Eric Jacobson
09-11-2010, 10:25 AM
I learned something new since this thread (http://www.sawmillcreek.org/showthread.php?p=1351950#poststop) that answers part of the mystery.
While hand-planing a joined soft maple table top, I noticed the same familiar purple blotchy stains forming all over the maple. I called my brother, who is a woodworker, and he explained that the problem runs in our family and is, in fact, the acidity of our sweat reacting with steel tools and tannin in certain woods. I think most people have this problem to some extent. But apparently the sweat in my family is particularly susceptible to this phenomena. My brother complained that his sweat is so bad, there are certain woods he has to shellac first, in order to touch and work with, without causing stains.
My original pictures in this thread show two types of discolorations. I believe the second picture was caused by acidic sweat mixed with using steel turning tools and chucks and some unseasoned wood tannin.
If this is true, it explains a lot. I've been getting nasty stains on maple and oak every time I turn with them. If anybody has more info or can point me to some articles on said topic, please do. Google did not help. But I did read about tannin-reactive ebonizing, which sounds perfect for my blotched up bowls. http://www.sawmillcreek.org/images/icons/icon12.gif
While hand-planing a joined soft maple table top, I noticed the same familiar purple blotchy stains forming all over the maple. I called my brother, who is a woodworker, and he explained that the problem runs in our family and is, in fact, the acidity of our sweat reacting with steel tools and tannin in certain woods. I think most people have this problem to some extent. But apparently the sweat in my family is particularly susceptible to this phenomena. My brother complained that his sweat is so bad, there are certain woods he has to shellac first, in order to touch and work with, without causing stains.
My original pictures in this thread show two types of discolorations. I believe the second picture was caused by acidic sweat mixed with using steel turning tools and chucks and some unseasoned wood tannin.
If this is true, it explains a lot. I've been getting nasty stains on maple and oak every time I turn with them. If anybody has more info or can point me to some articles on said topic, please do. Google did not help. But I did read about tannin-reactive ebonizing, which sounds perfect for my blotched up bowls. http://www.sawmillcreek.org/images/icons/icon12.gif