I don't foresee to much problem with using polyester for the endpour. While it may not bond well, even if the bond failed completely, I doubt it would go anywhere. And there won't be alot of stress working at breaking the bond.

Heat could be a problem. Wrap the end in wet towels or place it end first in a bucket of water.

> I will be ready to do my end pours in the next few days and since I'm all
> out of epoxy resin from the glassing, I am tempted to use polyester with
> microballoons for my end pour. What I'm interested in is any scientific
> reason why I should not use the cheaper polyester for this application
> since it is about 1/3 the cost. I am concerned with excessive heat during
> the cure (of course epoxy can do that also) and possible bonding issues
> between the poly and epoxy.