Temperature is so important when doing these jobs. It really can't be stressed enough. Make sure you do the job within the recommended temperature. In fact keep the ingredients inside at room temperature before working on the project. The most important part is the initial firing off of the epoxy. Once it starts to go in the first hour you are usually good to go because it then generates it's own heat. I would have to read the recommendations for your particular epoxy but I wouldn't start in 60 degree weather unless that was within the limits listed on the can.

If you mess up and it doesn't go off then you have to start all over with an even bigger mess.

Mike Hill