Poly Shelf Life

[Mt. Gomer]

Does Poly have a shelf life? If so, what is it and how can you tell if it's no longer good. I've got most of a gallon of Minwax Satin that's been sitting on my shelf for years (probably 5ish) as I bought it for a large project and have used other finishes on smaller projects since...

I'm guessing at the very least it's done a lot of settling and needs some serious stirring but is it even savable?

Thanks,

Travis

 

[mkepke]

If it hasn't skinned over or gelled up, I'd say it's ok. The easy way to tell though would be to finish a piece of scrap and see if it sets up as expected.

-Mark

 

[kooshball]

five years is a bit long for a polyurethane; if it is oil/solvent based it will stand a better chance of it being good vs a water based system.

If it is bad it will have risen in viscosity to the point of not being workable or have formed gels. Either way it probably won't apply as well as a fresh can.

 

[Mt. Gomer]

Thanks guys, I'll give it a try on a test piece and see what happens. When I popped the lid the other day I didn't see any sign of skimming over (it really was mostly full) so I guess I'll see what happens.

Thanks,

Travis

 

[ScottM]

My 2 cents toss it and start fresh. Why take the risk in ruining hours of work for $3.00 worth of finish.

 

[Larry Rose]

My 2 cents toss it and start fresh. Why take the risk in ruining hours of work for $3.00 worth of finish.

I'm with Scott. I used some that was old (2 yrs maybe) and it took the piece forever to stop being tacky. Compare to your time and sweat, poly is cheap. Toss it.

 

[Mt. Gomer]

Yeah.... that makes a lot of sense.....

 

[Gofor]

Back when I worked in mil paint business, the shelf life for oxidizing coatings (like enamel, varnish, etc) was 1 year, which could be extended for 1/2 that 2 more times, providing you took a sample from each batch, tested it by actually applying it, and then evaluating if it cured properly, etc. So basically, it was 2 years max.

Now that you have opened the can, and it has been exposed to air, you may want to use it, but I agree, it would be on shop cabinets, etc, not on a piece where it will really mess it up if it doesn't dry. Odds are that if it wasn't gelled or skinned over, it probably is okay, but it is a risk. You also may have a bit of a time getting the flatteners in a satin finish to recombine with the rest of it, and by stirring it all, you are going to introduce oxygen and start the catalyzing process in all of it.

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