I need to wash a few years of accumulated dust, dirt and Mount Redoubt volcano off my flat, smooth wood siding. I plan to use my long extension pole (that I usually use for paint rollers and roof cleaning) screwed on to a soft brush.

Instead of dipping this brush into a bucket full of soapy water a thousand times, I wonder if I can instead use a hose-end sprayer to spray soapy water onto the siding.

Has anyone done this? Any particular sprayer recommended for use with soap?

Thanks!