Well, last week this time, I had cast the fire chamber of my new natural gas forge. My plan deviated substantially from many of the published designs in that the fire chamber was designed to be a "floating" vessel. Unlike the insulated steel pipe types, this one is a thick cast refractory tube bedded in dry sand and encased with a rolled steel housing. I used a mixture of "Parker High Temp Furnace Refractory" (3000º max) and volcanic perlite and cast it between two "Quik-Tubes" (spiral cardboard cylindrical forms). I waited one week for it to cure, but it did little more than skin over. So, today I fired the chamber. I set a rosebud O/A torch directly down the center of it and blocked the other end with a steel plate to trap the heat. The inner tube burned away completely, but after 6 straight hours the outter tube hadn't even smoked! The refractory was fired hard though and now has the consistancy of comman brick mortar. The next step is to drill the holes for the burner sleeves. I'll keep you all informed. Ray Maiara Aurora Forge Staten Island, NY swage@spacelab.net