Varnish problem

[carey mitchell]

For 30 years I have used plain old varnish for my projects. Most of the time I have mixed 1/2 semigloss and 1/2 satin to get the gloss level I prefer.

My last effort, however, went south. I had several quarts of gloss that I picked up at a bankruptcy sale for use on bamboo fly rods. I mixed it with 2/3 satin from Sherwin Williams. It settled out within hours, even though it was shaken well in the store only a couple of days before. I always filter using very fine mesh filters from the auto paint store; I had them shake it again and filtered it again. It settled again. I sprayed some and it clogged the filter in the sprayer. I am now convinced that it was not the silica settling, but the varnish itself coagulating.

I'm ready to spray another table and picked up a new quart from SW today. Now I have cold feet.

Has anyone had this happen?

[Jim Becker]

Was the gloss also SW varnish or some other brand? How old was it? Had it been previously opened or was it a new container?

[carey mitchell]

Was the gloss also SW varnish or some other brand? How old was it? Had it been previously opened or was it a new container?

Different brand, which has been on the shelf unopened for several years (ran across an operation that sells insurance claimed stuff; they had gotten an entire paint store inventory, from after a fire, most of the cans had rusty tops but I picked out 5 perfect quarts of gloss varnish for $2 per- I used it for dipping bamboo fly rods) Never had a problem with mixing this with different brands before.

[Prashun Patel]

Imho there are two possibilities:

Either the varnish is just old and has started to polymerize (my vote)

Or the 2 products you tried to mix are slightly incompatible. Formulations have changed over time as manufacturers have tried to comply with changing laws on volatile organic compounds. This can cause incompatibility.

[Jim Becker]

I'm with Prashun on this. And that last point is important..."varnish" as a term is a very generic thing and there are so many different formulas, it will make one's head spin, especially today with increased focus on VOC reduction, etc. A "best practice" with finishing products is to try and stick with one brand and even one product when mixing to avoid Mr Murphy getting a big fat grin...