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I have fused several flat pieces in the past 2 weeks and every so often I get his white powdery color on the bottom side of the glass. My only guess is it is the kiln wash reacting with the glass? I am using the hotline kiln wash and all of my glass has been Bullsye or Uroboros, COE 90.

Has anyone else seen this and how can I correct it?

Thanks


Gabriel

Without seeing your pieces, my guess is that it is kiln wash stuck to the bottom of the glass, the chewing-gum-on-the-shoe of kiln work.

Possible removal methods:
Long soak and vigorous scrubbing.
Soak in vinegar and scrub.
Soak in household lime removers and scrub (which have been reported to change the color of some glasses).

Surefire removal method:
Sandblast.

Possible avoidance/minimization methods:
Fresh kilnwash after each full fuse firing, thoroughly dried.
Avoid opals next to shelf; use clear or translucent glass.
Fuse at the lowest temperature possible for your kiln.

Surefire avoidance method:
Fuse on fiber paper or Bullseye thin fire.

Jerry

Hi Gabriel,
Fusion Headquarters sells a product designed to take stuck kilnwash off the back of glass. I think it acts and smells like CLR - a product you can purchase at the grocery store or hardward store - its designed to remove calcium, lime, etc deposits from glassware, used to clearn out coffee makers, etc. Well anyway it works with some "elbow" grease. Another way would be to use the 3M diamond pads sold through the Bullseye Connection.

I like to fire directly on my kiln shelf but I am very careful not to refire on it if it previously went to a very high temp and that's where I am going again. I find that if I do a full fuse up into the 1500's on a fresh shelf and then follow that with a lower fuse in the low 1400 I have no problems. When I am in doubt about the quality of the shelf and don't want to rewash I use thinfire.

candy