Fixing is a real witch.
First let the varnish has to dry 72 hours -maybe in your case give it a week in the sun to harden thoroughly, then wipe it down first with paint thinner(I am assuming it is oil based varnish so use odorless paint thinner on a clean rag and wipe down the surface.
. Now sand it . Personally, I have used varnish several thousand times (at least) and the onloy reason I use the varnish is to see the beautiful wood grain underneath like on fine furniture.
.Just saying...
. I am saying that because yours looks more like paint - not varnish.(or stained varnish)
. Personally I would sand it all off to the natural wood finish. using a belt sander because it is a flat board. Otherwise use 80 grit Garnet sandpaper(orange color) and hand sand like a mad monkey.
. Get it back to bare wood. Then up the grade of the sandpaper to 100grit and then to 120grit sheet. Then it is a chemical wash first with odorless paint thinner on a damp rag and wipe away the imaginary oil for it can be anywhere on the board. Let that air dry in the sun. Then get hot water and liquid dish soap and wash off the paint thinner. Let that dry for another day in the sun.
. Personally, I do not like the stain/varnish combination. If I was going to stain it darker I would get oil based stain in the color you want (which seems to be walnut color) Brush on the color and then use a cloth rag to wipe off most of the stain. This gets rid of the brush marks and allow the wood grain to show. Let this dry for a day in the shade and do not touch with your fingers while it was wet. Next day you brush on clear oil varnish. Leave that for a day. Sand the surface lightly with 180 grit to knock off the flies, or bits of snot...or miscellaneous stuff. You are trying to make the surface smooth which you felt with your hand. Once it feels smooth, dry dust (using another clean rag) clean it lightly and brush on a second coat of varnish. You will see the beauty of the wood. Let this dry for at least 2 days. And it is what you can be proud of.
(oh, if it is water based varnish, use a water based stain) Never mix the two and you will be fine.
What you have is a problem to fix. Basically easier just to sand it off and try again.
Or you can get paint and just paint it. But the oil is still there, so that is problematic. Maybe chuck the board and start on a new one.
http://i1173.photobucket.com/albums/r591/kam518/13B22297-8369-4BD3-9800-BBAF24BFB25A_zpsgwuo4goh.jpg
http://i1173.photobucket.com/albums/r591/kam518/E10F0A9C-5F88-4495-B6EE-0F34F0C9DA1B_zpswrdf4miu.jpg
I have used this varnish before on other wooden surfaces and it has not come out like this. Before applying i sanded the previous gloss (to a dull non-gloss appearance).
As i apply it just turns patchy. I have applied two coats already.
Any suggestions on a fix?
