Hi Guys,
To tell ya the truth, I'd rent a vibrating-plate sander and sand the walking surface. 2 things are accomplished here:
1) No harsh strippers/cleaners used, AND
2) You get the best possible surface to stain anew.
3) Use a palm-sander for any spindles, etc.
* INCORRECT use of a pressure-washer can do more harm than good.
SIKKENS recommends sanding as the preferred method to prep a deck, if it's in the "rehab" category.
* Sanding gets rid of all the sun-damaged wood-fibers/dirt.
* When dust-free & ready to stain, the cellulose & hemi-cellulose (hard & soft wood graining) have an open, strong cell-structure to hold onto new stain evenly.
* If wood is only cleaned, you STILL have sun-degraded wood that's clean. It won't hold stain nearly as well, and tends to look blotchy.
3 yrs. ago I did this exact prep on our 10-yr old Redwood deck (west facing/no shade). Rented our stores' plate sander, 80-grit paper, and a sanding backer-pad.
* Applied 1 coat of Sikkens SRD Redwood color. We've got people coming from 300 miles away for the Sikkens products. However, we always stress it doesn't pay unless you do good prep!
* Deck still looks pretty good, but it needs a recoat every 2-3 years after cleaning of course!
* I don't care what some people think...NO deck coating is gonna last more than 3-4 yrs in full sun.
* The whole key is to STAY AHEAD OF THE DAMAGE. Stress this to your clients.
See ya,
Faron