preparation of stainless steel casting rings

[Anthea]

hello there. i understood that a good kiln wash worked on stainless steel ... however i have just tried to dam glass chunks using a kiln washed steel ring lined with thin fire and the whole thing has stuck fast ... so first question is where did i go wrong (I fired to 850 C and annealed over three hours) and secondly how do i avoid this again and how do i remove the stuck glass Thank you!

[Mark Hall]

Had the same thing happen when using that thin flimsy kiln shelf paper. I used a hammer to make interesting pieces to refuse - getting it out of the ring. I've heard some folks say you might heat the works up & grab it with gloves, however I didn't mind learning the lesson by losing the piece. Now I always use the tried and true method of lining the ring with real fiber paper (fp) instead of shelf liner. I cut the fp strip to butt the ends, then place a 1/32" fp backup piece behind the seam for protection if/when it separates upon full fuse firing. I like round 'cookies' and don't like overlapping seams around the perimeter. Fresh kiln washed shelves provides the smoothest bottoms. I like to use fp in all available sizes; 1/32", 1/16", 1/8", and 1/4", for various tasks.

[Bert Weiss]

This is a simple compatibility issue. The steel shrinks more than the glass as they cool. It has a higher COE. The amount of shrinkage is compensated by compressing the fiber paper, allowing easy release. Kiln washing the steel is recommended, just in case the paper tears. So, yes you can heat the glass up to around 300ºF and it may well easily release. I never tried this with a ring, but it works with spherical shaped molds I use. In the case of the molds, I can't use fiber paper. If I take the glass out warm, it usually releases. But, if they both get cold, I have to invert and reheat. The glass falls out around 300.

Mark, I like to use the 1/32" fiber paper in as many layers as I deem necessary. They price it more or less by the pound, so this gives you the most options.

[Mark Hall]

It helps to establish a relationship with a local industrial supplier of refractory materials. I'm lucky to have such a supplier here that wholesales to foundries, crematoriums, and the like. They've taken a liking to struggling individual fusing artists like myself, and offer special pricing to their cut-offs, end of rolls, past use-by (dated) pails of fiber paste, etc. It's whats helped me become successful - my definition of successful is the fact I'm still able to focus on fused glass after 26 yrs. in business!

[Bert Weiss]

It helps to establish a relationship with a local industrial supplier of refractory materials. I'm lucky to have such a supplier here that wholesales to foundries, crematoriums, and the like. They've taken a liking to struggling individual fusing artists like myself, and offer special pricing to their cut-offs, end of rolls, past use-by (dated) pails of fiber paste, etc. It's whats helped me become successful - my definition of successful is the fact I'm still able to focus on fused glass after 26 yrs. in business!

Success!

[JestersBaubles]

ThinFire is not thick enough to provide the space you need, because the steel shrinks more than glass (as Bert said in his post).

Use 1/8 or thicker fiber paper. You can put a ring of ThinFire or Papyrus around the glass and then wrap in fiber paper to keep the edges a little smoother (since fiber paper will leave the edges "popcorn" like).

Dana W.

[Mark Hall]

Plus it helps to back the glass away from the walls when loading, so the molten glass oozes up against the fiber on it's own.