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I've had kilns for many years and used them to cast glass that I used for my bevel work in my leaded windows. Just recently I've been fusing work for plate and bowls and am really enjoying it. Naturally I've been viewing other work and am especially taken with strips of color and clear glass fused together and then slumped.

I've learned to fire the eventual good side down first when fusing and that side's lines are perfect. It seems no matter how tight I get the pieces the lines on the up side won't be straight. Recently I spent the better part of a day grinding the pieces for a small circle. Every piece was ground top and bottom so a straight edge placed on them showed no gaps. And just for good measure, I ground both sides of every strip so they would fit together as tight as I could get them. They were secured in a ss form with 1/8" fiber paper around the inside and believe me when I tell you, the pieces of glass were in there pretty tight.

Yet when I took it out of the kiln, the side that faced up had wavy lines. What the heck? With opalescent glass, it's not so bad as you can't see the back from the front but with clear, it's major suckage to see those lines

I've been beveling/engraving glass for almost 50 years and consider myself a master beveler so it can't be the grinding, it must be the process.

I look at work like Hegland Glass and their clear lines look perfect-how in the world do they do that?

glass moves with heat so perhaps slower and lower temperatures and less total heat work than you are currently giving the glass you are using will allow it to remain straight lined.

My 2 cents. The glass facing the shelf will stay the way you made it, It does what you tell it to do. The glass facing the inside of the kiln will do what it wants to. As different colors melt at slightly different temperatures the glass "moves" as it melts. One color moving over another creates wavy lines and different colors. I've found that the kiln side is often more the one I prefer. If you want the shelf side of the piece to be the showing side do a flip and fire-polish, the lines will stay as you made them.

Thank you Doug-your advice works fine when the glass used is opalescent however when it's a clear/transparent mix, the wavy lines are visible from the viewing side. I've seen many artists that use a clear/transparent mix and have no wavy lines on what becomes the bottom of the piece but is initially fired up.

I have pieces going in today to be fused and Kevin has suggested a lower and slower approach-I fuse at 1550 so I'll lower that temp by 50 degrees and see what happens.

You might want to go down to 1400 and give it some time.

Doug Zawodny wrote:My 2 cents. The glass facing the shelf will stay the way you made it, It does what you tell it to do. The glass facing the inside of the kiln will do what it wants to. As different colors melt at slightly different temperatures the glass "moves" as it melts. One color moving over another creates wavy lines and different colors. I've found that the kiln side is often more the one I prefer. If you want the shelf side of the piece to be the showing side do a flip and fire-polish, the lines will stay as you made them.

To Doug's comment... if you keep within the same color intensity (and subsequently, similar viscosity) range with your color choices, you might find that even though the glass "moves" it moves similarly enough that the lines are straighter.

I also agree that you are firing WAAAY too hot for what you are trying to do. Most people who are firing at 1550 are depending upon the glass to move .

Dana W.