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 colors, prevent tannin bleed and penetrate and seal exterior wood.Excellent exterior wood sealerBlocks cedar and redwood bleedSeals water, smoke and nicotine stainsSticks to all surfaces without sanding