Frozen lumber thawed, and now there's green on it

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Forum topic by scot2 posted 03-08-2012 05:44 PM 1489 views 0 times favorited 6 replies Add to Favorites Watch
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3 posts in 2807 days

03-08-2012 05:44 PM

Topic tags/keywords: frozen mildew mold green thaw

I picked up some “pressure-treated” 2×4s at a covered, outdoor lumber yard here in the midwest. Since the weather is cold the wood had some ice on it, I’m assuming based on the moisture from the wood.

After 24 hours of being indoors they began to thaw. I’m noticing now some green streaking along the grain. Could this be mildew?

I want to use the wood in contact with other wood, but I’m afraid it might be contagious so to speak. These pieces will be hidden, so the green color doesn’t necessarily bother me.


6 replies so far

View patron's profile


13658 posts in 3878 days

#1 posted 03-08-2012 05:55 PM

copper oxide is to keep mildew and fungus from rotting the wood

they don’t kiln dry PT
(notice how some is very heavy)

the streaking is the moisture and color mixing

not to worry
it does it’s job well

-- david - only thru kindness can this world be whole . If we don't succeed we run the risk of failure. Dan Quayle

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3 posts in 2807 days

#2 posted 03-08-2012 06:05 PM

Thanks for the quick response patron. Right, the label on the wood says Micronized Copper Azole.

Thanks again. I’ll wait a week to be sure it’s as dry as it can get, then proceed.

View treaterryan's profile


109 posts in 2824 days

#3 posted 03-08-2012 06:26 PM

Most pressure treated wood is either steam dried in the cylinder or kiln dried, especially for poles and dimensional lumber. On dimensional lumber, the Moisture Content is not to exceed 19%MC (This is straight out of the AWPA BOS) after treatment. The Copper in MCA can react with the resin in the wood and leave the blue-green color streaks along the grain that you are speaking of. These streaks fade fairly quickly with exposure to the elements. Sometimes, the streaks will ‘fade’ into a white granular substance – this can be removed with mineral spirits or just some simple light sanding.

-- Ryan - Bethel Park, PA

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109 posts in 2824 days

#4 posted 03-08-2012 06:45 PM

Another Note with MCA Lumber: Use Ceramic Coated or Stainless Steel Fasteners. It is less corrosive than other waterborne preservatives, but SS or CC fasteners are still required.

-- Ryan - Bethel Park, PA

View Bill White's profile

Bill White

5228 posts in 4497 days

#5 posted 03-08-2012 06:55 PM

And further more. Don’t get any of the sawdust inside your sweaty “T” shirt. Wahhhhh!

-- [email protected]

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3 posts in 2807 days

#6 posted 03-08-2012 08:50 PM

treaterryan, thanks for the additional info.

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