#1 Deck Wood Brightener is a liquid concentrate that is mixed with water to brighten and restore the natural beauty of all species of exterior wood. This product excels at removing dirt, grime, rust stains, and tannin stains caused by fallen leaves. #1 Deck Wood Brightener is a safe, oxalic acid product that will not only will clean and brighten, but will neutralize the surface of the wood, creating an ideal surface that is ready to be stained. This product is step 2 of a 3 step system. #1 Deck Wood Brightener is intended for use on all types of weathered, exterior wood surfaces including decks, fences, siding, outdoor furniture, gazebos and playsets. Recommended for surface preparation prior to initial application of semi-transparent finishes and stains. Product can be used as a cleaner and brightener for redwood, or as a neutralizer to further brighten wood species, like pine, that have been cleaned with #1 Deck Wood Cleaner or stripped with #1 Deck Stain Stripper. For lasting protection of your exterior wood, after using #1 Deck Wood Brightener, treat the surface with #1 Deck Premium Wood Stain. Note: #1 Deck Wood Brightener is not formulated to remove intact paint, stain, or clear finishes and may dull painted and metal surfaces if not quickly rinsed. It is best applied with a pump-up garden type sprayer.