With the POR-15 Self Etch Primer spray can you can even topcoat POR-15 Rust Preventive Coating thats been in place for months or years. POR-15 Self Etch Primer is NOT a high-build primer like POR-15 High Build Primer but it can be sprayed on almost any painted surface and can be top coated in 20 - 30 minutes. It bonds incredibly well to POR-15 Rust Preventive Coating and all topcoats bond incredibly well to POR-15 Self Etch Primer. It can be sanded lightly and if desired multiple coats may be applied.