gunk in my varnish

Hello fellow builders,

I've recently discovered a filmy gunk floating in the top of my schooner varnish and I am perplexed as to its origins.  I have not painted directly from the can and have been very careful to keep dust out of it.  I have noticed that excess varnish tends to coagulate around the inside edge of the can and I wonder if perhaps that explains the gunk?  I tried to extract it from the surface of the can wearing clean nitrile gloves but it was too slippery.  I tried mixing it in (probably a bad idea) and while the varnish looks clean, it now leaves little pieces of solid grit in my finish.  Anybody else run into this?  Should I just get a new can?



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RE: gunk in my varnish

   In any opened can of paint or varnish, after the first use, I always filtered what I was going to use into a clean new tray. I use leftover trays from the food store just large enough for my 3 or 4 inch foam roller.  There always is waste on the filter but with time and practice that can be minimized. I figured it was more economical than buying a whole new can. Dan

RE: gunk in my varnish

   what type of filter is recommended?  Would something like cheese cloth work?

RE: gunk in my varnish

   Actually a couple of thicknesses of cheesecloth should work dandy.  I've used a coffee filter for thinner finishes.  Check out the "StopLoss" bags CLC sells here.  they work great by allowing you to exclude all air, so no film.  it's the air that causes the film to form by oxidation.  A good experiment would be to get a nitrogen or argon gas cylinder from a welding shop and use a tube to displace the air in a part empty can just as you seal it back up.  But that's just me being geeky.  Get the bags, and filter your existing stuff before use.

RE: gunk in my varnish

I had exactly the same experience. Seems like the varnish reacts with air. To mitigate I a) carefully scooped out the film with a stir stick and poured it to a separate container, and b) left as short an interval as possible between coats.

Didn't see any blobs getting into the boat finish. 

RE: gunk in my varnish

   I bought the Stop loss bags this summer & so far they have worked great. I also have used the inexpensive paint filters I picked up at a hardware store. 


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