Absolutely not. You should always protect the plenum (white diamond grid) on the vacuum former from direct heat of the kydex. Doing so will void your warranty and damage your vacuum former. This means you should always use the molding board, the DFD plate, or some other barrier to protect the plenum. When using the ThermaJig, you will not use the molding board or DFD under the ThermaJig, but you must make sure the hot kydex is not hanging off of the jig and touching the plenum board or damage may occur. If you must use an oversize piece of kydex in this situation for some reason, we recommend placing a cotton towel between the plenum board and the ThermaJig.