I have and use a 3500psi pressure washer for a lot of things including preparation for painting. Sometimes it works very well and other situations not so well. The problem is that you can damage the material under the old paint if you are not careful. I've found that on things like T1-11 it doesn't work well at all because the wood is too porous and soft. Actual condition of the paint is also a factor. don't know if this helps, but it is my experience.