Black spots on ipe

[CB works 14]

Has anyone else been experiencing these spots. One week after I started this job these spots showed up. it's now been 1 1/2 months since the job was complete and the spots haven't gotten any worse. These spots are not over the entire job, only over where the boards come to the end of the deck, where there are a few 2x4s that the ipe boards cross.

I had two other decks that did this that I completed over 6 months ago that are now covered with mildew. The thing with the decks that are covered in mildew is tthat hey had system under the boards to catch the water and divert it tio the edge to drain. I'm thinking that they hold a lot of moisture and that is where it's coming from. I'm going to go and see what I can do with them as soon as I slow down a bit (soon).

The process on the deck was:

8 oz per gal F-18,

let completely dry

8 ox per gal OX

sand with 60 grit

stain.

Should I be bleaching ipe after a process like that?

[plainpainter 217]

That's mildew baby....I have been stripping with Sodium hydroxide strippers followed by a oxalic bath - but noticed that sometimes the deck wasn't totally 'right'. Several times I explained it away - then I looked on my invoices and I write - strip/clean/ph-balance. Soooooo - I thought about - and decided that even if NaOH is good at killing mildew - it says so in some places, I only allow it to work through the old stain - and don't allow it to overly dwell into the wood - which I don't want anyways, since you will end up with furring. So what I have done is - cut down on my rinsing time - didn't overly rinse the stripper off - just enought to remove the old finish - and then I applied an oxi-clean/TSP over the entire surface and watched it do it's magic - it can also remove any remaining finish the NaOH stripper didn't - and really cleans up the wood well - you could try EFC-38. It actually lightened the wood as it dwelled - then I rinsed completely and the ox'd - and since then have had no more issues. The problem is - I can't downstream a percarb solution, and it is an extra step. I'd like to see what more seasoned pro's seem to think.

[Beth n Rod 1,279]

Try a plain percarbonate on it to kill the mildew. The Chemistry Store.com - Serving The Hobbyist, Student, School and Industry EFC-38 is also a light duty stripper, so I would not use that as a first course of action. I would start weaker and mix stronger. Neutralize as normal, touch up the finish as needed. If that doesn't do it, your mildew could be under the finish, in which case topical cleaning is moot. You could strip or sand the area, work on those spots and then re-apply the finish. I'll ask Rod to look at the photos as well and see if he has any other thoughts.

Beth

[plainpainter 217]

Beth, just curious - do you and Rod use a percarbonate cleaning step between stripping and neutralizing? Or do you consider the stripping agent alone as both stripping and cleaning? Or do you evaluate each deck for whether or not it needs an additional cleaning/percarb step?

[Beth n Rod 1,279]

Beth, just curious - do you and Rod use a percarbonate cleaning step between stripping and neutralizing? Or do you consider the stripping agent alone as both stripping and cleaning? Or do you evaluate each deck for whether or not it needs an additional cleaning/percarb step?

Depends on the job. At times we have to take the extra step, most times, it is not needed.

Beth

[Beth n Rod 1,279]

Has anyone else been experiencing these spots. One week after I started this job these spots showed up. it's now been 1 1/2 months since the job was complete and the spots haven't gotten any worse. These spots are not over the entire job, only over where the boards come to the end of the deck, where there are a few 2x4s that the ipe boards cross.

I had two other decks that did this that I completed over 6 months ago that are now covered with mildew. The thing with the decks that are covered in mildew is tthat hey had system under the boards to catch the water and divert it tio the edge to drain. I'm thinking that they hold a lot of moisture and that is where it's coming from. I'm going to go and see what I can do with them as soon as I slow down a bit (soon).

The process on the deck was:

8 oz per gal F-18,

let completely dry

8 ox per gal OX

sand with 60 grit

stain.

Should I be bleaching ipe after a process like that?

Sounds to me like a proximity problem with some of the coniferous trees or shrubbery dumping spores on the decks before you could finish them. Unless you are going to start misting the decking with a mildewcide before coating, this could pop up even after the regimen you followed.

Although the membrane installed under the deck can lead to moisture retention, there is no way that the mildew can grow completely through Ipe' in that amount of time if at all. It will eventually lead to failure of the installation with extended drying periods.

Rod!~

[carbbie 14]

What did you stain/seal it with?

[CB works 14]

Rod,

It could be because there are many trees that surround this house but check this out:

The first set of pictures are before and afters of a PT deck I did the week before I did the ipe.

Day 1 clean

Day 2 neutralize

Days 3, 4, and 5 dried to get the right moisture, and still wasn't quite where it needed to be.

Day 6 stain

The second set of pics are of the proximity of the ipe deck.

Day 1 clean,

Day 2 neutralize

Day 3 sand with 60 grit with hard pad, like I would a surf board.

Day 4 stain

It seems like that if I was going to have any problems, it would be on the PT deck. The deck has Live Oaks right above the black and green corner, with damn squirrels dropping their discarded acorns all over the deck while drying.

The after shot of the PT was 6 weeks after the job was complete and I don't see any problems.

I checked the ipe yesterday which is now into the fifth week. The dots haven't got any worse since I left, when I first noticed the problem. I've rubbed the dots with 12% and they don't disappear, I don't think it's penetrating the WT.

The major difference between the two decks is that I had to bleach the heck out of the PT to get it to look right.

Next time I'm going to treat the wood with 2% after I strip and see what happens.

Is there a mildewcide can go under WTW?

Carl,

I think I answered your question

Have you looked at your RS WTW ipe lately?

[Beth n Rod 1,279]

I checked the ipe yesterday which is now into the fifth week. The dots haven't got any worse since I left, when I first noticed the problem. I've rubbed the dots with 12% and they don't disappear, I don't think it's penetrating the WT.

Is there a mildewcide can go under WTW?

First, if the spots are under the stain, they are protected. Bleach cannot work on what it cannot react on...but if left unchecked, it will destroy the sealer.

Second, you can buy a mildewcide/fungicide additive in paint stores to add in. Check with the mfr first though.

Rod!~

[CB works 14]

First, if the spots are under the stain, they are protected. Bleach cannot work on what it cannot react on...but if left unchecked, it will destroy the sealer.

Second, you can buy a mildewcide/fungicide additive in paint stores to add in. Check with the mfr first though.

Rod!~

I thought you were talking about treating the wood with a mildewcide directly after stripping, neutralizing and sanding. Can a stain penetrate the wood as good with a treatment like that?

[Beth n Rod 1,279]

I thought you were talking about treating the wood with a mildewcide directly after stripping, neutralizing and sanding. Can a stain penetrate the wood as good with a treatment like that?

I was, then logic hit me and realized that most do not carry a license for pesticide applications so I opted for the additive.

Rod!~