Replies

1. 
   kreuzie | Oct 08, 2008 05:28am | #1

    

   After years of distorting paint cans by hammering on the lid, I tried this: place the lid on the can and lightly tap the lid all around enough to seat it about 1/4 to 1/2 of the way; be careful to not crush anything. Then open your large-jawed vise far enough to accept the can (lid and bottom touching jaw faces), and gently close the vise to completely seat the lid. (It's best if the jaws cover the entire lid and bottom.)

   If you've initially seated the lid enough, the can won't leak when you place it in the vise, and, when fully seated, the top looks like it just came from the factory.

   kreuzie

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   Edited 10/7/2008 10:30 pm ET by kreuzie

   
   

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   Edited 10/7/2008 10:30 pm ET by kreuzie

1. 
   K1500 | Oct 09, 2008 07:04pm | #8

   Or you could just close a can with a rubber mallet.  It's amazing how easily and damage free they close...

1. 
   SantaFeTom | Oct 09, 2008 09:33pm | #12

   I use a rubber mallet to close the cans and I only tap enough to seat the lid. That is why the leakage is such a mystery. I had made the switch to mason jars before switching to Zinsser but don't really like using glass containers in the shop. It was the leaking Zinsser can that really surprised me.

1. 
   davcefai | Oct 09, 2008 10:27pm | #13

   Are the cans coated inside? The alcohol may be dissolving the coating which is sealing the seams.

1. 
   SantaFeTom | Oct 10, 2008 01:14am | #14

   They have a coating but when they start leaking, the coating still looks intact. The coating looks pretty much like the coating that is inside the Zinsser SealCoat cans. I was using Zinsser today and noticed a second sealer coat on the vertical seam but I don't have any of the home center cans left to compare to.

2. 
   davcefai | Oct 10, 2008 07:08am | #17

   OK, in case anybody is interested:This kind of can (known as three-piece) is made from pre-coated sheet metal. The side seam is soldered or welded and then a stripe of coating is applied to the seam to repair the heat damage to the coating.This is not meant to seal the can but to isolate the can contents from the metal. However problems happen and when they do they affect entire batches. 1 million cans is considered a small order in this business.The other point of failure is in the bottom seam. The can end has a sealer around the rim which is compressed when the can is seamed. If the maker used a sealer which is attacked by alcohol then the can would leak from here. Visual inspection of the can should tell you if this is so.Now you know why the drinks industry has switched to 2-piece cans. There is only one point of failure and that is the top seam, which is totally under our control (it's our machine seaming this).

3. 
   drewcboggs | Oct 10, 2008 11:05am | #18

   I'n not a shellac expert..... but for years I put other paints in a zip loc bag, then seal the bag before putting the top on. Also there are now many brands of house paint that are using plastic cans with a metal top,,,, would either of these ideas work ??

4. 
   davcefai | Oct 10, 2008 04:03pm | #21

   Would these work? Probably, but, although the plastic is almost certainly not attacked by alcohol the plasticisers will probably leach out. Then the can becomes brittle. Ever seen what happens to an unsuitable plastic pipe used for petrol?I think the only safe materials to store alcohol greater than 70% concentration (and hence shellac) are polythene (no plasticisers) and glass.

5. 
   MikeHennessy | Oct 10, 2008 02:03pm | #19

   "Are the cans coated inside? The alcohol may be dissolving the coating which is sealing the seams."

   BINGO!

   BTW, I use quart Mason jars. Glass, and it's easier to see when the flakes are disolved fully. To keep the lid from sticking, I wipe the threads and then cover the jar top with plastic wrap, then screw the lid on.

   Mike HennessyPittsburgh, PA

2. 
   K1500 | Oct 10, 2008 01:22am | #15

   I am about to cut up some Zinnser myself.  I haven't had any factory cans leak, but I guess I'll be headed to Mason jars.  I'm glad this discussion came up and I didn't cover my cabinets with leaky Seal Coat!

3. 
   forestgirl | Oct 10, 2008 05:10am | #16

   I would let Zinsser know about the faulty can.  I've had cans of their products sit around for up to 2 years and they've never leaked.  They may be getting a few duds from poor quality control at the can-making factory.

   I only needed to have one failure of an HD can to never go back to that solution (storing very expensive paint).  My new way of closing the cans is to use the sortof-circular end of a paint opener, lay it flat on the edge of the lid, and tap with a small fiberglass hammer, move it around on the lid.  It gets the lid super-tight without squishing the can itself.forestgirl -- you can take the girl out of the forest, but you can't take the forest out of the girl ;-) 

2. 
   SawdustSteve | Oct 08, 2008 05:51am | #2

   Seems strange... I have used shellac for 30+ years and the only time a can would leak was when it got REALLY old. Alcohol has a small water content to it, (it actually absorbs moisture from the air) and the water was rusting the seam of the can. The other time a can would leak was when someone used a VERY heavy hammer to close the lid. Since you're saying the cans were leaking after a few DAYS, I suspect either cheap cans or excess pressure in closing them. For small quantities of shellac, store it in a wide mouth GLASS jar. Put one or two layers of plastic wrap UNDER the lid before screwing it on. The wrap keeps the lid from sticking to the jar and also acts like a gasket.
   SawdustSteve Long Island, NY (E opf NYC)

1. 
   SantaFeTom | Oct 08, 2008 05:09pm | #4

   Using plastic wrap is a great tip. I've had to throw away jars of shellac with lids that wouldn't come off. Thanks.

3. 
   docotter | Oct 08, 2008 06:37am | #3

   I had this exact same problem. I mixed a quart of shellac (1.5 lb cut) from flakes and stored it in a quart can I purchased at HD. About six months after I mixed it, I found it on my bench in a puddle of hardened shellac, which had also leaked off the bench and onto the floor. There was no shellac on the sides of the can -- the seal between the sides and bottom of the can had clearly failed. I've used quite a few of these cans over the years for paint and have never had them fail before. I used the can because I had figured that it was better to have a vessel that would block light, but switched to mason jars after the leak incident.

4. 
   boilerbay | Oct 08, 2008 05:33pm | #5

   AustinTom

   Stopped buying empty cans after 5 in a row leaked. Been using what others here have for about 15 years. Wide mouth Mason with plastic wrap. I don't have much of a problem with sticking anyway as I usually only make up about 10-20 oz at a clip and use it up. Light cuts of superblonde for a sealer. The heavier cuts will tend to be more problematic but with the plastic wrap, not a problem.

   BB

5. 
   Ckenney | Oct 08, 2008 07:38pm | #6

   I seem to remember reading somewhere that you should not store shellac in a metal container, due to reaction between the materials. The commercial products (zinser, et al.) have to line the cans with a special coating.

   Glass or plastic ONLY for shellac.

1. 
   user-83153 | Oct 08, 2008 10:39pm | #7

   Ckenny has it right.

   Mason jars work great.

           Rob

1. 
   brad805 | Oct 09, 2008 07:23pm | #9

   Mason jars are great, but I would wrap the threads with plumbers tape so you can unscrew the cap if you should get a bit of shellac on the rim.

   Brad

1. 
   kreuzie | Oct 09, 2008 08:33pm | #10

   And wear gloves...in case the lid should be really stuck, and the jar shatters. OUCH!!

1. 
   brad805 | Oct 09, 2008 08:42pm | #11

   I have never broke one yet, but spent a bit of time warming with water to get the cap off.  I seem to forget taping.

    

6. 
   fsn | Oct 10, 2008 02:15pm | #20

   I used to have trouble closing paint cans, resorting to a hammer to get the lid seated properly. Since then I got a simple tool from the paint store to open the can.

   I open each can gingerly to avoid any distortion of the can and the lid. I work gently, slowly all around the can. After doing this I can replace the lid without the use of a hammer. I seat the lid, then set it on the floor and push down hard. If the can and the lid aren't bent during opening, it is much easier to get them closed. Easier closing might avoid damage to seams.

   --Whit

   If you have money, buy wood and tools. If you have money left over, buy food and clothing.
1. 
   davcefai | Oct 10, 2008 04:05pm | #22

   I open cans carefully, like you do, but find that the best way to close them is to first push the lid on firmly then place a piece of 3/4" plywood over the whole top and whack it with a mallet.