We’re trying (and we don’t mind experimenting) to create a piece from float that has a 3mm ‘indent’ but have yet to find the right combination of top temp/hold/glass thickness to eliminate the usual tell-tale relief on the top side - we’d like it flat.
The very useful Bullseye Tipsheet I found in t’archives
https://www.bullseyeglass.com/methods-ideas/tipsheet-1-kilncarving.htmlends at a stage 3 with a tantalising “ at 825/30mins the surface begins to level out...” suggesting higher temperature and/or longer hold and real flatness might be achieved.
Anyone done that? If it was in Bullseye, it would still give us a steer for float...
Chas