I just wrote a letter to the company that distributed my driftwood I was so upset because I love the piece and no matter how much I scrubbed it and boiled it this stuff kept coming back, then I think it was Pixie that said she threw hers away because of it so I was even more upset..
So the company in question responded that it is perfectly normal but may take up to a month to disappear for the exact reason as liv2 described, it seems like it has taken ages to get better but it has and realistically it's only been 2 weeks but it looked so ugly and my fish wouldn't 'go near it until it got scrubbed and boiled....
The company said to keep soaking it in warm water, and if in 1 month it was still bad write to them again and they would take care of it for me..
I think one more boil and my piece will be perfect...
It seems like it takes forever but it wont.
My cories actually seem to like it but it soon grew back too much for them to handle so then I'd boil it again etc...
I think I have boiled it 4 times total..
HTH