So I am placing an order that includes Duratec primer. I would rather not ship a gallon of catalyst and am wondering if the “Liquid Hardener” that you can get at an auto store (Napa in our case) works just as well. We have only worked with epoxies before and am less familiar with polyesters. It says “MEKP in Dimethyl Phthalate” which seems similar to HiPoint 90 from our composite supplier. Thoughts?
Should work fine but it would be easy to test a small amount first.
From what it sounds like the liquid hardener you mention is standard polyester catalyst, and should be just as good as the stuff you would like to order.
You could test the quality of the MEKP by pouring a bit into a test tube, and add the same amount of styrene. Now place your (gloved) thumb on the test tube, and give it a good shake. If it goes hazy, there is more than 10% water in it, and you could just as well toss it.
Of it stays clear, it either is low on water content, or they hid the water with salts.
Over here the liquid hardener is not readily available, so I am surprised at your place it is.
Do not use the BPO hardners, as they require a different catalyser (DMA instead of cobalt octoate)