I don't know if the epoxy you are causes blushing but if it does, wash the kayak with a mild soap solution. Then sand it lightly to scuff up the surface using fine sand paper, probably 120-grit will do, then apply your next coat(s) of epoxy...you will be fine. A kayak can be coated with epoxy any time any where. You need only sand the surface to help create a good mechanical bond between the old coat and the new one. Hope this helps.

Robert N Pruden

One additional thought - Tack cloths could contaminate the epoxy surface and interfere with bonding of the following coat.  Okay to use a tack cloth between coats of varnish or paint, but never between coats of resin. Jer

Arlene;

The normal maximum time between coats for a chemical bond for most epoxy brands is 72 hours.  After that it is better to rely on a mechanical bond by sanding before you put the next coat on.  Since you waited a week you could experince adhesion problems.  Worst case is that the last coat will start to peel away after some period of time.  You will start to see your finish become cloudy if this starts to happen.  Many feel that epoxy will still bind fine much longer then the 72 hour period; but the manufacturers are pretty specific.  So given where you are at, you could either take a chance and continue on or bite the bullit and sand the last coat off and reapply.  If you proceed and it turns bad, you will need to do a little more sanding to remove subsequent coats of epoxy and varnish; not really that much more work then it is to sand the last coat off right now. But you will have wasted more epoxy. Since you wiped down the previous coat with alcohol, you probably removed the blush if there was any.  Mas does not blush much if at all.  As someone else said you should not use tack cloths between epoxy coats, save those to use between varnish coats. 

I might be tempted to take a chance but then I don't always make the best choices:)

 Hope this helps; good luck with what ever you do.

Dennis