Paint Your Wagon . . . and your fence, and your picnic table, and your porch, and every other surface
Tom just came upstairs and I asked him if he had a good subject for this. With no hesitation, he said, "Paint."
The issue is specifically oil-based paints, varnishes, and stains. It used to be that you could keep these around for years. If you opened a partial can, even years later, you could skim off the top and the rest was still viable. No more. Within the last six months to a year, a entire can "gels" and becomes unusable within a couple of months. So, once you open a can, you'd better be prepared to use the entire thing (hence, the title of this entry).
So, you say, why don't you just buy what you need? Well, that's a whole 'nother issue. Have you ever price-compared a quart vs. a gallon? It would cost three times as much! And what if you need slightly more than a quart? You buy two quarts, and it costs more than a gallon. So you buy the gallon, and well over half of it goes bad before you have a chance to use it up.
Tom just came back up and told me to add joint compound and vinyl spackle to the list. They used to keep forever, but now mold in short order. Apparently, the manufacturers have ceased to include some sort of mildew-preventing agent.
The leftovers of these products are considered "hazardous waste," and Lincoln doesn't make it very easy to get rid of them (only at certain places, and only on certain dates), so it's not just the pocketbook that gets hurt, but the environment. Did the manufacturers of these products decide there were too many people like Tom?