Can a water based deck sealer be used in a power washer? I am working on the underside of my second story deck. I will be power washing it then sealing it to try to discourage the Carpenter Bees that are drilling there little hearts out.
If you don't need to clean and reseal the deck to start with, you can use a wasp/hornet/flying insect killer in a spray can. They usually shoot a stream at least 10 feet so you can single out the holes and get the bees as they fall out. Fill the holes with caulk afterward so anything left inside can't get out.
If you plan to clean and reseal the deck anyway, a pressure washer does fine for cleaning but would have too much splatter and overspray for sealing. Try a roller on a pole or a garden sprayer with a long nozzle so you have better control applying the sealer.
A hand pump-up sprayer should work fine. We have even thinned paint and used one to paint a duck blind in the marsh. If it is water-based, you can even thin it slightly with water if necessary. For your application it should still discourage the carpenter bees.