The idea of epoxy penetration is a myth. It is essentially a surface treatment that may have some incidental penetration but certainly nothing like 1mm. The idea of hardening the wood simply won't work. What it does allow you is to get a superior bond between timber and timber, or timber and filler(where the filler itself is epoxy). A heavily oiled stock could be prepared for an epoxy treatment with acetone, or MEK (Methyl Ethyl Ketone), and you might get a good bond, but the timber may well be too contaminated to get a good bond. I certainly wouldn't do big areas.