Sodium Percarbonate
Sodium percarbonate is a granular oxygen-based bleach that releases hydrogen peroxide and soda ash when dissolved in warm water. Unlike sodium hypochlorite, it contains no chlorine, has no strong off-gassing, and breaks down into water, oxygen, and soda ash after use. These properties make it the chemistry of choice for wood surfaces — cedar shake siding, wood decks, fences, and pergolas — where chlorine bleach would over-whiten the fibers and potentially damage the wood structure at higher concentrations.
In depth
In wood restoration, sodium percarbonate lifts gray oxidized lignin from the wood surface, removes tannin-based staining, and kills surface mold without the fiber degradation associated with chlorine. It works best dissolved in warm water at 4-8 oz per gallon, applied and allowed to dwell for 15-20 minutes before a gentle rinse. Most professionals follow with an oxalic-acid brightener to neutralize the alkalinity and restore the wood's natural color. On stone, brick, and masonry, percarbonate is also useful for removing organic staining where chlorine chemistry would cause reactions with mineral content.
How this shows up on our jobs
Sodium percarbonate is in every wood-restoration job we do — it's the chemistry that lifts the gray from a weathered cedar deck without cooking the fibers. We follow it with oxalic acid to brighten and neutralize.
Services where this matters
Related terms
Percarbonate
Sodium percarbonate is a solid granular compound that releases hydrogen peroxide and soda ash when dissolved in warm water — essentially an oxygen-based bleach. Unlike chlorine bleach, percarbonate does not contain chlorine, does not off-gas toxic fumes, and breaks down into water, oxygen, and soda ash after use. It is the primary chemistry behind most "wood-safe" deck, fence, and cedar-shake cleaners on the market.
Oxalic Acid
Oxalic acid is a naturally occurring organic acid (found in rhubarb, spinach, and many woods) that is widely used in exterior cleaning as a rust stain remover, wood brightener, and mineral deposit treatment. In exterior cleaning, its two main applications are: (1) brightening wood after percarbonate cleaning — oxalic acid neutralizes the alkaline residue and chemically reduces the gray tannin oxidation on wood fibers, restoring the honey-gold color of cedar and the clean appearance of pressure-treated pine; and (2) removing iron-based rust stains from concrete, masonry, and stone — the acid chelates iron ions, making them water-soluble and removable by rinsing.
Soft Wash
Soft washing is a low-pressure exterior cleaning method that uses biodegradable detergents and a controlled bleach solution to kill the algae, mold, mildew, and bacteria that cause staining — rather than scouring them off with brute force. A soft wash rig delivers cleaning fluid at roughly 60-200 PSI, comparable to a strong garden hose, which is safe on siding, shingles, painted surfaces, screens, and caulking. The chemistry does the work: the solution dwells on the surface, breaks down the organic growth at the cell level, and is then rinsed clean with fresh water.
Sodium Hypochlorite
Sodium hypochlorite (NaOCl) is the active ingredient in household bleach and the primary disinfectant used in professional soft washing. It is sold to exterior cleaners in 12.5% concentration (commonly called "SH" or "pool shock"), roughly twice the strength of consumer bleach. When applied in a properly mixed soft-wash solution, it kills algae, mold, mildew, lichen, and bacteria at the cellular level within minutes and breaks down into salt water and oxygen.
Tannin
Tannins are natural plant polyphenols — the same compounds that give red wine, tea, and oak bark their characteristic astringent flavor. In exterior cleaning, they are the source of the persistent brown, red, and orange streaking that runs down siding beneath overhanging trees (especially oak, maple, walnut, and cedar) and the rusty shadows that form under wood decks and pergolas. Acorn drip, leaf accumulation, and cedar-shake runoff are classic tannin sources.