OxyClean or Sodium Percarbonate?

[GregDilley]

I had new western red cedar deck installed a few weeks ago. While we wait for the rain to stop for long enough to stain it, I've noticed some green coloration setting in some of the deeper grooved grain. I assume this is mold/mildew growing.

The deck is in a very shady, damp area.

I used OxiClean (4oz/gallon) with little success at breaking and eliminating the green stuff. I used a synthetic brush too and it stayed. The wood came very clean otherwise, but the green remained.

But then I wondered if the OxyClean is packed with fillers where its not as strong as straight up SP.

I've read so much on this forum (especially the old Bleach or no-bleach poll) about the success people have with SP. Am I using the wrong chemical/strength?

Thanks for your advice on this! This forum is great.

 

[Doug Black]

Sodium percarbonate is stronger yes, but the green coloring you are observing is very likely due to the pressure treatment and the newness of the wood.

 

[GregDilley]

Thanks for the reply. When you say pressure treatment...just to be clear, this is western red cedar. Untreated, unless i don't understand completely. I'll try to get a photo to post this evening.

Greg

 

[archie_MN]

4oz per gallon and brushing of Oxy Clean is strong enough. The green you're seeing is probably the start of fungi. Depending on how long that cedar was bundled as where it sat at the mill and in the lumberyard, sometimes "new" wood can be pretty contaminated before it's ever installed.

The professional treatment for this fungi would be a moss killing agent followed with a neutralizer.
The homeowner version is a jug of Clorox (6%) bleach watered way down (6-1ish) with a 15 minute dwell time. Rinse it thoroughly. I'd recommend neutralizing with an acid, your local big box store will have deck brightener with like 2% oxalic that should do the trick.

And yes, the very long bleach poll has mixed reviews. As far as I'm concerned, bleach on wood should only be used after cleaning when mold, mildew, or fungi are present. (not to start another debate)

 

[GregDilley]

Thanks again for the replies. I'm gonna try attaching my photos.

 

[archie_MN]

Looks like mold to me. The 2nd photo may be natural bleeding or just dirt. I might try a little sanding on that spot before bleach. I forgot to mention, if you're following my advice from above, thoroughly wet the area first. It opens the pores and gives better penetration for the bleach.

 

[GregDilley]

Thanks Jake.

So i'll try a little sanding on those spots...and spot treatment with the Bleach mixture you mention. I'll rinse thoroughly and then use a deck brightener.

Question 1: Considering the bleach solution will lighten the deck boards I spot treat, will the deck brightener even everything out again so some boards don't look much lighter than others?

Question 2: Do I need to wait any time between the bleach treatment and brightening?

thanks, I have a busy weekend ahead of me.
Greg

 

[archie_MN]

Answer 1: Use the bleach as needed and then brighten the whole deck. Any minor brightening from the bleach will be masked.

Answer 2: Heck no. Rinse the bleach and go for it.