We probably should have noticed this sooner, but …
Yes, that can really does did contain white paint!
It cleaned up about as well as you’d expect, which is to say not very well at all:
Fortunately, we’re not particularly fussy about shelves in the Basement Laboratory Paint Storage Wing.
Memo to Self: Just throw the nearly empty paint cans out, OK?
The Smell of Molten Projects in the Morning 
I got a nice surprise last fall after opening an 18+ year old paint can which contained only about an inch of paint…it stirred up and worked just like it did when new. It was Pittsburgh paint, in a plastic bucket. It’s about 50/50 with latex paint in the lined steel cans.
The Force is strong with you!
Some of the newer buckets have a plastic base with a steel sealing ring around the top. Give ’em a few years and let’s see what horrors lurk within…
I think you are talking about the Behr type cans with a plastic body, but the steel lid to can seal is a ring pressed on the top.
IFF you keep the steel ring from getting clobbered or clogged from paint buildup you should do fine. I’ve had such last at least 7 years. Keep the liquid away from the seam and it should last. I wouldn’t store those types upside down, though. The hard part is keeping the lids and seal ring clean and undamaged.
Dad taught me to swipe the paint out of the lid and ring with the brush before pressing the can closed with foot pressure. I suppose if I painted more often, I’d remember to do that more often, too, because it really works. [sigh]
I think we should look deeper into the lesson at hand. I think the real lesson is that any metal container often increases the internal condensation with temperature swings. Even the tiniest pinhole when replacing the lid is more than enough to cause the internal condensation. The same plastic container likely had the same air leak, but not the condensation. I dare say that any metal container in a basement subject to temperature swings is subject to a similiar fate-paint or not. And that’s the other side of the story too. An unopened can is likely perfectly sealed and doesn’t condense water on the inside, but once opened, it never seals again.
Taking the lesson further- metal gas cans anyone with the common E10-E10 fuel? Care to take a guess at what that mess looks like?
Aye, there’s the rub. Even when I try to clean the sealing ring, it never works quite right. An upcoming Monthly Science will dump the basement temperature record for the last few years, so we can puzzle over how much swing happens. There’s not much of a daily swing, but the annual range is about 50 to 70 F, which is probably enough to ram air into the paint cans.
I got rid of a whole bunch of hideous yellow latex paint (that came with the house) by spraying the raw wood storage shelves (which also came with the house); they’re in the Basement Laboratory, where hideous yellow fits right in. The rest of the paint, we’re stuck with, as there’s no good way to dispose of the stuff. [sigh]
They scare me, too. I built a little pallet that keeps my can up off the floor, so that there’s no dead air underneath. When I look inside (which I’ll do later today when I restock for the coming storm), the bottom always looks just as good as new.
One thing about the plastic cans is the lack of a bottom seam to seep. I’ll get several years from a used gallon of paint, however mostly empty 5 gallon paint pails are iffy due to the high surface area. In all cases, I keep the paint from freezing to avoid problems.
Some steel cans have poor sealing to various products. Copper-bearing wood preservative will seep–I keep my quart in a coffee can, now with green goop on the bottom. The champion is old-school methylene chloride paint stripper. Use it once and the steel can starts corroding (perhaps HCl generation from water vapor). It has other effects, decidedly unpleasant, so when alternatives came out, I stopped using it.
My only steel gas can holds 2-stroke mix and that’s done with non-oxy gasoline. I’ll do a gallon at a time and try to use it up fast. Lots of cultivating/weed whacking and general chainsaw work, so it doesn’t go sour. 2-strokes and E>0 don’t do well together. Small engines and E10, similarly, even if you run the engine dry. The varnish will clog a passage, as we learned on a 2HP Honda outboard. That was a $100 lesson.
That stuff is nasty, but none of the newfangled strippers bothered the old-school finish on the plain-front kitchen cabinets. Redoing each cabinet probably whacked a month off my life, but they look lovely and are exactly what we wanted.
I’ve discovered adding a touch of choke on our old engines compensates for the additional oxygenate; otherwise, they run red-hot lean. The newer ones seem happy with the stuff, which is Good Thing because they don’t have chokes…
That, plus adding Sta-Bil to every can, regardless of how long I plan to have it around, seems to be working.
Haven’t used Sta-Bil in a while, since I have ready access to non-oxygenated fuel (the local fuel terminal and the marina both sell it). I have a couple of generators and the 5.5KW hated a break of a couple of months unless I drained the float bowl. Since switching to non-oxy, it hasn’t been a problem, though I still warm up the generators once a month. Even the Honda 2HP is OK with a winter break and fuel in the tank (but with the carb run dry).
At 4000′ elevation, choking/starting a small engine is still a fine art…