Oh, its not 10 years old... *blows dust off the can* hahaha... I just followed the instructions on the can, but jeez, the first bit of it was nice and smooth, then it was all glumpy... I do drywall for a living, so Im used to mixing what's called "hot mud", its the powder that comes in a bag, you mix it with water, there are different "times" like 20 min, 45 min or 90 min mud... It hardens like a rock, hard as hell to sand, but great for base coat... ANNNNNYway, I thought this stuff would be the same, you just mix it and smooth it quick... I guess Im not quick enough, lol... I even thought about mixing up some hot mud and just doin it that way, lol... So just mix half the hardener?