Founded in 1849 on the principles of quality and innovation, the Zinsser brand is known for professional-quality, problem-solving products that make the job easy and get it done right. Get ultimate hiding power indoors and out with Rust-Oleum Zinsser Cover-Stain Oil-Base Primer. This whole-house primer-sealer is a favorite with professionals. Use it to block stains, hide dark colours, prevent tannin bleed and penetrate and seal exterior wood.