LumberJocks

Polyurethane turning into jelly?

  • Advertise with us

« back to Woodworking Skill Share forum

Forum topic by Barto posted 09-20-2009 08:12 AM 4233 views 0 times favorited 15 replies Add to Favorites Watch
View Barto's profile

Barto

24 posts in 2778 days


09-20-2009 08:12 AM

Hi,

I’ve got a 4 liter can of oil based polyurethane and it is turning into a gel like substance. Has anybody ever seen this happen before? Is it just plain to old? I’m absolutely sure I closed the can properly.

Thanks heaps. Don’t mind buying some more but still.

-- Bart, Waimauku NZ


15 replies so far

View scrappy's profile

scrappy

3506 posts in 2893 days


#1 posted 09-20-2009 08:30 AM

I’ve had some do that when it was in a clear jar. Put some in the jar to use for a job, (instead of handleing the large can) and after it sat for a few weeks with lid on tight, it had turned to gel. Really sick looking when it is still moveable but wont flow.haha

Not sure why, probably too old.

Scrappy

-- Scrap Wood's the best...the projects are smaller, and so is the mess!

View okwoodshop's profile

okwoodshop

448 posts in 2638 days


#2 posted 09-20-2009 09:03 AM

once the can is open and a little air gets to it, it gels after a few months or weeks depending on how much is left in the can. I have seen a product you can spray a gas in the can when closing it to remove the oxygen, never tried it so dont know how well it works.

View Barto's profile

Barto

24 posts in 2778 days


#3 posted 09-20-2009 09:32 AM

Thanks for your replies, but why does’nt (oil based) paint do this?

-- Bart, Waimauku NZ

View Scott Bryan's profile

Scott Bryan

27251 posts in 3285 days


#4 posted 09-20-2009 01:54 PM

Bart, polyurethane works by bonding with oxygen to produce a polymer. Whereas oil base paint deposits a layer of pigments as the “oil” evaporates. Once the poly is exposed to oxygen in the air it starts to polymerize and the process is irreversible.

You can minimize this to a certain extent by transferring the remainder, when the can is opened, to smaller containers (i.e. mason jars) with a minimal headspace in the container. Other options include putting objects such as marbles in the opened can to reduce the amount of the airspace in the opened can. Another product that was mentioned by OKwoodshop is Bloxygen. I have never used this but it is supposed to work by displacing the air in the can with argon gas.

Another solution would be to buy smaller containers of poly if you are not going to be going through a gallon any time soon. It is more expensive to do this but you will be wasting less of the product by having smaller amounts on hand. Another option, if you use wiping poly, is immediately dilute the concentrated poly to a wiping solution with mineral spirits (50:50) when the can is opened. I have kept solutions over a year without the poly gumming up.

-- Challenges are what make life interesting; overcoming them is what makes life meaningful- Joshua Marine

View patron's profile

patron

13535 posts in 2804 days


#5 posted 09-20-2009 02:04 PM

all of the above ,

or you can work more ,
and use it up faster !

-- david - only thru kindness can this world be whole . If we don't succeed we run the risk of failure. Dan Quayle

View Barto's profile

Barto

24 posts in 2778 days


#6 posted 09-21-2009 11:16 AM

Gentlemen, Thanks very much for the explanation. All makes sense, guess I’ll have to go for the smaller quantities. Hard for a Dutchman! Couple of dollars extra for a couple of liters (half a Gallon) more looks quite appealing!

-- Bart, Waimauku NZ

View patchy's profile

patchy

10 posts in 2982 days


#7 posted 10-07-2009 04:28 AM

Barto, it is probably too late now and evrything will have gelled over BUT, what I do is to place a spoonfull of baking powder in a small jar or jug and then pour a little white vinegar in. You will see the co2 forming by the bubbling action. When you think that the action has ceased you can test the gas by lighting a taper and inserting it into the jar/jug – the flame on the taper should go out. That tells you there is little or no oxygen left in the jar/jug.
Then simply tilt the jar/jug into the container of poly making sure that no liiquid flows in. The co2 will displace the oxygen above the poly or paint that you wish to save.
Those who have welding equip. can use a little argon or nitrogen for the same purpose.

patchy, British Columbia

View Barto's profile

Barto

24 posts in 2778 days


#8 posted 10-07-2009 08:29 PM

Hi patchy,

That is an excellent tip! I’m just about to buy another supply of Polyurethane and will certainly make use of your tip!

-- Bart, Waimauku NZ

View HokieMojo's profile

HokieMojo

2103 posts in 3191 days


#9 posted 10-07-2009 08:43 PM

patchy,
are you saying to “pour” the CO2 into the can of poly? Is the CO2 heavier than air that it can be poured? I thought CO2 and oxygen mix relatively easily and one wouldn’t settle out from the other. i’m intrigued by this, but i think I don’t understand it right.

View TopamaxSurvivor's profile

TopamaxSurvivor

17669 posts in 3139 days


#10 posted 10-08-2009 08:01 AM

The carbon atom in CO2 should make it heaver than O2. So in small quanities, CO2 should dispalce O2.

-- Bob in WW ~ "some old things are lovely, warm still with life ... of the forgotten men who made them." - D.H. Lawrence

View stefang's profile

stefang

15512 posts in 2797 days


#11 posted 10-10-2009 10:26 AM

Wow! You can learn so much on this site. The jelly problem has troubled me for many years and it’s so easy to solve with just a little baking soda and vinegar. Does it have to be white?

-- Mike, an American living in Norway.

View patchy's profile

patchy

10 posts in 2982 days


#12 posted 10-12-2009 12:12 AM

a) HokieMojo, yes, co2 IS heavier than air, when you say that co2 and o2 mix fairly easily don’t EVER go into a freshly painted confined space or partially confined space to find out!
b) Stefang, no, it does not have to be white, it just seems to be a cleaner solution (pun intended) – of,course you can always use ascetic acid.

Remember folks, this is a good way to keep ALL your canned/bottled paints/lacquers/ etc. in a useable form if you have containers with sufficient stuff left to make them worth keeping. All you are trying to do is keep oxygen from contacting the item in question.
patchy, British Columbia

View HokieMojo's profile

HokieMojo

2103 posts in 3191 days


#13 posted 10-12-2009 05:42 AM

thanks Topamax and Patchy. I didn’t know this. Very interesting.

View TopamaxSurvivor's profile

TopamaxSurvivor

17669 posts in 3139 days


#14 posted 10-12-2009 05:50 AM

You’re welcome :-)) Mike, it shouldn’t matter, acetic acid is in all vinegar.

-- Bob in WW ~ "some old things are lovely, warm still with life ... of the forgotten men who made them." - D.H. Lawrence

View TopamaxSurvivor's profile

TopamaxSurvivor

17669 posts in 3139 days


#15 posted 10-12-2009 05:54 AM

I was just thinking, always a dangerous thing:-)) A llttle shot form a small propane torch should displace the O2, its heavier than air.

-- Bob in WW ~ "some old things are lovely, warm still with life ... of the forgotten men who made them." - D.H. Lawrence

Have your say...

You must be signed in to reply.

DISCLAIMER: Any posts on LJ are posted by individuals acting in their own right and do not necessarily reflect the views of LJ. LJ will not be held liable for the actions of any user.

Latest Projects | Latest Blog Entries | Latest Forum Topics

HomeRefurbers.com