Clean the wall to remove dirt and sticky substances
Wipe the wall with a dry rag to remove any loose dirt before using a commercial or household cleaner. Also scrape off sticky substances from the wall by applying a little pressure on the rag. fingernails can also be used at the back of the rag to scratch the sticky substance ; however, do not scratch the wood directly.
Clean the wall and grooves with a soapy solution
Make a basic solution of dish washing detergent and water by mixing one tablespoon of the detergent in a large bowl of water. Take a rag and dip one of its corners in the soapy solution, wring out excess moisture and wipe briskly across any sticky substance on the wall and grooves, applying a little pressure as well if needed. Once the sticky substance has been removed completely, dip the other corner of the rag in clean water and thoroughly wipe the wall to remove any residue.
Washing soda, vinegar and lemon juice
If the dish washing detergent fails to remove the dirt and grime from the wall and grooves, try using vinegar, lemon juice and washing soda. Mix half cup of washing soda, ¼ cup of white vinegar and two tablespoons of lemon juice in 1 ½ gallon of warm water. Dip a sponge in the cleansing mixture and start cleaning the tongue and groove pine walls, using overlapping circular motions. Apply slight pressure to remove sticky substances and stains. You can also use a plastic scrub brush to remove any difficult stains; however, avoid scrubbing very hard, as it may damage the wood’s finishing. Dampen another sponge in clean water and wipe the walls and pine panelling to remove the cleaner residue.
Trisodium phosphate solution
For stubborn stains, use trisodium phosphate. It is a widely available chemical and can be easily found in any hardware store. Mix one tablespoon of the chemical in one gallon of lukewarm water and dampen a sponge with this mixture. Wring out excess mixture and gently rub the knotty pine and grooves with the sponge. Dip another kitchen sponge in the bowl containing plain water (warm) and rinse the wall and panelling to remove the cleaner.