In a message dated 5/21/01 10:05:05 AM US Eastern Standard Time,
[log in to unmask] writes:

<< sufficient moisture to allow those
 acid vapors to form.  Some woods, such as oak (I'm not sure about teak) have
 the capacity to release such vapors, in the presence of moisture. >>

Paul is right about oak wood, which is probably one of the highest acidic
woods there is.
The Native American Indians would hollow out an oak stump or log, fill with
water, and tan hides in them. Hence the name, "Tannic Acid."

Scott
Florida