I've done several decks and what I do is similar to what you're thinking.First,I power wash the underside,maybe wire brush the worst spots,let dry and brush on a rust converter.Let that dry for a day then do another coat and let dry for another day.Over that,I brush on a heavy coat of rusty red primer and recoat with another coat after a day.Done.Simplicity paint is costly and worthless under a deck.Save it for the topside using the same as above process.I have a 50" deck on my Prestige. The deck is showing signs of age, but is in great working order. The underside has a lot of surface rust, almost no paint left, but there is very little deep pitting and absolutely no flaking. The top side has some paint chipping off in spots and as a result a little rust in those areas as well.
I would like to fix up the deck, but I certainly don't feel the need to restore it to brand new condition. My plan is to:
1. Sand the underside and other spots on the top with a Cup Wire Brush and a Radial Wire Brush attached to my drill.
2. Apply some kind of rust converter.
3. Spray on a primer coat.
4. Spray Simplicity orange.
Does this seem like a good plan?
Does anyone have any suggestions about what rust converter to use? Or, is it even a necessary step?
If I use the rust converter, is the primer necessary?
Any suggestions/tips would be appreciated.
Decks nearly always rust out from the underside from wet grass/dirt clinging to the suface dead air areas,usually close to the spindles.If you keep these areas clean and coated well the deck will never rust through.