I have been using the 635 resin/slow (#556) hardener for about 2 years. I also tried Raka, but went back to the USComposites stuff. If you'll read the description of the hardener it gives you a pot life of 35 to 40 minutes, set time 5 to 6 hours, and a drying time of 24 to 28 hours...at 80 degrees. They are not kidding. The Raka was much faster and worked just fine. However...I don't get in any hurry, so the USComposites stuff works great for me. Central Texas gets hot in the summer time. I've used this epoxy up to 100 degrees and above...though it does speed up considerably at those temperatures. You can use it a lower temperatures, but it takes longer. Still not a problem for me. I like to do a coat each day...though I do sometimes let several days go by. The hardener is blushless, and I've never had a problem with it at all. I've used the 6 oz E glass. It is fine...and came rolled, not folded. I don't know if that's the way they always send it, but that's the way I want it. So...everything has been fine. I'm going to order some more in the next month for a strip built and to finish a small S&G.