Great question. I have had the same question myself. It depends on how fast your epoxy sets up. There is a difference between wetting out time and getting the two different batches of epoxy to "knit" or bond together without leaving a line, bump or un wetted out line.

I believe that Nicks book says do one batch on one side, then the other side working your way down the kayak. I did this and never had a problem. I was worried about having multiple leading wet edges but this wasn't ever a problem.

If your still worried about it you can do what vaclav from one ocean kayaks does, Wet and scrape one side at a time. that way if you have any lines or problems they are directly on the keel. You wont notice them as much as if they run perp to the keel. (Based on my bad experience)

Good luck read everything you can BEFORE you epoxy and you will feel more confident, or very confused..

: I have read a lot of the responses as to how much epoxy one mixes when
: glassing their kayaks but I have not seen any comments on the sequence of
: application of these smaller batches. If you start with a 1/2 cup of epoxy
: and spread it out you have covered what amount of the surface and defined
: what perimeter of the wetted area?

: My question. If you started at one end and along one side of the keel you
: have 2 working edges that are hardening after the application of the first
: batch of epoxy, one across the keel and one towards the far end of the
: kayak. If you started in the middle of the kayak you have defined 3 edges.
: If you continue applying epoxy along one side of the kayak towards the
: rear what happens to the epoxy along the keel in the area of the first
: batch? Will it harden to a point you can not blend in the epoxy when you
: apply it to the other side of the kayak. I guess I am asking is there a
: difference between working time that applies to spreading epoxy and
: working time that allows you to establish a good knitting between
: different areas of application.

: What I envision along any edge that you have left stand for some period of
: time is either a feather edge or a bump of fiberglass that has hardened.
: If you drag out the epoxy along this edge to insure a smooth edge you
: would starve some of the glass along this edge, if you leave the edge with
: enough epoxy to insure saturation right up to the edge you would produce a
: bump along that edge.