stainless steel ring mold - separator advice

[Kitty]

i am finally putting together the glass for one of the SS rings i got from Matt Hoppes. i'll coat it with wash, but i want to confirm something else ... if i line the inside with fiber paper, should i use it pre-fired or unfired? i happen to have some previously fired from another project.

i recently made some pattern bars lined with unfired paper, and got some sharp spikes as the glass dragged downward as it condensed and solidified into the bars. in that case it didn't matter, because i sent the bars out to a tile shop to have them shaved and sliced. if i get spikes along the top edge of this circular casting, i'll have to cold-work them off myself by hand, which i'd like to avoid.

i presume using the fiber paper would be smart, since it would make it easier to release the glass after the thing is fired, right? or do you think just thorough coating of wash would be sufficient.

so, to line or not to line with fiber paper, and
to prefire or not to prefire the fiber paper?

TY - Kitty.

[Brock]

Line with unfired.

Count on edge work.

Brock

[Lisa Allen]

I agree with lining the ring with unfired paper, but you might also try to keep the glass in from the edges a quarter inch or so. So, it will melt out towards the ring instead of dragging down from being piled right at the paper. I've not tried it, but it might be worth a shot if you don't have a lot of coldworking equip.

Lisa

[Steve Immerman]

Agree with Brock and Lisa. Also, to cut the fiberpaper 1/8" thinner than you think that the finished piece will end up. ie, if you use enough glass so that you will end up with a 3/8" thick slab, cut a rim of fiber paper that stands on edge and is only 1/4" high. This should give you a fairly nice edge. Some coldwork may be necessary, but much less than if you use a wider piece (learned this trick from Doug Randall and it works).

Steve