In a plastic or glass recipient, add 1 liter of lukewarm water and 75 to 100 grams of Oxalic Acid. Mix well with a wooden spoon. Do not use tools or recipients in metal.
Once the product is dissolved, with a paintbrush, apply generously on soiled wood. Wait 20 minutes and gently brush using a nylon brush. Repeat as needed. Once the wood as brightened, wash with clear water to neutralize the surface.
The brightening will increase slightly when drying. Neutralize good the surface to slow down the brightening process.
24 hours sheltered from sunlight.
CAUTION Poison and irritant. Wear protective glasses and gloves. Keep away from children.