Exploding rattle can

[E5 Charger]

Friday night I heard a loud bang from my garage and went in to see what it was. An old can of spray paint exploded in the cupboard it was in and actually opened the doors. There was black paint everywhere! On my tool box, the walls, the floor, but worst of all my 2013 Grand Cherokee! I actually was able to remove the splatter from the Jeep using a combination of a clay bar, tar and bug remover and some liquid carnuba wax. I was lucky it was small dots of paint and not a pour of it. I was thinking if that didn't work I would have to have it buffed out.
All of my spray paint has now been moved to the basement. Just a heads up that this can happen.

[ws23rt]

Very good topic.

Those rattle cans are a potential.

And any one that welds or makes sparks should put the spray cans away.

On a job site I worked on --a welder working on fab a table was seriously burned when a rattle can went up in flames from a welding splatter that landed on a can. The metal that holds back the stuff inside is very thin.

[UFO]

Was a hot vehicle parked in there a short time before the bang?
I had parked a car in the garage, a short time later walked past the outlet for the furnace and heard the fan running. In a panic wondering why in the hell the furnace is running , I found that the heat dissipating had pegged the thermostat. Confusing the fan motor into thinking the burner was on.

[E5 Charger]

I don't think the Jeep was that hot, but it was 27ºC/80ºF outside and I just started up a compressor. It was done filling up 5 minutes before this happened. I checked and it wasn't touching the wall or cabinet, but was about two feet from the cabinet. The cabinet is mounted on the wall, so doesn't touch the floor. I'm just lucky I wasn't walking by when it happened, it would have been level with my face.

[Chad L. Magee]

Gas laws at work:  (Sorry but this is a scientific answer to the event)

The air compressor is the likely culprit in this case.  When gases are compressed (increasing pressure) into a constant volume (as in an air tank), the temperature of the gas will go up.  This is called either Gay-Lussac's Law or Amonton's Law.  (If you release air from the compressed tank, the container will cool due to the drop in gas pressure.  Air duster cans have warning labels about this issue.)  Since you had recently compressed air into the tank, the metal surface of the tank would have been quite hot to the touch, as any thermal energy from the gas molecules would have been transferred to the inner metal surface upon contact.  Metals tend to dissipate heat (low specific heat values), so the thermal energy would have been given to the surrounding environment area (which includes the spray can).  As the temperature of the spray can increased, so would the pressure of the gas inside the can until the metal can gave way.  One way to prevent this is to put a thermal blockage between the area that the paint cans are being stored and the air compressor....

[E5 Charger]

My basement is now going to be my thermal blockage. 

[ws23rt]

Just to back up a bit for discussion.  The can was in a cabinet about two feet from the compressor. The compressor will get hot from filling but not a particularly hazardous temp. 

I'm thinking the can had a flaw from manufacture or been damaged in some way to allow it to fail at such a low temp. The total of the conditions obviously was too much and is still a good example for why we all should rethink where we store these little bombs.

[Lord Warlock]

Its a conspiracy, no its these cans...these are defective cans...someone hates these cans.....more cans....  says the jerk

I had a can do something similar last week.  I built a shelf above the doorway to my garage, about even with the garage door tracks, mainly someplace to store smaller items like polish or paint cans a quart or less in size.  Its a sturdy shelf, but when you shut the door hard it vibrates the door frame, and the shelf evidently shakes and occasionally I'll hear something drop as I walk out.  I try to keep stuff away from the edge, but get complacent over time.  Anyway, I had a half empty spray can of Totally Auto's Organisol that I was saving to put a final coat on the tail panel, anyway, the can took a swan dive off the shelf, missed the workbench below it, and hit the cement floor just where it would cause it to spray out the remnants of the can all over the carpet and garage floor near the doorway.  

It could have been worse, if the can had rolled six inches closer to the charger, I'd have dried organisol all over the right front rim or fender.  At least it didn't damage the charger...this time.  I had a hook fail on my pegboard somehow which let a can fall onto one end of a shelf launching items on the shelf to the floor, then the board from the shelf managed to jump almost six feet from the wall to the top of my front fender and put a dent in the top of the fender where the corner hit it.  One day charger had no dents, next day it had a new dent...but was securely stored in a garage...a two car garage...with only one car parked in the middle and murphy still got me.    Think I'm going to have to add a lip on that shelf, can't stop the door from slamming...if you leave it open the crossflow from the main garage door will blow the side access door shut.

[472 R/T SE]

Thanks Chad.  You actually explained that well enough for my foggy brain to understand.  You da' man.   



Now...I have about 50-60 aerosol cans out here in the garage.   

[Chad L. Magee]

Thanks Chad.  You actually explained that well enough for my foggy brain to understand.  You da' man.   



Now...I have about 50-60 aerosol cans out here in the garage.   

Glad I could help in this situation.  I teach a section of gas laws in each of my chemistry classes, each with a life/death consequence depending on how they are used/misused.  Even good old soda pop follows Henry's gas law. 

As for a thermal barrier, my choice would be containers of water.  Water has a high specific heat capacity, so it can absorb a large amount of energy before the temperature goes up.  If that is not an option, there are heat shield blankets that can be bought.  Another option would be a unplugged (does not have to work) deep chest freezer to store the paint cans in.

[ws23rt]

The old freezer (working or not) is a great idea for old paint storage.
Another thought that came to mind is not leaving these things in your car on a hot day. (even with the windows cracked).

[E5 Charger]

Could you imagine what the interior would look like if it exploded? All the polishing in the world wouldn't help!

[ikbrown]

Eeep! I have probably about 20 spray cans and probably 10 gallons of paint (most 1/4 full or so leftover from just completing painting the interior of my house). I live in Sacramento and my garage unfortunately is not insulated. On days when it's in the 100s I wouldn't be surprised if my garage is 110+ degrees F after work when both my car and my wife's are in there heating the place up even further.

Guess I should find a new place to store my spray paint cans until I insulate the ceiling to help with the heat! I certainly don't want any exploding from the heat since they're just in a bookshelf facing my Saabaru!