REMOVAL OF IRON STAINS
Iron stains can be removed by scrubbing the stained area with an aqueous solution of oxalic acid in water. Dissolve 1kg oxalic acid to 6Lt of warm water. Scrub stained area using a stiff-bristle brush. Thoroughly rinse with water after treatment. When completely dry, lightly sand the surface. Surface must be clean and
completely dry (not just surface dry) before refinishing. Incomplete drying and retained subsurface moisture can cause finish adhesion failure.

Many of Construction Chemicals customers are involved with building renovation and in particular Oak frames, oak windows and beams as well as flooring. Our product range ensures that whenever timber is being used we have the products to bond, fill, preserve, sand, stain and paint. Our Customers will be aware of the problems of oak stains especially with green oak. This can look unsightly and spoil good looking beams or floors. OXALIC ACID CLEANS MOST STAINS FROM TIMBER.

REMOVAL OF BLACK WATER AND TANNIN STAIN
A common form of staining on wood surfaces results from contamination with iron. A portion of the extractives in wood includes a group of chemicals collectively called tannins. The amount of tannins depends on species; oak, redwood, and cedar are rich in tannins. Tannins react with iron to form a blue-black stain on wood. Common causes of iron stain include use of un-galvanized or poorly galvanized fasteners; OXALIC ACID brushed into the stains makes removal easy. Finishing wood with a WATER REPELLANT WITHA PRESERVATIVE AND/OR WOOD POLISH OR  OIL  greatly minimizes further iron stain and enhances the finish of the wood.. Wood must be clean; free of paint, waxes, oils and dirt. Use wood cleaners to remove any grease oils or grime. Use paint strippers to remove any finish, paint or coating.