The CST sales website’s tutorial recommended using mylar, (mylar, *** is mylar) between the parting boards, part to be molded, and the epoxy tooling coat. After serveral weeks of searching internet for just what mylar is (just about any thin clear plastic sheet), I found out Aircraft Spruce had it by the roll 39” wide by as long as you wanted for about a $1.50 a linear foot. I bought 6 linear feet figuring that would give me at least four 1ft wide x 6ft long strips if needed. Finding mylar was a PITA!
I cut two pieces of mylar the same size as the two parting boards I was using cutting away the outline of the nose cone for main parting board and using the other full sheet on the bottom parting board.
I used 3M Drywall Cornerbead Spray Adhesive to attach the mylar to the parting board on The DB 60 mold, but misplaced it. The 3M 77 Spray adhesive I guess is the best but at better than $20 a can, at least at the one place I checked I decided to used whatever I could get my hands on, so I found an old can of Permatex Spray-a-Gasket Adhesive and it worked great. I fogged the one side of the parting board and one side of the mylar, waited a few minutes for it to dry and glued the mylar to the parting board.
If your just starting out like myself I would recommend the mylar sheet. I orginally was just going to wax the smooth side of the hardboard than spray PVA on it, but was talked out it by few members of RCU. Thanks
For those of you not in the know, as I was at first, epoxy does not stick to plastic(mylar) very well, if at all. Hence the extra protection as a parting surface.
First I attached the adhesive backed mylar to the adhesive sprayed base parting board. Next I drilled two holes through the base parting board for screws to attached the nose cone to the base parting board. Next I attched the mylar to the main parting board the same way as before and cutout the mylar from where the nose cone would be.