Epoxy curing time thinner layers

When part A and part B are mixed, a chemical reaction occurs and creates heat. That is the heat created by the friction of the molecules that will induce the hardening of the resin (note that the ambient temperature will also accelerate the heat). The more important the mass, the more heat is created inside the mass. The more heat, the faster goes the cure of the resin. Consequently, when the layer is thicker, the resin will cure faster.