Steve:
I have been working with 30min slow cure epoxy but find my workable or useable application time to be quite a bit shorter. I have been mixing in a small 1oz medicine cup quantities of 1/2 oz max or less. I did not time it, but I must be getting less than 5 -10 minutes of application time before it gets too thick to spread. I have been applying with a cheap 1/2 brush like plumbers use for spreading flux, etc. The brushes were labeled "acid brush". I got them cheap like the mixing cups and I have no complaints about the epoxy not curing, but curing so fast, faster than I would expect.
John