Deck stained after rain

[Donald]

So I cleaned the deck with outdoor bleach, rinsed and waited for it to dry. Deck was very clean of any stains. Then sprayed "Wet and Forget" cleaner. It's suppose to clean and prevent future mold & mildew. Ammonia based. Sprayed and let it dry. No rinsing.

Deck is under a large oak tree

After one rain the deck has stains. While a couple of leaves ended up on the deck after the rain, it was not covered with leaves.

So what is causing these stains. They do not rinse off with a hose.

 

[Pablo]

Tannin from the oak. You can use oxalic acid or a tannin remover specifically designed for this.

Try a small area and get back with us.

 

[Donald]

Tannin from the oak. You can use oxalic acid or a tannin remover specifically designed for this.

Try a small area and get back with us.

But after every rain?

 

[shortyb]

But after every rain?

Yep. Warmer weather in summer brings the tannins closer to the surface. Eventually, they will fade away if your deck is stained/sealed well. Either clean each time or just let nature do it's thing. That, or cut down the source .

 

[Pablo]

But after every rain?

Oaks are mean like that.

What kind of oak?

 

[dkryan]

“Deck staining oak…..!”

 

[Donald]

Oaks are mean like that.

What kind of oak?

I assume your normal oak tree that drops lots of acorns. So white oak I assume.

 

[Donald]

From a friend who is a biologist.

I think the brown (tannic) stains are coming from rain drops off bark-- large branches. Those drops leach tannins from the grooved bark and also pick up small bits of dirt, insect bits, bird poop, etc. which would account for some of the tiny solids embedded in the stain drops. Probably unavoidable. Best to have a hose handy and regularly do a high energy flush.

 

[Pablo]

I assume your normal oak tree that drops lots of acorns. So white oak I assume.

Take a picture of the leaf. Acorns later. Your friend and maybe I could ID.

I would think some come from leaves, but not as much from bark/wood. You know the tannin in oak staves of barrels for fine wine.

 

[doitmyself]

Dang trees. Can't live with them, can't live without them. Have you hugged a tree today?