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Mike Hilborn

Black Spots on Wood Decks

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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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Is there some kind of new mold strain floating around? I just posted a thread the other day about a similar situation. Ready Seal supposedly doesn't feed mold (more rhetoric) but the pollen that lands on top certainly does.

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Hmmmmm makes you wonder if adding additional mildewcide might be worth it...

Beth

That's why the Gray Away is made with extra mildewcide for us since Houston is so humid tropical.:cool:

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Speaking of.. still no samples Shane..

Sorry i was waiting on some clips with my stain order but the shipment is now due Mon-Tues.I'll get them out as soon it comes in.

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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.

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Tell me, how long between wash and seal?

Were there any pine trees in the vicinity?

Is someone draining a sprayer line and pointing toward the deck leaving caustic spray to land on it and go unchecked?

To me, it does not look like a neutralization issue but more of a fungus coming from inside the wood.

Curious to hear the results of your submission to the University of Iowa...

Rod!~

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Hey Mike,

If you recall, we participated in a meeting together in NJ last August.

That is some scary looking stuff. We also use Ready Seal almost exclusively here in NJ and also work on quite a bit of cedar. Have never seen anything like that discoloration to date. Sure hope we never do.

Two suggestions. First, the Forest Products Laboratory in Madison, Wisc. may be of some assistance. Their web site is: Forest Products Laboratory -- Forest Service -- USDA Everette Abrams may have a good contact there.

Also, the Western Red Cedar Lumber Association may be helpful. Their website is Siding, deck, deck design, fencing, gazebos, sheds & pergolas

If you get to the bottom of this, please let all of us know.

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Hey Diamond Jim,

Weird, you are only about 100 miles away as the bird flies and you are seeing this foul mold / fungus / whatever on jobs? Here in NJ in the past 6 years have never seen anything like it.

I'd be very surprised if it had anything to do with Ready Seal. Have you seen this on exterior wood stained with other products?

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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.

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Mike,

One other thought, though not original. Ready Seal "likes" a neutral to acidic wood prior to applying. Are the caustic strippers or cleaners without an acid app for neutralizing/brightening compromising the zinc?

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Is this thread pretty much in reference to same issues fenner been posting about?..If so it is getting abit rediculous that some know how to prevent, or get rid of and aint being forthcoming on the board here. I mean are you here to help people or what??!!

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Kevin, I have been dealing with the issue in the real world and not in theory. This mold evolve's from continUos wet conditions that do not dry out. Last year it rained 4 four months straight and in the fall. I have a job that I'll post that had a green film on the deck and roof. And the Ken Fenner black Spots. I have dealt with this mold over the years after rainy seasons and wet area's ( that do not dry out).

Every time I see the mold now. I tell the customer he has the ("Ken FENNER") Algeay-zar a terrorist mold......

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I guess you answered my question James cause maybe you felt some attachment to the issue I described of some not helping? If that makes for a side note fact than so be it...You alone are responsable for your actions or inaction. The topic of finding or offering solution for this mold problem has not much to do with theory..You either got it or you don't. Doesn't make a hoot of sense to describe the issue again to the forum without offering your supposed solution is what I am saying. If the stance your taking is that of not helping others on this, which would be in contrast of how you usually have been, then I truly feel sorry for you and wish you future health.

p.s.-

But hey to offer you a inspirational bone and to prevent bridge burning..Please go ahead...Go ahead and make our day. ..double, tripple dog dare ya.. ..you can do it..Is just a little 4 letter word called 'help' :)

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Thats some great Advice Rick

Hey Mike,

If you recall, we participated in a meeting together in NJ last August.

That is some scary looking stuff. We also use Ready Seal almost exclusively here in NJ and also work on quite a bit of cedar. Have never seen anything like that discoloration to date. Sure hope we never do.

Two suggestions. First, the Forest Products Laboratory in Madison, Wisc. may be of some assistance. Their web site is: Forest Products Laboratory -- Forest Service -- USDA Everette Abrams may have a good contact there.

Also, the Western Red Cedar Lumber Association may be helpful. Their website is Siding, deck, deck design, fencing, gazebos, sheds & pergolas

If you get to the bottom of this, please let all of us know.

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The solution was and is very strong bleach. The type of mold /algae is very aggressive and happens during very wet periods. The fungus can come from trees and get blown onto decks. To kill it you will fur up the surface of the deck. So be prepared to buff. If something isn't working go stronger !!

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