Does anybody know of a non silicone based hi temp sealent (500 degree) to use on weldements to seal joints before sandblasting. We need to keep the S/B grit out of interier joints. The parts will then get powder coated. It has to be able to withstand the 400 degree of powder coat process. Also I was told that the powder coat process does not tolerate a  silicone based product. It would not have to hold anything just to seal the joint.  These are big products so it needs to be available in a regular caulk sized tube. Any information would be appreciated. Thank you.