I use Hot Line High Fire Shelf Primer and put on about 4 coats. I use an old ceramic kiln with settings 1-5 and high with a digital pyrometer. I use a very simple schedule. On "High" till the kiln reaches 930 degrees centigrade and then soak for an hour to let the most amount of glass flow through the pot. I do look to see how much has flowed and how big the melt is at that point, mainly because I've had the melt flow over the base shelf in the past. Obviously then I'd put too much glass in the pot. If the melt is in danger of overflowing, I vent the kiln by opening the door. If the melt is not big enough yet,I continue to soak until I assume the pot is empty. A quick way is to look to see if glass is still dripping through the hole to the shelf. Once the kiln has vented to about 550-520 centigrade, depending on the type of glass I'm using, I shut the door and allow it to cool naturally, usually about another 12 hours as it is a big kiln.
I use Diapads to remove as much of the shelf primer as possible, then cover the top surface with contact paper. I usually then put the melt in some almost spent acid, but you can also sandblast the bottom of the melt to get rid of any remaining primer.
Hope this helps.
Wash sticking to melt
I use Hot Line High Fire Shelf Primer and put on about 4 coats. I use an old ceramic kiln with settings 1-5 and high with a digital pyrometer. I use a very simple schedule. On "High" till the kiln reaches 930 degrees centigrade and then soak for an hour to let the most amount of glass flow through the pot. I do look to see how much has flowed and how big the melt is at that point, mainly because I've had the melt flow over the base shelf in the past. Obviously then I'd put too much glass in the pot. If the melt is in danger of overflowing, I vent the kiln by opening the door. If the melt is not big enough yet,I continue to soak until I assume the pot is empty. A quick way is to look to see if glass is still dripping through the hole to the shelf. Once the kiln has vented to about 550-520 centigrade, depending on the type of glass I'm using, I shut the door and allow it to cool naturally, usually about another 12 hours as it is a big kiln.
I use Diapads to remove as much of the shelf primer as possible, then cover the top surface with contact paper. I usually then put the melt in some almost spent acid, but you can also sandblast the bottom of the melt to get rid of any remaining primer.
Hope this helps.