10 Year Old Deck, never been washed(help)

[ChrisK]

I have a deck to wash, it's 10 years old and has never been washed, or sealed. It is pressure treated lumber, with heavy mildew, and dirt. The people have 3 big dogs that keep the deck nasty. What do I use to clean it, what dwell times, nuetralizer(sp?) etc. Please help!!!!!!!!!!!!!!!!!!!!!!!!!

 

[Mike Hughes]

I dont care what anyone says about bleach on wood........I dont' see how you can clean this one without it. Heavy mold is not going to be cleaned with oxalic acid alone.

I would spray it with bleach, maybe half water, half bleach, power wash it, then brighten/neutralize with oxalic acid.

Anything you do to this deck is going to be an improvement!!

 

[Aplus]

I have had pressure treated decks that were under trees, in the shade, and growing tons of black, hardened mold, that have not been cleaned in many years.

My experience has been that no one chemical can truly handle these cases alone. Higher water pressure has been my best solution. It blasts the crustated mold off, reminding me of what it is like to scrape the bottom of a lawn mower....that crusty, green, flaky crud that builds up on the bottom. Once you get through this god-forsaken barrier, you can apply a nice oxalic bath, and brighten it up.

 

[johny]

I dont recommend bleach but if you dont have much expierence this would be the easiest way out.
The correct procedure would be industrial stripex mixed 1:3 and follow up with oxalic or citric acid,same thing as stripping,it would clean real easy.I cleaned this way 25 year old deck that had never been cleaned or stained,it was black,had moss growing all over it,it was redwood so.It turned back to red and removed everything,looked great,i know bleach wouldnt have done that and i was using just 500psi
Just my thought,
Johny

 

[Mike Hughes]

Johnny,

I have used strippers with success on old, nasty decks like this.........but always where there was a trace of thompsons or some other clear sealer from years past................never tried it on a deck that I knew had nothing on it but mold.........

I question how well a mild stripper would work on this one.........would love to do a test patch!

Mike

 

[rvagnoni]

Chris,

I have to agree with Mike. Your best bet would probably be the bleach solution. A stripper solution such as the one mentioned has sodium hydroxide in it and is overkill for such. This will most definitley burn the wood up and most likely cause it to fuzz. Even with nuetralizing. Go with the bleach mix first.

 

[ChrisK]

What would be a good bleach mixture????????
Also should I add liquid tide?? If so How much????

Thanks for all the suggestions guys. This board is great for us beginners.

 

[Jim Bilyeu]

Good Morning Gentlemen,

Myself, I have to agree with Johnny on this. The main purpose of using sodium hydroxide is to loosen this crud up to be able to remove it without doing damage to the wood. If this deck has never had any finish applied to it then the UV damage has already been done so the chances of getting the fuzzies is already extream, regardless of what cleaning process or cleaner you use.

I just bid a job for 1.6 million on a ski lodge in Eastern Oregon. This lodge has had nothing on it for 24 years and has a black crust from UV damage. They tried the bleach and everything else they could think of to remove this crust but nothing worked. I tested with Industrial Strip-X mixed 1 to 1 with about 45 minute dwell time, scrubed with a stiff bruse and re-applied more product. I gave the second application another 45 minutes dwell time and power washed it off. Did I get the fuzzies, sure did but I knew I would before I tested. The substrate was so degraded from UV I knew that no matter what I used, I would get the fuzzies. Did I get the job, won't know till next year.

I'm not sure what is meant by the stastement made above about this burning up the wood. I've never seen sodium hydroxide "burn wood before". Maybe some of your home made stuff might do this but I've never seen Industrial Strip-X burn wood. I have done several jobs where someone used bleach and burnt the wood and I contracted to go in and repair them.

Is sodium hydroxide over kill, some people might think so. Personally, I don't like doing rework and I want to give my clients the best job possible. If it takes over kill to do this, then so be it. I usally overkill all my jobs anyway.

Jim Bilyeu
Exterior Woodcare

 

[ChrisK]

So you are saying that I should use Sodium Hydroxide to clean this deck?
Will I need to neutralize the deck afterwards??
Where can I get the Sodium hydroxide?? (brands?)
How long dwell time???
Thanks guys

 

[Mike Hughes]

If you do decide to go with Sodium Hydroxide, you will have to neutralize it for sure. Every chemical company under the sun offers some sort of Sodium Hydroxide based stripper.

Neutralize with oxalic acid or citric acid. My favorite product for neutralizing is Ready Products #80 Brightner. It is all I use. It has oxalic acid, among other things in it. I would also brighten if you do the bleach route..............do it either way.

 

[reedsterstl]

I have had excellent results using the Wolman's "NEW" Deck and Fence brightner. It is a gel and blue in color. Excellent for pressure treated and you can turn the pressure up more than what you would dial into for cedar. Did a great job for me in removing mildew.