Yes, I mixed it correctly.
I had to use 5 minute Devcon to do a repair to marble in someone else's home. At my home I use 20 minute, it sets rock hard overnight. I've spent days of my life using epoxy, so I know I mixed the correct amounts. Temperature is about 80 F.
But this 5 minute stuff is still a little soft a day later. I need to scrape the surface with a razor blade, but can't do it like this. Thanks.