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Can I still use polyurethane that has thickened a little?

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Forum topic by BobVila posted 11-12-2017 08:38 PM 3636 views 0 times favorited 35 replies Add to Favorites Watch
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BobVila

16 posts in 9 days


11-12-2017 08:38 PM

It looks like my can of polyurethane has thickened a little, naturally over time I guess.

It isn’t coming out like Jell-O or anything like that, but it’s thickened just a bit to where I’m able to notice it.

Do you think it will be okay to use it, or do I run any risks of messing up the Finish?

I have the first coat on, so far it looks like any other first coat I’ve done with this type, clear Satin. So I haven’t noticed any huge differences, but thought I’d talk to you guys and see if anything jumped out in your minds when someone asks this question.


35 replies so far

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MrUnix

5905 posts in 2012 days


#1 posted 11-12-2017 08:52 PM

Is this oil based poly? If so, once it starts to kick, there is no stopping it – so use it while you still can! As for usability – absolutely! I have used it where I had to punch a hole in the top layer of poly with a screwdriver and then pour it out like honey into a mixing jar where it gets some added mineral spirits until it’s thin enough to wipe on. As long as it hasn’t turned into a rubbery jell, I’ve been able to use it. Just try to avoid the clumps :)

Cheers,
Brad

PS: The above is with using gloss poly… satin and others that have additives to alter the finish may not behave the same when thinned like I do. Although, you can get a satin finish using gloss only if you know how.

-- Brad in FL - In Dog I trust... everything else is questionable

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TheFridge

8137 posts in 1299 days


#2 posted 11-12-2017 09:11 PM

I have my suspicions that the OP isn’t really Bob Vila. Handyman extraordinaire… my boy Bob would know this.

-- Shooting down the walls of heartache. Bang bang. I am. The warrior.

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TungOil

709 posts in 308 days


#3 posted 11-12-2017 10:30 PM

I think I would approach this question from the viewpoint of ‘is the time and cost of materials I have invested in this project worth risking for a $15 can of finnish’?’

-- The optimist says "the glass is half full". The pessimist says "the glass is half empty". The engineer says "the glass is twice as big as it needs to be"

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Rich

1865 posts in 402 days


#4 posted 11-12-2017 10:43 PM

I’m with Tung on this. Maybe if I was putting a finish on something for the shop I’d use it, but for anything else, go with fresh. Also, investing a few bucks in a can of Bloxygen will help preserve your finish down the road. A $12 can will give several dozen treatments. You only need to use it for long term storage, not every time you close the can.

-- No matter how much you push the envelope, it'll still be stationery.

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BobVila

16 posts in 9 days


#5 posted 11-13-2017 05:55 AM

Well that sounds like good news for me seeing as how I asked the question after I put the first coat on.

And yeah, I agree, but in this case it turned out okay. I’ve got the second coat on now, looks the same as the clear satin always does, more woody.

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AlaskaGuy

3536 posts in 2122 days


#6 posted 11-13-2017 06:16 AM



I have my suspicions that the OP isn t really Bob Vila. Handyman extraordinaire… my boy Bob would know this.

- TheFridge

You forgot the part where Bob would sell his mother for buck.

-- Alaskan's for Global warming!

View Fred Hargis's profile

Fred Hargis

4711 posts in 2306 days


#7 posted 11-13-2017 11:48 AM

OP, when varnish cures 2 separate things are happening. The solvents that thin the solution are evaporating, and the compound itself is combining with oxygen to cure. Both start happening the moment a can is opened. Using your varnish is OK at this point, but like Brad said…use it all up quickly. You can still add some MS to thin it out but it would be wise to discard it after this project.

-- Our village hasn't lost it's idiot, he was elected to congress.

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BobVila

16 posts in 9 days


#8 posted 11-13-2017 01:36 PM

For those of you questioning if I’m really Bob Vila…...

View pontic's profile

pontic

478 posts in 421 days


#9 posted 11-13-2017 02:29 PM

You lucked out with the Satin. As fred says Urethane is an addition polymerization so once it is exposed to O2 the process starts and doesn’t really stop. This is why it becomes thick. Instead of brushing on microscopic ball bearings so to speak you are spreading on microscopic spaghetti. The spaghetti will still look smooth and shine alright but won’t spray on well and as far as the additives that make the satin satin or semigross they settleout of the mix and will need to be remixed before application. once the urethane thickens it will be much harder to evenly mix the additives. So You may get a different satin effect than you think.

-- Illigitimii non carburundum sum

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BobVila

16 posts in 9 days


#10 posted 11-13-2017 03:04 PM


You lucked out with the Satin. As fred says Urethane is an addition polymerization so once it is exposed to O2 the process starts and doesn t really stop. This is why it becomes thick. Instead of brushing on microscopic ball bearings so to speak you are spreading on microscopic spaghetti. The spaghetti will still look smooth and shine alright but won t spray on well and as far as the additives that make the satin satin or semigross they settleout of the mix and will need to be remixed before application. once the urethane thickens it will be much harder to evenly mix the additives. So You may get a different satin effect than you think.

- pontic

Yea, I wish I would have known. I was buying the little cans of it all the time, eventually I thought it was silly and went ahead and bought the larger, knowing I’d eventually use it all. Guess I was wrong.

View a1Jim's profile

a1Jim

116497 posts in 3390 days


#11 posted 11-13-2017 03:09 PM

Welcome to LJs
It seems a new can of finish would be safer to use instead of messing around with old finish, I’m a little puzzled why a simple chest proves he is Bob Vila ? I also wonder if “Bob Vila” the This old house host of days gone by would consider himself a “Handyman extraordinaire”?

-- http://artisticwoodstudio.com Custom furniture

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Rich

1865 posts in 402 days


#12 posted 11-13-2017 03:36 PM


Welcome to LJs
It seems a new can of finish would be safer to use instead of messing around with old finish, I m a little puzzled why a simple chest proves he is Bob Vila ? I also wonder if “Bob Vila” the This old house host of days gone by would consider himself a “Handyman extraordinaire”?

- a1Jim

I’m pretty sure the chest proves he’s not Bob Vila. Maybe if it had a banana leaf motif (very obscure reference to one of Bob’s most controversial shows).

-- No matter how much you push the envelope, it'll still be stationery.

View DS's profile

DS

2791 posts in 2233 days


#13 posted 11-13-2017 03:42 PM


I m pretty sure the chest proves he s not Bob Vila.
- Rich

That’s pretty much how I took it too.
I once worked with Danny DeVito and Bill Murray, but, neither of those guys were the famous ones.

For all we know, there are dozens of Robert Vila’s in the world. (Or would that be Roberto Vila?)

-- "Hard work is not defined by the difficulty of the task as much as a person's desire to perform it.", DS251

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a1Jim

116497 posts in 3390 days


#14 posted 11-13-2017 03:43 PM

Rich
I guess my point is ,is Bob Vila really that involved with or talented in woodworking,folks seem to forget he was just the host of this old house and not the talented tradesman, such as Norm or Tommy.

-- http://artisticwoodstudio.com Custom furniture

View DS's profile

DS

2791 posts in 2233 days


#15 posted 11-13-2017 04:04 PM

Bob, regardless if you are the famous Bob, or not, hopefully we all here can help each other improve and learn in our craft.
In that spirit, please allow me to make a couple of observations on your box that might help going forward.

  • There are mill marks from the planer in your top. Take some time to sand these out more thoroughly. There is also a burn or snipe mark on the edge of the top. Start with a slightly more aggressive sandpaper like 100 or 120 grit then progress through 150 to 180 grit. In an open-grain wood like oak or ash it isn’t typically necessary to go any higher with the grits. (Some might go to 220, but I usually reserve that for closed grained woods) Whichever way you go, use the same sanding treatment on all surfaces of the box to get a more uniform stain treatment on the entire project.
  • When staining, allow the full drying time before applying any clear finish over it. Open grain woods tend to bleed back in the grain as it dries and creates the darker patterns that are visible in your top. Once the stain has dried, it may make sense to wipe with a clean rag and some mineral spirits to remove the bleed out in the grain.

The rest of the box looks well made (what we can see of it.) Just don’t get impatient with the finish. Without exception, every time I rushed a finish to “just be done already”, it turned out poorly. I would be using ONLY the products I know will reliably do the job. If you think the old poly might be salvageable, experiment on a piece of scrap wood first before applying it to your project.

My 2 cents.
Welcome to Lumberjocks.

-- "Hard work is not defined by the difficulty of the task as much as a person's desire to perform it.", DS251

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