POR-15 Self Etch Primer is a quick drying and easy-to-apply coating which enables a restorer to quickly topcoat POR-15 Rust Preventive Coating and other basecoats. You can even topcoat POR-15 that's been in place for months or years. This Self Etch Primer is NOT a high-build primer, it can be sprayed on almost any painted surface and can be top coated in 15 - 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.