What do I use on pressure treated wood

[Hobo]

New to this forum, but what great info., thanks to all.

I need to clean a pressure treated lumber deck but not sure what the best method would be.

Deck is 16' x 16', 10 years old, walking surface is 2" x 6" x 16 ft. pressure treated boards. Never been sealed, never been stained, still natural finished. It is dirty, has oil & grease spots from gas grill and eating area, has grayed and blackened in some areas, generally dirty, weather beaten and sun burned.

Deck is attached to house and finished with light gray aluminium siding.

All help on procedure, chemicals & comments welcomed.

 

[Craig Knight]

Hobo,

You just asked a mouthful, but here is what i do, and have been very successful.

1) I use a mixture that i have perfected by trial and error, for years. But, any sodium hydroxide based stripper will work. I treat all decks as they have some residue of past sealer/stain left on them. So soak with a sodium hydroxide based stipper/cleaner. Allow to dwell for 10 minutes or so, but do not allow to dry. Then using LOW pressure (500 to 1500 max) with a 40 tip, work each board, from one end to the other to prevent lap marks. If you make lap marks, your using TOO MUCH PRESSURE. Once you clean the whole deck with the stripper and LOW PRESSURE:

2) Rinse Rinse Rinse. Then:

3) Spray the deck with an oxalic acid mixture that will neutralize the wood and brighten the wood. Allow to dwell till nearly dry then:

3) Rinse Rinse Rinse.

The sodium hydroxide based stripper will assist in removing the grease stains, but if they have been on there for any length of time, let them know before hand, that there is a real good chance, that you can lift some of the stain, but not all of it.

I use a 40-08 tip to reduce pressure, then fine tune pressure from there with either a dual lance or from pressure washer.

Remember....LOW PRESSURE...LOW PRESSURE....LOW PRESSURE...


and did i mention...LOW PRESSURE