I have read that CA is sometimes used for hardening soft spots that
can't be turned out for various reasons.

Has anyone used wood hardener, the sort used for penetrating rotting
wood to give it strength again. It's moisture activated, though with a
cure time of several hours over that of CA's seconds/minutes. Do the
chemicals used in such a product mean that its unsuitable ? The one big
advantage I can see over CA is price, so if time is not an issue it may
be a viable option

Thanks for any input
--
John