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removing tannin stains on new deck

7 years ago

We built a pressure treated deck last summer. We kept a redwood picnic table on the deck, and noticed where the table was, black stains appearing on the deck. We moved the table to another side of the deck, and then the black stains stated appearing there. After doing a bit of research we learned that the nails in the picnic table reacted with the wood and caused the black stains, I think they are called tannin stains. I need to remove these stains before we can stain the deck. Will a wood brightener, such as Defy, work? I've read it is good for cedar and trex type materials, but nothing about use on pressure treated wood. As I understand it, it is the oxalic acid in the wood brighteners that remove the stains. Can anyone advise me on this? We removed the picnic table, but we still have the stains on the decking, I don't want to use a solid stain just to cover the stains, I want to remove them and then stain with a semi transparent stain. What is the best way to get rid of the stains? I've tried cleaning them with soap and water, it didn't do a thing. Help!

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