Weird excrement

[Hobbes]

I was looking under my desk to retrieve a kit part I'd dropped, when to my astonishment I came across a tinlet lid. Its presence there puzzled me a bit, as I was quite sure I hadn't put it there, hadn't lost it etc. So I checked my paint (which sits on a shelf about 3 m away from where I found the lid), and sure enough, one tinlet was missing its lid. The tinlet was new, unused, and filled to the brim (literally). Found a spot of dried paint on the underside of the shelf above the tinlet [1] so this must have happend at least a day or two ago, but the open tinlet hadn't dried out yet.  

I'm stirring the paint now, and it's full of air bubbles. Most of the solvent seems to be gone, what's left is a gooey mess.

This has never happened to me before.  



1: and that was the extent of the damage, it seems. Could have been a lot worse.

edit: I see my title has gotten auto-edited? It wasn't as formal when I wrote it...

[Howard of Effingham]

hmm, this happens to me sometimes too.

ok so not exactly shooting across the room but for certain i need to clamp the lid down
to prevent it landing somewhere on the bench. as far as i can see there are some very
slight differences in the way that the lids and the openings are manufactured and some
lids go back on much easier and tighter than others.

[Hobbes]

Does it happen only with xtracolor, or with Humbrol, Revell etc. as well?  

[Howard of Effingham]

Does it happen only with xtracolor, or with Humbrol, Revell etc. as well?

humbrol mostly harro. the lid on the revell paints is a snugger fit.

[P1127]

David Hannant p[osted on this on either Hyperscale or Airliners yahoo group - IIRC it's to do with moisture in the tin, but a search may reveal more

[Mossie]

I think what happens is like what P1127 mentioned, if you use the tin in a humid environment, moisture settles on the surface of the paint.  If you close it up & put it somewhere warm, the pressure builds up & the top can pop off.  Ususally it isn't this extreme, but often you can have a situation where the top flips up at you as you take it off.  The main way to avoid it happening is to keep your paints in a cool, dry environment & can happy with any oil based paints.  Hobbes, if your shelf is near a heater, or a window, or even just in a warm room with the summer coming up, it might happen.  I keep mine in a cool garage, within a tool box & I've never had a problem.

The other possibility is if it's a metalic paint.  Again, it's if it's hot, the aluminium paste in the paint will explode, it's simillar to the aluminium compounds in solid rocket boosters.  The temperature has to be fairly extreme, but it's suprising how hot they'll get left in the sun next to a window, probably wouldn't happen with paint though.  I once saw this happening in my first job in a paints lab, the analytical chemist (he really should have known better) warmed some of this pure paste in our oven.  He forgot about it & it made this loud bang, it made one hell of a mess of the oven!

Basically, store your tinlets in the conditions stated on them & you shouldn't have a problem.

[elmayerle]

That's as amusing as what happened at a chem lab my father was a chemist at.  One of the other chemists spilled some iodine in the sink and then wiped it up using cleaner, ammonia-based cleaner.  The resulting film, when dry, form Nitrogen Tri-Iodide crystals and they went off when my father turned the water on to wash his hands - nothing major, just a lot of popping, but 'twas quite a surprise; his co-worker was a bit embarrassed than he hadn't realized what he'd done.