Black mold rapidly formed on Walnut-Bleach?

[Brad_bb]

So I hewed 11 pieces of walnut the last couple weeks.  It was very green.  The pieces got installed already on the outside of the barn.  Last couple days were very rainy and foggy.  3 of the pieces on the Northwest corner of the barn got some black mold on them.  This morning they were still wet I think from the fog and mist last night and it was 41 degrees overnight.  

I'm sure water with 2% bleach in a spray bottle would kill and make the mold disappear, but would it affect the color of the walnut?  Anyone ever tried it?  Maybe if I spray the bleach solution, let it kill, then rinse it?

Once these dry enough I'm sure it won't be a problem.  They are sheltered so rain will not get on them.  Pic taken before the mold issue.

[doc henderson]

I have used wood bleach, but to lighten stains.  I would try the bleach sol. on a scrap piece.  I am thinking there may be something like a vinegar solution that may work, and not discolor the wood.  It looks beautiful and sorry you are having this outcome.  can you put some fans on it to lesson the surface moisture.  are you worried about the look of the mold, or health risk (low)?  I think even dawn soap and a stiff bristle brush to remove the mold and let wood dry.

[scsmith42]

Brad, one option may be a fungicide.  Large volume hardwood producers will dry stack off the mill and then dip the stacks into a tank full of fungicide before sending to a kiln.  It keeps the wood from mold/mildewing.

If you go this route be careful not to get any of the raw product on you as it will burn.

http://www.iskbiocides.com/industrial/nexgen-wood-protectant-fungicide.php

[Nebraska]

Vinegar occasionally til it warms up enough the walnut dries enough to finish the surface with something mold doesn't like. Maybe a little borax  dissolved in water painted on.  Just a guess as I don't know if it will hurt the color nice job btw looks very good.

[Brad_bb]

It's February, 41, raining like crazy and fog.  Ground really has not frozen yet.  Strange winter.  Forecast is continuing temps in the 40's after this week- in February! It should be -5 to 32 this time of year.

The surface when I hewed it a week and a half ago was wet.  It sat in my barn for a week temps in the upper 20's lower 30's in IL.  Now installed in Indy, surface was ok until the mist and fog rolled in 2 days ago and wetted the surface.

I think I'm going to try the solution on some scrap.  Even if it doesn't discolor it immediately, maybe over time it might?  

I'm not sure if that fungicide Scott mentioned is available in small quantities, or if it's even available without a chemical license?  Anybody got some?

I'm first worried about looks, secondarily safety, but I know once dry it will not be an issue.  

[doc henderson]

if the bleach is aesthetically dis-pleasing, may have to wait until dry and brush it all off. it may make the wood darker and with spots from the mold.

[btulloh]

Maybe WetandForget would work and it's available widely at HD etc. it works well on siding and roofs. Don't think it hurts the color. 

I hate that kind of weather.  Sorry you're having a problem.  

[tacks Y]

I had white pine that sticker stained. Installed on my cathedral ceiling along with white pine timbers. Bleached it all after it was installed then sprayed CWF on it. Very happy with the results. 

[longtime lurker]

We use a stuff called Hylite NC or Hylite NCF as an antifungal. The company that make it are a division of Koppers. 
Whether you can get it there or not, and whether you'd need a license I don't know.

Other than that a bit of Copper sulphate dissolved in water and sprayed on will deal with it. There may be some surface discolouration from the copper but you can sand that out later once the wood has dried enough that it wont support fungal attack. Any veterinarian will have it - probably most pharmacies too. Vinegar will only kill whats there - it won't prevent another outbreak of fungal growth.

[btulloh]

I'm curious how copper fungicide from the garden center might work. Copper octanate is a typical active ingredient.  It must be pretty mild if it's intended for plants. 

[A-z farmer]

We buy cooper sulfate in fifty pound bags to use in cattle foot baths and for fungicide on crops.I would check with a farm supply store we get our from Winfield solutions delivered to us.We used to pay 15 a bag now it is around 50 .

[Brad_bb]

The one I bought from the garden center years ago was called Bordeaux.  I'm skeptical how walnut and the copper would react to each other.  Going to do a test of 1-2% bleach solution on a piece of scrap.  Even if it doesn't discolor, it may over a longer time or sun exposure.  I'll update in a few weeks or so.

[doc henderson]

The beams are beautiful.  of course mold left on the surface will cause stain as well, plan D might be to just physically brush the mold off until the wood dries enough to not support growth.  can you point some fans at the beam to dry the surface and keep it dry?

[GeneWengert-WoodDoc]

The black mold does not go,8nto the wood, as there is no food for the mold fungi inside the wood.  So, a light amount of black mold is really not an issue.  After drying, it can be brushed off with a stiff brush.  Any unwanted discoloration, if there is any, can be removed with wood bleach (oxalis acid). 

The mold does indicate very slow drying.  As soon as the surface is dry and the EMC is under 20%, growth will stop. 

[mredden]

I use 50/50 vinegar/water. Have not observed any staining on red oak or pecan,

Vinegar supposedly (according to the e-world) works better on black mold than bleach. It is reportedly better at killing the fungal "roots" in the wood.

I buy into the theory of vinegar being better because I can't stand the smell of bleach and I believe it's safer to work around. I buy lots of vinegar because I like to clean and de-rust with it. A gallon at wallyworld/sams/costco is pretty cheap too.