Forum topic by Monte Milanuk | posted 07-24-2019 06:42 AM | 959 views | 0 times favorited | 11 replies | ![]() |
![]() |
07-24-2019 06:42 AM |
Topic tags/keywords: poly polyurethane expiration question finishing Recently moved and after getting the shop (mostly) put back together, started on some shop projects. Went to grab a can of polyurethane finish – one of several that had been collecting dust, rat-holed and forgotten, at the back of a cabinet at the old place. Not entirely sure how old it is – maybe 10 years? Definitely separated out so there’s a thick sludge at the bottom, that a stir stick isn’t going to handle any time soon. I do have a mixer/beater attachment for the cordless drill, assuming I can use it at a low enough speed to avoid sloshing or splattering the stuff all over. But I’m wondering… is it worth messing with this stuff – several individual 1-quart cans – or would I be better off to dispose of it and start anew? The cost isn’t really an issue. Thanks! |
11 replies so far
#1 posted 07-24-2019 07:26 AM |
10 year old poly? Trash it. IMHO – It’s just not worth the trouble to test fate and use old finishes on any hand built project that you care how it looks when done. Typically, If can has been opened the shelf life timer starts ticking. Most oxygen hardening varnishes or moisture curing poly finishes have a ~1 year shelf life after can is opened. If you amount left in can is less than half, then shelf life is usually less, maybe 3-6 months. After the finish shows thickening or sludge in can, attempts to use it can/will result in a poor finish. Could end up under cured and soft, or might have streaks in it when it dries. It’s not worth the trouble. I will admit that if I open a can, use some, and month later open again to find it has slight skin on top; I will scoop out the entire skin and toss it in trash. Then use what I need of clear liquid, while disposing of the rest not used in the next week or two; as it’s not going to last much longer. But if I open a can that looks cloudy or thick/sludgy, it’s toast. Based on reading of mfg literature: Unopened new cans are usually good for 2-3 years, sometimes longer if kept in cool place with reasonably consistent temperature and low humidity. Best Luck. -- If it wasn't for bad luck, I wouldn't have no luck at all, - Albert King - Born Under a Bad Sign released 1967 |
#2 posted 07-24-2019 09:41 AM |
I think this will sum it up for most folks. Is it worth the chance you are taking, because as soon as you slop some on, you can’t un-slop it. It certainly is a, “better test this on some scrap” before trying to ruin my newly made, and SANDED project. I often get more time in the final prep, as the entire project. -- Think safe, be safe |
#3 posted 07-24-2019 10:30 AM |
If the finish is oil based and unopened, it’s almost certainly still good. If it’s water borne, I wouldn’t chance it. Jewitt wrote an article a few years back and opined that solvent based finishes will keep indefinitely if not opened. His view on water borne finishes was that life was close to 2-3 years whether opened or not. IME, that’s pretty much the way things work. My varnish stash has several cans of unopened oil based varnish at least that old and I’m still using them…no problems whatsoever. I would guess the sludge (if this is a reduced sheen can, like semi gloss) is simply the flatteners separated out. On the other hand, I can understand the “why take a chance” aspect so tossing it isn’t that big a deal. -- Our village hasn't lost it's idiot, he was elected to congress. |
#4 posted 07-24-2019 04:03 PM |
i agree with all why chance it buy some fresh stuff,not worth screwing up a project. -- working with my hands is a joy,it gives me a sense of fulfillment,somthing so many seek and so few find.-SAM MALOOF. |
#5 posted 07-24-2019 11:50 PM |
In the trash with it or I have used old finish, not 10 years old, maybe 2 years, on a MDW work bench top. Got rid of the old stuff safely and sealed the top. Finishing is difficult enough without chancing bad results with old finish. -- Les B, Oregon |
#6 posted 07-25-2019 02:28 AM |
Well, sounds like I dodged a bullet on this one. I had ran down to the local Ace hardware store and gotten a small can just for this particular project, hoping that maybe I’d get the “all clear” to use the older stuff on some other projects. Guess I’ll pitch ‘em in the dumpster and start fresh. Thanks everyone! |
#7 posted 07-25-2019 01:18 PM |
Can you pitch them in the dumpster? Or do they have to be disposed of in a different way? |
#8 posted 07-25-2019 01:29 PM |
In most locations you cannot, waste pickup is almost always “solid” waste. You can let it dry, or pour it on something (I use sawdust for such things) like kitty litter it that oil soaker stuff, then throw that in the trash. If it’s an oxidizing oil (like BLO) you would want to let it harden on the absorbent before sealing it up in a trash bag. There is no reason to consider varnish as an oxidizing oil. -- Our village hasn't lost it's idiot, he was elected to congress. |
#9 posted 07-27-2019 12:01 AM |
For the sake of discussion, how long would it take an opened quart can of Helsman polyurethane to solidify to the point of being ‘acceptable’ for disposal? |
#10 posted 07-27-2019 01:17 AM |
IME – a very long time. Month or more, depending on amount and temperatures. My method of disposing of old finishes is simple: YMMV -- If it wasn't for bad luck, I wouldn't have no luck at all, - Albert King - Born Under a Bad Sign released 1967 |
#11 posted 07-27-2019 01:24 AM |
I’d pitch it. Imagine taking your brand new project and dumping maybe-maybe finish on it. Just not worth it. -- Most of my public projects: https://www.youtube.com/makethings |
Have your say...
You must be signed in to reply.
|
Forum | Topics |
---|---|
Woodworking Skill Share
|
13199 |
Woodturning
|
2814 |
Woodcarving
|
569 |
Scrollsawing
|
416 |
Joinery
|
1893 |
Finishing
|
6346 |
Designing Woodworking Projects
|
7906 |
Power Tools, Hardware and Accessories
|
32763 |
CNC Woodworking
|
330 |
Hand Tools
|
6453 |
Jigs & Fixtures
|
1804 |
Wood & Lumber
|
7277 |
Safety in the Woodworking Shop
|
1633 |
Focus on the Workspace
|
2633 |
Sweating for Bucks Through Woodworking
|
1272 |
Woodworking Trade & Swap
|
5417 |
LumberJocks.com Site Feedback
|
2396 |
Coffee Lounge
|
9659 |