Hi,
Post cure in a black plastic bag!!?????????

I have some serious problems with attempting a postcure on an Epoxy that may or may not have been formulated for a post cure cycle. Most epoxy's made for general usage WEST, System 3, International, Ivory etc. etc. are not designed for post cure.
People like Ciba Geigy (?spelling) in Germany and various other manufacturers who supply Epoxy to the high end market. (Prepregs etc.) have developed thier products for use in ovens/Autoclaves. Here the temperature is critical and more important the slope of the increase of temperature as well as the dwell time and the cooling slope.
Most require 3min per deg C increase up to about 120 Deg c.

Now one of the problems of heating epoxy to much is that it breaks down and glasifies. The whole complex structure turns to mush.
SO! I would NOT repeat NOT try to post cure without full specifications from the manufacturer and a well made oven.

Rob

: I have been using Tightbond dark glue lately. The dark color looks nicer than the yellow glue.

: The white spots on fiberglass are due to movement of the glass in the epoxy (creep). If you post cure the epoxy to 130 degrees for a day and keep the boat out of the sun for a couple weeks, the problem is for the most part avoided.

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: The plastic transition temperature of epoxy is about 30 degrees above the curing temperature.
: Post curing raises the plastic transition temperature to 30 degrees above the post curing temperature.
: I post cure my boats in the sun wrapped in black plastic. (I think the October 1997 WoodenBoat has an article on a boat constructed using 2000 gallons of epoxy and it memtions postcure).

: Epoxy takes over 2 weeks to cure even with a good post cure. (I had a 3 foot long test section with a bulkhead at the large end. During the second week of cure the small end with no bulkhead increased in height by 1". The temperature was in the 80's.)
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