Question for a urethane alchemist....

[oldguy668]

I bought a 4 quart kit of UPOL Raptor urethane bedliner. I used it on the underside of the fiberglass and much of the aluminum, mostly wheelwells. I also had to use some for a few non-FFR projects. The short story is that I made many small batches and I ended up with about 600 ml of material but no hardener. It's just enough to finish what I need it for, but useless without hardener. Since the instructions say to use any urethane reducer can I assume I can also use any 3:1 urethane hardener? I have plenty of Eastwood hardener, and I'd sure like to finish my work without spending for a quart of hardener I'll never use again.

[EZ$]

Based on my experience over the years, (been in the business 40 years), when you're using a hardener from one manufacturer, and a resin from another, the best way to confirm how they will work together is to measure the smallest amount you can, and still be accurate, and mix it to see how they react. Most times it will work, (set up), if you're using similar materials, but I've gotten some funky reactions as well. It will also be difficult to measure the properties of the cured material, and the manufacturers typically will be no help.
Rick