Mill-Pac Gray is an organically bound, non-toxic paste sealant that was originally developed for use in sealing foundry molds to floors or stools, or for sealing stress cracks or bad joints in molds. It has also found use in sealing boiler and oven doors, as well as sealing burners. Mill-Pac Gray will not handle any pressure, but its high temperature rating and low cost makes it a sealant of choice.
Mill-Pac Gray will stay soft until heat is applied. Once cured, it takes on a leathery-like consistency. Sealant is not an adhesive and must be held in place by the joint which is being sealed.