Hi,
I am hoping to lay a 2msq section of Glasscast 10 over some old records on a floor. I need to have an edge on one side – what is the best way to form a barrier to stop the resin flowing out of the area I want to cover? I don’t necessarily want to create a mould for the whole area just the edge along one side – make sense?
What is the best product to form a barrier? I presume a piece of wood wouldn’t work?
Many thanks.

Can also just use a piece of wood covered with flashbreaker tape. Bit riskier than polypropylene, as any resin bleed under the tape and into the wood will bond the wood to your floor, so you need to be sure the tape is stuck down well. But with a clean piece of wood this is quite easy.

My personal preference would still be Warren's suggested method, but in case you were looking for a simpler/cheaper method.