We do deck refinishing in the Los Angeles area to keep your wood deck looking its best. This may involve pressure washing, stripping, acid washing and re-sealing. Sometimes sanding may be in order, replacing damaged boards or general repairs.
Most sealers break down under the UV light after a few years and are easily pressure washed off. Shady areas that haven't broken down may need to be stripped, which may darken the wood, as it is alkaline and the acid wash is used to brighten it back up.
After the washing stage, the deck needs a good day or so of drying before the sealer is applied.
Sometimes sanding is required to keep it looking it's best, as the wood can get very dark and needs sanding to lighten it up and to smooth out the boards, as they sometimes cup (warp up) on the ends. Sanding always produces the most uniform results, although it is a bit more expensive.