[Greenbuilding] linseed oil finish causing freckles?

[Jefro]

I would highly recommend skipping the linseed oil altogether and going 
with pure tung oil.  If you thin it, thin with pure citrus solvent.  
Read here:

http://www.realmilkpaint.com/oil.html

Note that this is NOT "tung oil finish" from minwax or anyone else.  
Pure tung oil is a drying oil like linseed and can be flammable, 
although I don't think it spontaneously combusts the way linseed does, 
and it also dries faster than linseed.  It is thoroughly non-toxic (food 
grade when cured). 

Note:  since pure tung oil generally comes from either China or South 
America I'm not sure how "green" it is.