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Deck Cleaning Questions and Answers
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Topic starter
07/08/2014 2:49 pm
Hi - really need some help here. Can't figure out how to get rid of black spots on our ipe deck. The wood is 8 years old, originally stained with Behr deck stain which almost immediately started peeling and looked terrible. Stripped it about 2 years ago and I'm planning to re-stain with Penofin. However, stuck with these black spots. Started with Penofin step 2 cleaner since a stripper had already been applied. These spots have remained after a multiple applications of Penofin step 2 cleaner and step 3 brightener. I also applied a bleach cleaner to rule out mold (only to the shorter boards in the pic) after cleaning/brightening. They are slightly lighter but the black spots are still clearly visible. Penofin customer service has been helpful. They believed this was tannin staining from leaves or debris, but even a very strong application of some extra brighter they sent made no difference in the spots. So, called them again and they recommended step 1 stripper and possibly sanding. The spots go down into the radius of the boards, so I’m doubtful that sanding alone will resolve the issue completely. After applying the Penofin Step 1 stripper, the spots are still visible. What do you guys think is causing these spots and what would be the best way to remove? Thanks!
Topic starter
08/08/2014 1:33 pm
Yes, there is an overhang where the boards are clean. Since I applied more stripper to a test section (not shown in above pic) the other day and then posted the question, I believe the spots came from the original stripping process 2 years ago. I never applied any brightener after the Behr stripper. The Home Depot paint rep simply gave me the stripper and rented a power washer - all on them since the stain had failed so miserably - but never advised I must apply a brightener afterward to remove the dark color. Your reply further supports this theory. Now, I'm really concerned this might be permanent. Any thoughts? I am sitting here with a full container of Penofin Step 3 Brightener......mix it super strength maybe? Thanks
Topic starter
12/08/2014 10:40 pm
Used a very strong brightener mixture several times with no change in appearance. What do you think has caused this stain?.....not applying brightener immediately following the stripper from 2 years ago, or something else? It gets sun most of the day, so mold or fungus don’t seem likely (Behr rep says fungus), and the pattern is very consistent except under the overhang. Also, I hit it with bleach based cleaner in that small area without any change. To me, it looks like sanding or replacement of the decking. Although it seems very deep in the grain for sanding. As a test, I hit a small area with 80 grit on a palm sander with black still visible after almost 30 min. Can’t imagine sanding all 400 sf plus railing. Any ideas would be greatly appreciated. Thanks!
13/08/2014 11:23 am
Not sure what caused it but it is definitely in the wood and not on top of the wood. Sanding most likely will not remove it.
Only thing I can think of trying is a different brightener/acid to neutralize it out. Phosphoric acid is the best brightener we have seen for wood. Problem is that you cannot get it on aluminum or vinyl trim as it will etch the coating.
See if you can find some phosphoric acid out there somewhere and try that at about a 1 part acid to 4 parts water. Not sure where you can get it but I am sure some chemical store will sell it. Wear some gloves.
10/10/2024 3:38 am
@paulm were you able to find something that took that spotting out? I'm working on a deck with the same issue.
10/10/2024 3:39 am
@administrator I'm working on a deck with similar spotting. Nothing I have tried has worked. Any suggestions
This post was modified 6 months ago 2 times by keebo
10/10/2024 12:44 pm
@administrator I didn't reply directly but you'll see in the thread some pictures of the massaranduba after it's been cleaned and brightened. Also attached was some pictures of the before. The deck was never maintained after installation. The spotting that was dark is now much brighter than the rest of the wood, we think it was a fungus that ate through and as a result it brightened more than the original layer... if that makes sense
