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Resealing Polyurethane Cans


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#1 norson

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Posted 14 April 2015 - 09:25 AM

Yes, this is an issue for me  . . . and it has been for quite some time. I really prefer using a high gloss polyurethane out of the can, rather than spray on, for many good reasons.

 

Yet, after use, even though I try my best to clean the rim and the lid, if the can sets on the shelf for awhile I often notice a "skim" or "skin" on the top when I reopen to use, indicating I am not getting a good seal.

 

Any suggestions on getting a good tight seal?

 

Thank you

-neb



#2 gdenby

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Posted 14 April 2015 - 01:28 PM

For tight can seals, I use a rubber mallet. But the "skin" may be inevitable. The oxygen present in the can when sealed will still crosslink with the urethanes. Probably would need to find some way to remove or replace the oxygen to stop the problem.


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#3 norson

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Posted 14 April 2015 - 04:40 PM

I've been using the same rubber mallet for years - and shudder when I see others using a claw hammer then a screw driver to open their paint cans.

8-)

I'm beginning to believe it might be dried polyurethane that is preventing a tight seal.



#4 rdemler

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Posted 15 April 2015 - 12:03 PM

Quite a few years ago we were using a product that had the same issue.After sealing the can a skin would form over the product.It was suggested that marbles be put in the can to offset the airspace in the can.It worked just fine,might work for your situation..Good luck!



#5 MJC4

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Posted 15 April 2015 - 01:13 PM

I quit buying the quart cans for this reason. I now use the pints.  Pint cans have less air space and less waste if they dry out.


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#6 norson

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Posted 15 April 2015 - 01:58 PM

But my paint brushes would not fit down inside the pint cans.

RATZ!

thanx

-neb



#7 Rad

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Posted 16 April 2015 - 06:15 PM

Gdenby may be right -- it might be inevitable. However, an old painters trick for getting the lip cleared of material is to poke a hole through the lip, from the top, on both sides with a small nail. When you replace the lid, the lid will cover and seal the holes -- this helps some. I personally have also transferred the contents to another smaller container that sealed tight when things got low in the can.
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#8 alador

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Posted 18 April 2015 - 11:15 PM

Long ago I worked with a commercial painter who had a couple of things he did for this problem. One was he would take a deep breath and blow into the can as he quickly put the lid on, he said that the moisture and co2 would help prevent that probleml. The other was he would pour just a thin layer of thinner on top of the contents of the can to prevent it from combining with the o2 in the can. I did at one time do a few jobs where I had several rooms at a time to paint and moving back and forth double coating with several roller and pans, sometimes I wouldn't get back until the next day. I started, instead of cleaning all the rollers and pans, I would put each into a small trash bag, blow it up like a balloon and tie the end. This worked very well, the paint would stay fresh in the pan for a couple of days if needed. Never tried it with polyurethane but the principle may hold.


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#9 Rad

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Posted 21 April 2015 - 12:39 PM

Picked this up on ehow --
Instructions
1
Open the can carefully with a can opener or a tool which will not distort the can rim or lid.

2
Clean all excess finish out of the lid and rim before replacing the lid to ensure no air will enter the can as a result of dried, hardened finish.

3
Press the lid into place on top of the can. Cover the lid with a clean paint rag to prevent spatters and close it completely by tapping it with a rubber mallet.

4
Place the can upside down on the storage shelf. Inverting the can prevents air seepage and traps air and varnish fumes in the completely sealed head space which is now above the varnish in the upside-down can.

5
Add just enough paint thinner to the can of polyurethane varnish to completely cover the surface of the varnish. Do not stir the paint thinner into the polyurethane. Let the paint thinner float on top. Use this method if the can lid is completely intact, or if you are uncomfortable with the idea of storing the can of polyurethane inverted.

6
Store the polyurethane varnish in a cool location. High temperatures increase the vapor pressure within the can which will lead to air seepage.

7
Store a small amount of leftover polyurethane in baby food jars or resealable glass jars with well-sealing lids. Match the size of an empty, clean glass jar to the amount of polyurethane left at the end of a project. Pour the remaining polyurethane into the jar, wipe the lid to remove any spatters or drips and seal the jar.
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#10 norson

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Posted 15 June 2015 - 10:33 PM

I found THE answer on my own. My wife washed out an empty PLASTIC mayo jar - with lid - and I poured the remaining polyurethane from that quart can that refused to give a good seal - - - six weeks ago and cranked the lid on tight.

 

It's PERFECT! I can use either size brush plus I can now stick the cane handle down into the liquid for a super heavy coat.

 

Did that this morning with the Sweet Gum cane I'm working on....pics to follow when it's finished.


Edited by norson, 16 June 2015 - 09:22 AM.





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