for a 'mirror' type finish, the technique that you would use would be called 'polished varnish'

in order to get a mirror finish you first need 5 to 6 layers of varnish with no drips or runs. rubbing out each layer with red scotch brite pad follorwed by light sanding with 220 grit paper (to deal with drips and runs) will allow you to build up the first 5 to 6 layers.

once you have the base, the final polishing begins...and after the final coat of varnish it is red  scotch brite pad, then 400, 600, 800, 1200 grit wet sanding.  then polish with grey, then white scotch pads then a final polishing run or two with a high quality carnuba wax boat or auto polish.

fwiw...this is a fairly time consuming....but impressive looking finish when executed properly.

i have executed it on one of my boats and it always gets wonderful remarks.  

hope that helps.

h

Wow!  Maybe a slightly less than mirror finish. It sounds that is all in the final sanding of the last layer.  The directions say to thin to 10% of the first coat.  Does that mean per amount? Example:  if I poured 6oz of varnish in a cup, do I then pour in an additional 0.60z of thinner to the mix?  I have heard to thin out the last coat.  Now I am confused.  Also what is the highest recommended paper grit to sand the epoxied kayak with to get the surface ready for the first coat of varnish, I've been told to work up to 600?  So far I wet sanded to 220.  I hope it's not too late.  I am starting to see a few spots that are showing traces of weave.