A method for making a polycrystalline diamond compact including the step of providing a polycrystalline diamond compact. The compact has a substrate of a hard metal composition of material and a volume of diamond material disposed on the substrate. The diamond material includes a mixture of diamond particles and a binder-catalyst. At least one pre-coating layer of organic material impermeable to a given acid or mixture of given acids is applied to at least an exterior surface of the substrate. At least one layer of primer material that is impermeable to a given acid or mixture of given acids is applied on the at least one pre-coating layer. A layer of top coating material that is impermeable to the given acid or mixture of given acids is applied to the at least one primer layer. When the given acid or mixture of given acids is applied to the compact to leach the binder-catalyst from the diamond material the at least one pre-coating layer, at least one primer layer and layer of top coating material protect the coated portions of the compact.