Jay Another approach which has worked well for me is to thin a quart of varnish by 10%. Start your varnishing regimen from a regular unthinned quart of varnish. Upon concluding each coat of varnish , fill the quart container of unthinned varnish with thinned varnish from the thinned quart container. This technique maintains the proper viscosity throughout the application of 2 quarts of finish.

> After 5 boats, I finally learned to lay a decent coat of varnish.
> I've abandoned the foam brush for a badger. I pay strict attention
> to the viscosity of the varnish. A half a can of varnish will thicken
> quite a bit and need thinning for the varnish to lay out flat. (no
> brush marks) I used to stir in thinner slowly only to find that I
> would get an uneven gloss.

> (Caution-reading this may crash your computer) I now add a few
> cap fulls of thinner and shake the can vigorously for a several minutes.
> (I warned you) The next day, the bubbles have disapated and the viscosity
> is even throughout. I'm convinced that the uneven gloss was because
> the thinner was not thoroughly mixed.

> You almost have to memorize the viscosity of a new can of varnish
> and try to keep it that way. Now that the weather is getting hot,
> it starts to set up quick, even in the garage. I like to have it lay
> out flat in a few minutes. Anything more than that, and I may get
> into trouble with brush marks remaining.

> I now am using finer papers - like 300 grit (once it's level)
> I learned this from the people at Wind Song Canoes. I get a better
> final gloss with the smoother final sanding. As far as varnish, I
> use whatever is on sale. I've tried them all. It's what you do with
> them that makes the difference. For me, adjusting the viscosity and
> a thorough mixing of the thinner has made an enormous difference.
>