Power Washing: The Prelude to Any Lasting Exterior Paint Application
The first and most important step in the exterior painting process is a thorough cleaning of the surfaces to be painted. Period.
Power washing is the logical and most economical way to remove surface dirt, but in the wrong hands, power washing can also create problems.
At Catchlight Painting, we follow these five steps to ensure the process is not just effective, but safe and non-destructive.
- Lower your pressure – use the lowest possible pressure to achieve your goal. Stripping stain from a hardwood deck will allow use of a much higher pressure than on a deck made of fir. Similarly, washing eaves and siding to remove dust, pollen, and evaporative salts (wet ground evaporates water and minerals – these are deposited on eaves and overhangs) likely requires a lower pressure than trying to remove years of mildew growth on a masonry surface.
- Tips – here is a good tip – use the widest fan at first, then move to a narrower fan as needed – the damage caused by a narrow fan, which increases pressure, can be immediate and lasting – we see lots of damaged cedar siding. I also recommend not using a pressure washer to physically remove paint – you’ll end up with paint chips everywhere but worse, exponentially increase the risk of damage to the substrate.
- Keep your distance – similarly, the logic of lower pressure and a wider fan applies equally well to keeping your distance from the surface as you clean -this limits potential damage and encourages appropriate use of a good quality cleaning solution to do much of the work for you – we actually refer to our power washing as a rinse – the house wash chemicals do the heavy lifting of emulsifying and loosening dirt, we simply make sure to thoroughly rinse the detergent. An important point to consider – protect adjacent surfaces, including glass, lights, copper gutters, etc. from cleaning agents as they can discolor and etch certain surfaces – we also wet all shrubbery and grass before we break out the detergent.
- But what if the paint is peeling or loose enough that washing is not an option? In this case, we prep first -scraping, sanding, priming to seal bare wood, then power wash afterwards.
- Properly performed, power washing adds significantly less water to the side of a house than hose washing, so we feel confident painting within a day or two of washing, assuming good drying conditions. There are exceptions to this rule – horizontal surfaces like decks, stained and aged siding which will allow more direct water contact with an absorbent substrate. Use a moisture meter if you have any concerns – these are cheap and available on Amazon and are an indispensable tool for any painter.
Final note – a power washer is a tool – effective in the right hands, destructive in the wrong hands. There are plenty of excellent videos on proper power washing on YouTube – favor those developed by the equipment and detergent manufacturers – then use them!
Meet the Expert:
Nigel Costolloe is the president of Catchlight Painting, a full-service residential and commercial painting company serving the Greater Boston Metropolitan Area. He is active regionally and nationally in the Painting and Decorating Contractors of America (PDCA) as a leader, speaker, and mentor.