[JohnB]

All gelcoat is not the same viscosity, and use just enough duratech to make it flow out of the gun. I generally use about 15-25% duratech. If you used it 50/50, I am sure it would yellow pretty fast, and that is not what they recommend. You have to work fast with it, back down the catalyst a tad, and it's better if you use it around 70 degrees. The kick time on gelcoat varies greatly depending on temperature and exposure to sun. It took a while to figure it out, but I still think it's the best way to put gelcoat on a boat.