Slow curing epoxy question ...

[John Burritt]

A refinement on Howard's cup marking is to calibrate the "master" cups by putting the desired amount of any liquid in one cup; set that cup in the "master" cup and mark the liquid level on the outside of the "master" cup.  This accomodates the level difference resulting from one cup inside the other.  Then all you have to do is remember to put a cup liner in the "master" cup the next time you're mixing epoxy.  Some of us have to relearn that occasionally.  Pouring into the cups definitely beats pumping if the resin is a bit stiff.

[Howard]

That isn't a refinement.....that is only the way to do it! 

(John explained it much better than I did)

[PAR]

I too stopped using pumps a long time ago, mostly because of the many different ratios I use. You can measure epoxy by weight too, but you have to contact the manufacture or more accurately the formulator for the ratios. Other wise you have to measure out, quite precisely, similar amounts and weigh them to establish the ratios.

I use the graduated mixing cup routine, though do have some weight formulas, like 7:3 and other odd ratios. Most of the common 3:1 or less ratio epoxies will tolerate a fair amount of resin/hardener miss-alignment. I've had batches kick being 10% off proper ratio, but would suggest it's pretty a compromised crosslink, so strength, flexibility, etc. can't be relied on for highly loaded pieces.

Higher ratio epoxies are less tolerant of resin/hardener errors. These more highly refined goos need the correct amount of materials or they don't perform well, if they kick off at all. This is especially true of the special "clear" resins, designed to use under varnish.

[trawler10]

Thanks, Gents for the input.  Yes, the "A" pump spurts and noted that the levels in the two jugs, A & B are slightly off as they should go down at the same rate, assuming the pumps working properly.  So, will make that adjustment, and to aid cure time will tent the halves and heat and that should take care of the problem.  Only noted it in areas that I was fairing so should have no, or only limited structural issues.  Bob