Mike Hilborn

These pictures are from decks that we cleaned and stained with Ready Seal from last year. The wood is cedar. We have dozens of decks like this that we are recleaning and staining for our customers in Minnesota. We have offices in Minneapolis/St. Paul, Milwaukee, Chicago, Madison, Fargo, Rochester MN and Eau Claire WI. Our largest office is in Minneapolis/St. Paul where we have had the most occurences of this problem. We just received our first call from a customer in Rochester that has the same problem. We have not seen the problem in North Dakota or Milwaukee. We have had very few of these in Chicago although there has been some. The most common response from our customers is that they never had this problem until we stained their deck. We have previous customers that have used us every 2 years for the past six years where it has just started. When I go to neighbors decks to the left and to the right I do not see the problem. Those decks have a stain that is a film. The commonality between each deck that has the stains is that it is made of cedar and that it is an oil based penetrating stain. One theory that I'm pursuing is that we were not neautralizing these decks effectively. In the past when we redid these decks, we would treat them with bleach but not neutralize them. The spots would come back within 4 to 6 months. At this time, we are heavily neutralizing them. We are also trying to find out exactly what the black spots are. We pulled a heavily infected board from one of our customers and cut it up into 4 pieces. We then cleaned 1 with bleach, 1 with hydroxide and 1 with percarbonate. We neutralized them all. We then shipped them to the University of Iowa. We are waiting for the results. If anyone has any ideas, I would like to hear them. Thank you.

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Thanks for the responses. The decks that we are having problems with are projects that were done the previous year. I should have the results back from the University of Iowa on Monday, June 24th. I'm sorry for the late response, I was out of town for a few days. I'll post the University of Iowa results soon. Thanks again.

We have been in contact with Ready Seal. Our Ready Seal representative Peirce Fitchett and Don (owner of Ready Seal) have said they would like to come up to Minnesota to see the problem in person. We have purchased a mildewcide additive at $400.00 per bottle from Sunbrite and are adding that to the decks that we are redoing. We are going to keep our eyes on those decks to see if the spots return. We have also been using an organic black mold killer called Moss Buster to also treat some of these decks. We will keep an eye on the decks where we have used Moss Buster to see if that makes a difference long term. Part of the problem with whatever this is is that you can't get it 100% out of the wood. There is still a residual stain left behind. We have used bleach, hydroxide and percarbonate to eliminate the black dots. At this time, Hydroxide does the best job at reducing the spots. Some spots go away others do not. We are watching to see if these stains will in fact fade with time or if they simply come back.