At the present time I am in the process of building a plug of a kayak from which I want to cast a fibergglass mold. From this mold I intend to build my kayak. In the past I have had problems with the mold not separating well from my plug. I have made my plug from regular seaming compound because it is soft and easily sanded,however, after I have applied my parting compound to the plug I find that the resin which I use to make the mold of the plug eats its way through the parting compound into the plug and six months of work is ruined. I am looking for something to coat my plug which is made of seaming compound so that it will become a barrier to the effects of the resin and will prevent it from reacting with my plug. Has anyone out there got any idea what I can use as an effective barrier????? Thanks