[Greenbuilding] linseed oil finish causing freckles?

[Chris Green]

Jim Meehan wrote:
> Thanks for all the replies on the linseed oil issue.  The light/dark 
> banding is not the issue -- I think that looks very nice actually.  Here's
> a closeup of the issue I'm talking about:
>
> http://vpizza.org/~jmeehan/gallery2/v/construction/20061118/IMG_1126.JPG.html
>
> It tends to be more prominent in the dark parts of the grain, but sometimes
> appears in the light parts as well.
>
> I'm fairly certain that it's not actually mildew.  These splotches appeared
> literally overnight, and the doors are dry to the touch, not damp or tacky
> like I'd expect would be necessary for mildew growth to occur.  Rather, I
> think it's a grain issue as some have suggested, or some interaction between
> the oil and the construction of the birch veneer.
Linseed oil cures by taking oxygen from whatever it is in contact with. 
I am guessing, but it looks like something might have been splattered on 
the veneer at some point. Perhaps you might get a cabinet scraper or 
single-edged razor blade and scrape down a few of those blotches in some 
unobtrusive place to see if you can remove them and how deep they are.
If the blotching is on both sides of the door, then it is the veneer 
which is probably at fault, a the condition originating in the veneer 
mill or en route to the door factory. If it's only on one side, then the 
splatter most like occurred after the door was assembled and before it 
was finished and installed.

You might also send your query and jpegs to the Forest Products 
Laboratory ( a USDA/ US Forestry operation since at least the 1930's) in 
Madison, Wisconsin  to see what they have to say about it..
Link to the FPL:.
http://www.fpl.fs.fed.us/

Chris Green.