It is very important to wash your walls before you repaint if you want to achieve a professional and long lasting paint job. Your walls are covered with a thin, often invisible layer of grease and dirt from cooking, outside air, aerosols, crayons, candles, mildew and the like. This layer needs to be removed to make sure the new paint sticks to the surface.
TSP seems to be a staple of the painting process and the most frequently recommended cleaning product, but consider these facts before you go ahead and use it.
TSP stands for trisodium phosphate and usually comes as a white granular powder that you mix with warm water to wipe down walls prior to painting. You can also purchase it premixed. TSP prepares your walls in three ways:
TSP is a powerful cleaner that will remove dirt and grime. After application, rinse off all traces of TSP. The paint won’t adhere to places it is left on.
TSP helps remove stubborn grease spots, common in the kitchen, that prevent paint from adhering.
If you want to paint over a gloss or semi gloss paint, you need to dull the sheen of this surface first or the new paint won’t stick properly. An application of TSP solution will help break down the glossiness of the top coat.
NOW THE BAD NEWS!
IT DAMAGES THE ENVIRONMENT
TSP is an effective cleaner but it is also extremely damaging to the environment. Phosphates that find their way into our lakes, rivers and oceans have caused a shift in the balance of life by providing food for phosphate loving algae. These dense algae blooms have flourished and multiplied at the expense of other plant and animal life. Some areas have become dead zones where the water is so oxygen depleted that only bacteria and algae can survive.
Many phosphate products have now been banned in the US. Depending on where you live, using TSP may be against local, county or environmental regulations. Check before you let it run down the drain.
WATCH YOUR WATER FEATURES
If TSP gets into your pond or water feature, suffocating algae may bloom and ruin it for fish.
IT CAN BURN
TSP is highly alkaline and can burn unprotected eyes and skin. Wear suitable long sleeved clothing, eye goggles and rubber gloves to apply.
IT CAN KILL PLANTS
Plants don’t like TSP. Any plants or shrubs that are near where TSP is going to be used should be soaked with fresh water before application, and thoroughly rinsed immediately afterwards. This helps to protect the foliage.
IT CAN CORRODE
Metal, chrome and aluminum can be permanently pitted and stained by TSP. It may also etch the surface of some glazed tiles if left on too long. It can also attack and dissolve grout, making TSP a possible liability in your bathroom.
WHAT’S THE ALTERNATIVE?
If your walls are not too dirty, you can just use warm water, a sponge and some elbow grease. This will not leave any chemical residue. If you need a little more help, Simple Green is a water-based, non-toxic, biodegradable alternative.
If you are painting a glossy surface, scuff sand it first using a pole sander. Sweep the sander from side to side as you work your way from top to bottom. Remember to wear a dust mask and wash down the walls after sanding.