Ok, say you come across a dirty filthy deck that hasn't been treated in 5 years. You take the time to clean it back to bare wood and then stain it.
Now this deck is in full sun and alot of traffic.
Next year - the stain has worn off on the steps a bit and took a beating from the sun. But it isn't the monster to clean anymore - how do you deal with a 1 year or 2 year old finish? Just spread on some deck brightener and powerwash and add another coat? Or do pressure washers strip the deck every year with deck-stripper before applying a fresh coat of new deck stain?
-PlainPainter
No, you do not want to just put on some brightener. The deck must be properly cleaned of dirt and mold, and then brightened/ph balanced, or you will have problems.
And it is a bad idea to build layers of stain. If doing two coats of penetrating oil, it must be done "wet on wet". The first coat should not be allowed to dry before the second coat is applied. If you go over an already cured product with another coat, you are forming a film that will not penetrate and will peel.
Use a sodium percarbonate based cleaner and a pressure washer to remove dirt and mold. If the previous sealer was a penetrating oil, this should lift out pretty easily. If it was acrylic, all I can say is I'm sorry. I don't know why they even make that stuff. It peels after a few years, and is next to impossible to remove.
After the deck has been properly cleaned and thoroughly rinsed, use an oxalic acid based brightener. This will brighten it up like magic, and also ph balance the wood from the percarbonate treatment.
Then rinse, let dry, stain and enjoy!
Don't use any cleaner/brightener that contains bleach (sodium hypochlorite). This breaks down the lignin in the wood, and shortens it's life. Not to mention it is harsh on the environment.
I have started to add maintenance services for decks that I've built to my repertoire, and have studied up on the subject a little. I fully credit Ken from PressurePros for all my knowledge gained. He's been doing this for a while, and he knows his stuff. His Restore-A-Deck product that is a two part system that contains the chemicals described above. It is easy to use, and it works great. I've cleaned/sealed several decks with this stuff with very good success. (I'm not trying to spam, just relaying my experience.)