which is better

I have been looking at adtech epoxy surface coats for making epoxy mold for auto parts. At my job we only use PE tooling so this is new to me. I have been wondering if the es218 or the es221 would be better suited. I will be going with epoxy resin infusion for the process. I dont have access to an oven so post curing wont be happening other than if one day is hotter than the other lol.

Since Im just getting started I am looking at getting a small amount for now and I can get it by the quart locally thats why I was thinking adtech but am always open to suggestions.

Thanks