System 96 casting plates- getting rid of bubbles
Posted: Tue Feb 12, 2013 1:27 pm
hi there,
i am casting large open face molds with frit on the bottom and 3 layers of system 96 casting plates on top. the plates are 6"x12"x1/2" thick. i am getting mostly clean and clear results but in a few spots there will be a 1" bubble trying to breach the surface. this is not great.
my firing cycle is 10 hours to 1250F and a 3 hour soak at 1250F. then taking 2 hours to 1500F. the surface is smooth within 20 minutes at this point and i shut the kiln off and pull the plugs until about 1200F.
to get rid of these bigger bubbles i am thinking of trying a few things-
1- soak longer at 1250F or longer at a 1200F
2- break up the plates into smaller pieces on the top layer
i am guessing the bubbles are being trap in the center where the plates are stacked and the air has a longer way to travel to get to the edge. just a theory.
any ideas or suggestions would be greatly appreciated.
thanks, peter
i am casting large open face molds with frit on the bottom and 3 layers of system 96 casting plates on top. the plates are 6"x12"x1/2" thick. i am getting mostly clean and clear results but in a few spots there will be a 1" bubble trying to breach the surface. this is not great.
my firing cycle is 10 hours to 1250F and a 3 hour soak at 1250F. then taking 2 hours to 1500F. the surface is smooth within 20 minutes at this point and i shut the kiln off and pull the plugs until about 1200F.
to get rid of these bigger bubbles i am thinking of trying a few things-
1- soak longer at 1250F or longer at a 1200F
2- break up the plates into smaller pieces on the top layer
i am guessing the bubbles are being trap in the center where the plates are stacked and the air has a longer way to travel to get to the edge. just a theory.
any ideas or suggestions would be greatly appreciated.
thanks, peter