REFLECTOR: pasty hardener

[Al Gietzen]

Andy wrote:

I have found that keeping the hardener in the warming cabinet shortens the

useful life

 

That was my experience also.  It darkened more rapidly, I guess due to
oxidation of the amines, or whatever.  The other factor is that the reaction
rate when mixed goes up exponentially with temperature, so it kicks off much
more rapidly at 95 F than at 75F which significantly reduces pot life.  At
95 F, if you don’t use what you mixed in about ½ hour it begins to thicken
and doesn’t wet out as well; whereas at 75F you might have 3 times as long.
Yes, at 75 you will get some crystallization after some months if you are
not using it; but a short term warmup to 110 or so and stirring gets it back
in shape.  Each time I added resin or hardener to the pump, I heated it
prior to pouring it in.  Kept things working well – never had to empty and
clean the pump.

 

I did on occasion put mixed epoxy in the freezer, and could warm it up and
use it a day or two later.  Also works for epoxy primers and acrylic paints.

 

FWIW,

 

Al

 

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