel]

Can you see the lines because the piece has thinned out at the joint? This can happen with two layers if the glass is on the thin side. Another possibility is that the glass is moving slightly during heat up. Damming the piece would prevent the glass from moving. Adding a third layer, or using a 6mm base glass along with damming should eliminate both problems.

Tony

CH Glass, have you seen Tony's work? He is the master of precisionhttp://www.blastedglass.com/newwork/img_1746.jpg. I'm always in awe when I look at his websitehttp://www.blastedglass.com/.

[CH Glass]

Sorry I have been delinquent responding. Thank you very much for all your advice!