odd.. That might actually
be suede.
OK. For that, look for cleaning and care instructions for suede shoes.
One common denominator in care instruction is something like this:
For hard-to-remove stains—or, if you wear them during the winter, for salt stains—the best method is to use a solution of two parts water, one part white vinegar. Apply a small amount of the solution with a soft rag or a towel, and then let it dry. Once it's dry, go over it lightly with your suede brush.
A suede brush is a very soft bristled brush that looks like a scrub brush. White vinyl eraser is often used to help lift scuffs off the delicate surface as well, and is paired in this example
Nubuck is thicker, and tougher than suede. You could probably clean nubuck with the saddle soap, if you were really gentle, and did a cleanup with a damp cloth afterward. Suede? Not so much. It's sensitive shit.
...
That COULD also be "Rough-out" leather though... How thick is the leather?
Full grain leather is the full thickness of the hide, and is the strongest and sturdiest stuff out there. It's premo stuff, and costs a mint if it is defect free.
Top grain leather and Nubuck will be about the same thickness, and have had the top of the hide sanded to either disguise defects/blemishes in the leather, or to give it the suede like texture; both will be appreciably thinner than full grain hides, but still much thicker than suedes.
Suedes have had the entire top surface of the leather sanded off, and consists entirely of "split." This is the weakest part of the hide, and the least durable. Its claim to fame is that it is soft and velvety to the touch. It is not really meant for durable goods, and is meant more for luxury items.
Here a section cut of full grain leather.
Top grain leather sands (and polishes) the top of the grain off, to disguise imperfections.
Nubuck sands down to just above the "junction", and has a velvety feel.
Suede is the bottom most portion of the hide, and has the top grain layers completely removed.
This 'could' be a 'rough-out' piece of full grain hide, that was of inferior quality for use as normal leather. (Eg, scars, other blemishes, et al.) It would be durable, as it is full thickness, but would be treated like suede, because it is inside out.
You could probably use saddle soap on rough-out, but not on suede.