Hi Dechard,
Generally speaking it isn't a good idea to apply any car care product in the sun.
I just washed our black Pilot in the sun and have to move quick to wash it and dry it before water spots developed. We have horrible water around here, but it would have been much easier in the shade. (don't have any this time of year).
It also depends on what you mean by in the sun.
Do you mean in the morning, or late evening in the sun in November in Washington?
Or do you mean in the sun at 12:00 noon in August in Arizona?
Are you working on a white car? or a black car?
All of these things will effect how easy or how difficult a product is to use in the sun.
Your best results will come from working on a cool surface in the shade. If you have to work in the sun, then try to work smaller areas at one time. My experience with the NXT Spray Wax is that it's difficult to use on black Pilot in the sun around noonish here in SoCal. It might be easier if the Pilot was silver or white.
Mike