irregular edges

[ncbill]

I couldn't find any reference to this, but I must not be searching with the right words. I am making a small 5" square dish with Spectrum 96 glass. The base is white, and on top of the base are six rectangular pieces forming two rows of three pieces each. The top pieces are large enough that there is a 1/8" overhang on all 4 sides. I cut and fit the pieces carefully together and fuse them with the smaller, white piece, on the bottom, at 1460 for 10 minutes. There are two things I would like to eliminate.

First, when the piece is removed from the kiln, there is often a notch between two pieces where they meet along the edge of the piece. This is more pronounced on the edges where only two pieces meet. I can reduce or eliminate the notch with cold work, but it would be nicer if it didn't happen.

Secondly, sometimes there will be a thin light colored line between two pieces along their common edge. Usually, one color stops and the other begins very smoothly, but on occasion this line appears. There is no visible devit on the surface, but the line is annoying. I have not yet tried a longer soak time, as the surface is very smooth at the joints.

I welcome suggestions on eliminating these annoyances. As I can't find references to them, they evidently don't happen often to others.

Thanks

[Brad Walker]

Cut the pieces the same size as the bottom piece and the notches should not appear (or at least not be so pronounced). They're caused because the pieces that overhang are only one layer of glass and each color piece draws up differently. If they're not exactly the same size the effect is more pronounced.

Is the line between pieces a brownish/dark reddish line? Is it mostly between warm colors (yellow, orange, red) and cool colors (medium blues and greens)? If so, then it's a reaction between the chemicals in the two glasses that shows up as a line when they touch. You can't prevent it, only avoid that color combination or learn to love it (many people do) and use it in your pieces.

[ncbill]

Well, the 1/8" overhang is in your book, but I can see that it would work better with a single top piece. Better to have the smooth edges and expect to need to smooth off the bottom edges a bit, I guess.

And, yes, the line is between blue and red, so I'll be aware of that for future projects.

Thanks

[Jerrwel]

First, when the piece is removed from the kiln, there is often a notch between two pieces where they meet along the edge of the piece. This is more pronounced on the edges where only two pieces meet.

Secondly, sometimes there will be a thin light colored line between two pieces along their common edge. Usually, one color stops and the other begins very smoothly, but on occasion this line appears.

Thanks

What Brad said, but also you might try the 'flip and fire' process of starting with your triangles as the base with the larger piece of glass on top. The design is always (usually?) more precise when fired design down; of course this requires a second firing to 'fire polish' the top or requires that you coldwork the top. I assemble by pieces outside of the kiln using tiny dots of hot glue to hold things together and then transfer the piece to the kiln up-side-down.