What's wrong with my teak?

[William Nimmo]

I went to an auction and got about 30 sheets of teak plywood at a price you would not believe so I wont post it. All marine grade , 3/4 , 1/2 and 1/4. Some of it is teak and holly.
Some is absolutely gorgeous and other pieces have some kind of dirt on it.
It is dusty and can vacuum a little off, and sand a little more off, and then wipe the rest with water or thinner, I think I can get it all the way clean, but it wont be easy. I am actually thinking of power washing it since the very fine black dust has worked its way into the grain.
I have about 10 pieces of 1/4 teak like this and was wondering what the heck. The wood was all stacked together so how could that get in there. Perhaps the teak's natural oil just attracted the dirt over the years in the lumber yard.
It almost seems as if the wood could be decomposing on itself, but is that really possible with marine grade ply stored indoors?
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[Dick Bringhurst]

It may be mildue (sp). Try a chlorx and water solution. Dick B.

[William Nimmo]

Bleach has no effect. It does not have any smell like mildew and it is on both sides of the wood Perhaps it is the opposite side of the material, which is not a teak veneer , breaking down and decomposing via some kind of mold. And then it spread to the piece underneath. I just hosed a piece and scrubbed and added bleach and not much help at all. When I wipe with a rag the rag is black in 1 pass, and the wood is still pretty dirty. If i clean and sand and clean again it is better , but not totally.

[William Nimmo]

I just pressure washed a piece and it got most of it off but wood still is stained.
The back cleaned off much easier than the teak side.
Anyone ever see teak veneered ply do this
I guess I will pressure wash it all and let it dry and just use it for furniture and cabinets backs.
What a shame cause the nice pieces just glow when finished.

[phil harold]

try oxalic acid to remove the stains