I gave up on koa wool and satinite. It needs to be coated with ITC 100 ceramic which costs allot. I use castable refractory good to 3000 degrees. It takes longer to reach welding temps but holds them forever. Cost is around $65 total.
Kast-0-Lite 3000 is a good light weight, insolating castable refractory that is resistant to flux. If you are getting flux build up in the floor of your forge you are using to much flux. ITC-100 is terribly expensive and a better product, according to Mike Porter, and is much cheaper. I sell these products in small quantities so that you can buy only the amounts that you need.
I use a Ribbon Burner and a pyrometer and weld without any flux.
Wayne, just to clarify, do you mean that Kast-O-Lite is a better product and much cheaper than ITC 100?
("ITC-100 is terribly expensive and a better product, according to Mike Porter, and is much cheaper.")
(and thanks for all your help a few years ago when I was building my forge!)
Bill, the Kast-0-Lite is a better product than Satanite and Mike reports that Metrikote is better (and cheaper) than ITC-100.
I just re-read my post and must apologize for not checking to make sure that it made sense.
Wayne, is your KAST O LITE good to 3000 degrees? I would like the light weight idea. Mine is Mizzou 3000, pretty heavy but tough as concrete. I use flux at times so use a single burner and clay cat litter in the bottom.
Bruce it is the 3000 degree stuff. I think that you will be pleased with it. It is tough, light weight and insolating. You will find that it takes less time for your forge to come to temp. Also consider using Metrikote rather than the ITC-100. It is much cheaper and according to Mike Porter it does a better job for our applications. You might also want to look into using a Ribbon Burner. See the attachment at the Forge Supplies page of my web-site.