Atelier
Leather — Patina tolerances
Vegetable-tanned leather is tanned with bark extracts, not chromium salts. The process takes months, costs more, and produces the one kind of hide that ages into a better surface than it started with. The tolerances below define normal behaviour.
Colour
Light and the oils of the hand take a chestnut bifold two or three shades deeper in the first year, unevenly, where it is touched most. This is the patina. There is nothing to correct.
Marks
A scratch in vegetable-tanned hide rubs out with a warm finger: the fibres move rather than tear. Deeper marks stay and, after a year, read as record rather than fault.
Maintenance
A neutral cream twice a year, worked in thinly with a cloth and left overnight. No polish: it sits on the surface and cracks. No saddle soap: it strips the oils the hide needs. No mink oil: it darkens far beyond intent.
Water
Dry at room temperature, away from heat. A radiator makes the fibres brittle in an afternoon. A soaked piece is stuffed with paper to hold its shape and left alone.
Failure mode
Not use. Neglect and heat. A wallet carried daily for ten years outlasts one kept in a drawer, because the hand conditions it.