Black Spots on Deck Boards

[tdig 14]

Hello,

I had # 1 clear kiln & dry pressure treated yellow pine decking boards installed last July with ring shank galvanized nails.

I have not been able to apply a stain/sealer yet (14 months later)

Now black spots are appearing on most of the boards.
It seems as if small cracks are developing and from those comes the black spots.

Tried Oxalic Acid based cleaner but made no difference - i don't think it is Iron Oxide Stains
I was going to apply a light semi transparent stain but now rethinking a darker maybe solid stain to hide the spots.
Any ideas what these spots are and if they will cause a problem after staining?
I have attached pictures.
Thanks for any help,

-Tim

[Adrian 155]

Sodium Hypochlorite, soap surfactant, and Dihydrogen Monoxide is what you need to wash it with. 49-49-2 mix

The Oxalic Acid is for neutralizing a prior stripper solution and brightening the wood afterwards.

 

Being that it is kiln dried wood, it's possible ( even kiln dried ) that the pressure treatment locked in some moisture.

That moisture is escaping now and creating what we in the south call shotgun mold, or Artillery Fungus.

 

Since you are not stripping ( unless I missed it ) then a good mix of what I mentioned above, possibly even some broom agitation should remove it.

 

..... and go with a semi trans oil based stain. Darker tones are like higher #'s with sunscreen lotion.

Darks offer more protection in the long run IF PREPPED CORRECTLY. and maintained afterwards.

[Beth n Rod 1,279]

Artillery fungus is different. But this is mildew, and it forms that kind of pattern.

I agree with Adrians suggestion. It should clean up easily.

 

Beth

[tdig 14]

Thank you both for your responses.

Is their an off-the-shelf product that containes Sodium Hypochlorite, soap surfactant, and Dihydrogen Monoxide with your suggested ratio?

[Adrian 155]

Yes, and it is probably already on your shelf at home.

Sodium Hypochlorite = Bleach

Surfactant= dish soap or the like.

Dihydrogen Monoxide comes out of your faucet.

The broom and bucket is probably in your pantry or closet.

 

Your Sodium Hypochlorite is  probably 6% in strength. So beef it up if you don't see instant results.

Contractors generally use 12% strength which is found at chem supply or pool supply.

Best of luck show some pics.

[Beth n Rod 1,279]

Bleach, TSP, Water, light wash, scrub, rinse, neutralize, rinse, let dry, prep, mask, seal, unmask. collect money. Done. NEXT!

 

Beth