It digs holes in the surface and furs the wood grain up damaging the siding.
Painting exterior siding without pressure washing first.
When pressure washing a lot of painters will get right up close to the surface to try to blast loose paint off.
It removes the dirt and broken down paint residues that keep fresh coats from adhering and gets rid of mildew that grows on paint in all but the most arid climates.
You always need a clean surface for paint to stick.
True most pressure washers are powerful enough to take off paint but for best results stripping should be a separate step done with a scraper sander or heat gun after the process of washing.
Hopefully this helps you cleaning walls before painting exterior of your home.
The point of pressure washing your house siding prior to painting is to wash it not to strip the paint.
If you try to paint over this chalky surface without power washing first the paint won t stick properly.
A thorough scrubbing is a must before painting any exterior surface.
Wood siding dries more slowly.
The cloth will likely come up dark gray with a layer of fine soot.
The same thing goes for dirt and dust.
When you schedule the painting job keep in mind that it may take your house two or three days to dry after you pressure wash it depending on the siding material.
Paint applied to dirty siding will adhere in the short term.
But over the years your house will experience paint failure faster than if it were applied to clean siding.
If you see grey spores or green growth on your home you may have a mildew or mold problem.
However most painting contractors like myself include pressure washing as part of entire exterior painting job.
As an experiment rub a clean white cloth across the unwashed siding.
They often succeed and then that 3000 psi water is blasting right into bare wood.
Prepare painting over old paint on wood to last before picking up a paint brush or roller few important steps to take in preparation when painting over aged paint on wood to last the longest.
If you still want your exterior walls cleaned before painting but do not want to pressure wash yourself you might call a local painting contractor.