Stir,stir,stir slowly until that  "gellattinous crap" is disolved, thats part of your varnish that has settled to the bottom of the can. I get paint strainers from the NAPA store to strain varnish they work great and are cheap.   

Yes, varnish should be stirred, but with new full cans it's tricky to do the job without spillage unless you take the time & trouble to have a second, clean container handy.

The idea is you first pour off 1/2 - 2/3's the un-stirred product into that clean container.

Serves two purposes: gives you room to work what's in the other can sufficiently to get that settled out goop back into suspension / solution (much of it is there to provide the build and UV absorption you've paid for) AND makes the procedure more effective by lowering the proportion of liquid vehicle to solids, until such time as you begin to add what you poured off.

Once you've gotten the goop back into shape and everything in one container, by all means use the cheescloth (or paper funnel + cheescloth 'windows') to filter it before use.

You'll be glad you did.

   I store paints and varnish cans upside down. Seems to make stirring much easier. Ditto on using strainers. 

   Thanks for the info guys! I thought I had been through the videos enough to be prepared for this step. I guess not.

   Thanks for reminding me that mine has been sitting for a long time.  I decided to get a head start on the stirring.  So far they have about 750 miles on them:

Hooper Williams - Brevard, NC