Aproning is the old-fashioned way of figuring out if the syrup is thick enough. Before thermometers and hydrometers and all that fancy stuff, people just looked at the syrup dripping off the end of a spoon and knew by looking at it when it was done. Explanations of what the appropriate degree of aproning is are pretty damn vague, let me tell you. The common explanation is that when the syrup no longer comes off the edge of a spatula in individual drips, but instead kind of hangs together in a sheet, that's aproning.
All well and good, but what the hell does that actually mean? It means you'd better reduce the syrup a few times and learn by experience. First, is it supposed to be a metal spatula, like a pancake flipper? Or a rubber spatula, like you use to scrape the sides of the bowl when baking? Or something wooden? I figured wood was safest, because metal retains heat and therefore keeps the syrup hotter even when it's dripping off, thereby making it thinner. Also, this is an old-fashioned way of testing, and old-fashioned kitchen utensils were almost invariably wood, so I used a flat wooden spoon to test.
I also was terrified of over-boiling and getting the syrup at all grainy--which apparently can happen pretty quick at the end--so at first I stopped when I saw ANY sign of the drops starting to pull together on the edge of the spoon. But then, after it was cooled, the syrup was still kind of thin. So I did it again.
That's the nice thing with boiling syrup: You can do it over and over. Nice of it to be so forgiving.
I've finally figured out what the aproning looks like when the syrup reaches the right consistency, but I'll be damned if I can explain it. And that's the thing: NO ONE can explain it. And it's not like there are a lot of videos out there showing maple syrup aproning. Or any videos, based on a very cursory online search. You just have to . . . know. You have to have a visual in your mind. And you either get that visual by trial and error, or by watching someone who knows what to do. And who is that person, really? No one I know. Not even the MiL, who is a font of wisdom when it comes to old-fashioned kitchen knowledge, knew what the hell syrup aproning looked like. Or when sauerkraut is done, um, sauering. Or any of the other countless small bits of knowledge that have kind of disappeared.
Except now I know what aproning looks like, so anyone who needs a first-hand tutorial, just let me know. Knowledge is power. And the key to perfect maple syrup.