Some, perhaps most, wood-saturating epoxies (for example the BoteCote that I used on my Shearwater Baidarka) cannot be post-cured. The net result is that every time you take the temperature of the boat over 50 to 55 degrees Celsius (that's about 122 - 131 Fahrenheit), the epoxy will soften, you'll get differential thermal expansion between the wood, glass and epoxy and you'll get print through.

The solution appears to be "stay cool". Use light coloured wood, a boat cover, paint the boat white etc etc.

If you live in a hot climate, and want a dark boat, investigate epoxies suitable for post-curing. I have access to a room, big enough for a double kayak, which can be run to 55 degrees (131 Fahrenheit), but the elecricity cost for 24 hours runs to over $200! Try it at home and your floorboards and furniture will warp!

: Hi gang - My post of September 4 regarding the changes in epoxy/varnish
: finishes on my boats only brought one response. I emailed MAS Epoxies with
: the same question. Here is their verbatim reply: In a message dated
: 9/11/2000 2:13:49 PM Eastern Daylight Time, MASEPOXIES writes: > J: Yes
: pro builders have the same problem. What you are experiencing is a very
: well known phenomina of immaging or printrhrough. This means two thing,
: one you sevel of finsih and gloss are excelent, and two your boats are
: aging in a normal fashion and experiencing a slight degree of additional
: curing. With this slight additional cure comes a minute amount of shrink
: and thus immaging of the glass especially noticable on a dark very glossy
: finish. To reduce the immaging the boat needs to be thermally aged prior
: to final sanding and finish. How to do this is the tough part. Some folks
: heat (120-130) then cool the part a few times (thermal cycling) just like
: in real life. In simple terms the next time you sand and refinish the
: problem will likely dessapear for ever unless the boat is taken to a yet
: warmer environment (southern floridda and stored in a black bag). The pros
: tell the owners that their is always going to be some immaging and when
: they repaint the boat the problem will releave itself. Sorry I can't be of
: greater help.

: Thanks for your question Tony

: In spite of the typos, I thought the response was very informative. None of
: the books I've read on strip building mentions the effect, although it is
: apparently common. Is this effect only with MAS, or does West , System 3,
: Raka, etc. have the same problem? I wonder how I could "thermally
: age" the epoxy without exposing it to sunlight with no UV protection.

: I will still build! - John