Learn English – term for accumulated dirt on the outside of your hands and feet

As I sat in the steam room after half-killing myself at the gym earlier today, contemplating the meaning of life, I noticed that a certain amount of dirt had accumulated on the lateral sides of my – by that point rather pruny and wrinkly – hands, requiring a bit of scrubbing in the shower to become properly clean again.

I suddenly remembered always being told off as a kid by my parents and teachers and other such boring people for not scrubbing the sides of my hands properly, allowing for dirt to cake up there, even if the rest of the hand was clean enough; and similarly for the feet, where it typically builds up on the lateral side of the hindfoot, between the lower end of the fibula and the cuboid bone.

Into my mind popped the Danish word gravrust (referring literally to the type of corrosion called ‘pitting’ in English), which is used metaphorically for this specific type of dirt on the outside of the hands and feet that builds up over time if you’re not careful to scrub the sides properly when washing.¹

I don’t think I’ve heard this word since my days as a kid when boring adults were forever telling me to scrub it off, but I seem to recall it being used fairly often back then (rather more often that I would have liked, because it usually meant I had to go and wash my hands again).

It occurred to me that I don’t know of an English term for this kind of stubborn dirt, most commonly seen on kids who enjoy wreaking havoc in the garden rather more than scrubbing their hands to remove what’s left of said garden afterwards. Since such a preference is not unusual in children, I’m guessing the condition is well-known to most parents in English-speaking countries as well… but after about five minutes of battling with Google, I am no wiser as to what they call it. I can’t find anyone mentioning it in any terms that I can think of to Google for.

There are of course any number of general terms for dirty children (grimy, grubby for the kids themselves; crud, muck, smut for the dirt), but they’re all quite general – they just refer to dirt on the body in general and don’t carry the connotation of being resistant to casual washing. Gravrust, conversely, refers to dirt which is in a position that tends to be missed when washing your hands or feet (the lateral edges), and therefore tends to build up more easily, to the point that vigorous scrubbing is required to get rid of it.

Is there a specific word or expression for this in English, beyond descriptive phrases like caked dirt on the sides of your hands?

Note: Dialectal and regional terms are welcome. The Danish word is quite colloquial and, as mentioned, somewhat limited in scope, and it’s fine if any English equivalent is too.

^{1 A quick dictionary and Google search reveals that it can be used for caked dirt elsewhere as well, but I’ve only ever heard it used to refer to the stuff that builds up on the lateral sides of hands and feet.}