Unusual stain on deck

[Tunatussle]

Cleand cedar deck with Wolmans Deck Brightener, let sit about 5 days and sealed with F&P Cedar, two coats. That was beginning of May. May and June the deck was fine. Customer wet away at end of June and when she returned it had rained and the deck now has a white deposit that looks like a salt or ash where the rain would have hit. I tried to remove with mineral spirits, it did nothing. Try to scrape it off wiht the finger nail and that also does nothing to it. There is no construction in the area. I built new steps to deck they do not have the deposit. There is no deposit under the table and chairs where the rain would not have been able to jiot the deck. There is no deposit on the glass table top. I am not sure what this is or how to solve geting rid of it. Any ideas?

 

[Jim Bilyeu]

Hello,

If you look at the label of the Wolman Deck Brightner, I believe you'll find that the base ingredient is either oxalic or critic acid. What may have happened is that you mixed the product to strong or you did not rinse good enought. The crystals dried in the pores of the wood and when the water got on the deck, it reactivated the acid and it bleed through the finish and dried again. That is why you are only seeing it where the deck got wet.
When this happens, it will appear as a whith powder or crust.

If you apply water to the deck, these should disappear. However, as the deck dries out again they will more than likely re-appear.

Although this has never happened to me personaly, I have seen this happen quite often. The only sure way of solving this problem is to re-strip the deck and make sure that you rince it off completly. Depending on how much acid is left in the wood, this could be a chore. The acid will want to neutrialise the stripper on contact.

I've been reading allot of posts stating their mixture of this acid and was wondering how long it would take before someone had a problem with it. The most we ever use is one to one and a half pounds of acid to five gallons of water. This is more than enought to neutrialise a deck with. Anything over that is a wast of material and increases the possablities of having problems such as this.

Jim Bilyeu
Exterior Woodcare

 

[Target P/W]

Hey Jim,

A follow up.

I found Stripex at a building centre and applied it to a failing solid stain. It came off like hot butter/ no furring. 800 psi.
I think I have found a good product here. Always move to Stripex-L if I need the extra ummph.

Thanks again for all of your advice.

Chris.