: Ian-

: I have been told that the fill coat inside does not matter. I have not done a
: fill coat on the inside of my kayaks. If you want to do a fill coat you
: should probably wash the first coat down and light sand, in the past I
: have used a 3M green pad to do the scrubbing and then wiped the area down
: with a damp cloth.

: Tom

You don't want to sand into the weave of the glass. If you do this you will weaken its structural integrity. A very light scarring of the surface of the epoxy is sufficient to enhance the bond if you want to add another layer of epoxy. Apparently the epoxy will bond to the hardened layer just as well. Sanding is only supposed to offer more surface area for bonding. For a smoother surface, go ahead and do the fill coat but like Tom says, otherwise it isn't necessary.

Robert N Pruden