Darkening works best on unfinished vegetable-tanned leather. Oil, sunlight, dye, antique paste, vinegaroon and strong coffee can all darken it, but by different amounts. Chrome-tanned leather with a factory finish resists most of these until you remove the finish with a deglazer.
Before you start
- Check the tanning. Vegetable-tanned leather usually soaks up a drop of water and darkens where it lands. Finished chrome-tan usually beads the water instead. For more checks, see how to identify chrome-tanned leather.
- Test every method on a scrap of the same hide. Results vary between hides.
- Plan for permanence. Darkening is hard to undo, and an over-dark result cannot easily be reversed. Go a little at a time.
Darkening with oil
Neatsfoot oil darkens vegetable-tanned leather noticeably. Pure neatsfoot is the usual choice, since compound neatsfoot contains petroleum oils. Mink oil and many conditioners also darken leather, usually less than neatsfoot.
Apply oil in thin coats, wipe off the excess and let the leather absorb it. Avoid motor oil and heavy mineral oil, which can degrade and damage leather over time. Coconut and other cooking oils are not good choices either, because they can go rancid.
For more on oiling, see should you oil the rough side of leather.
Darkening with sunlight
Sunlight darkens vegetable-tanned leather over hours to days. Oiling it first speeds the process. The effect depends on the leather and the strength of the sun, so check it often.
Sun can also fade leather, so use this method only on undyed veg-tan. Condition the leather afterward, since the sun can dry it out.
Darkening with dye
Leather dye darkens leather when applied in several thin coats with a dauber or airbrush. Each coat darkens the color further. Let each coat dry before the next, then buff, and seal with a balm or finisher such as Resolene, Bag Kote or Tan-Kote.
Dye looks lighter when dry and darker once oil or finish goes on, so judge the final color after finishing. For dye types, see water-based vs alcohol leather dye.
Darkening with antique
Antique finish darkens mainly in tooled recesses and pores, not evenly across the surface. It creates contrast rather than an overall darker color. For the method, see how to make leather look aged.
Vinegaroon for grey and black tones
Vinegaroon is a solution of iron acetate. On vegetable-tanned leather, it reacts with the tannins and turns the leather from grey to black.
Making vinegaroon
Put degreased steel wool in white vinegar. Leave the jar loosely covered for several days to a couple of weeks, then strain the liquid.
After treating the leather, rinse or neutralize it. Some makers neutralize with a baking soda solution, and some pre-treat with tannin, such as strong tea, for a deeper black. Then oil the leather, since the process can dry it out.
Vinegaroon does not work on chrome-tanned leather. Test it on a scrap first.
Safety with vinegaroon
The reaction releases hydrogen gas. Vent the jar, never seal it tightly, and keep it away from flames and sparks. Work in a well-ventilated area.
Coffee and tea
Strong black coffee or tea adds tannin and darkens leather slightly. The effect is subtle and uneven, so it suits a light tint. Test first.
Darkening finished leather
Finished leather usually needs to be deglazed before most methods will work. Strip the finish with a deglazer, then dye. A colored cream or recoloring balm is another option for finished leather. Deglazers are flammable, so ventilate and wear gloves. For recoloring and cleaning, see DIY leather shine.
Common misconceptions
- Dyes and oils can lighten leather. They cannot. Darkening only goes one way.
- Vinegaroon works on any leather. It does not work on chrome-tanned leather.
- One heavy coat of dye is better. It blotches and rubs off. Several thin coats work better.
- Darkening is reversible. It is effectively permanent, so go slowly.
Safety
Vent vinegaroon containers and never seal them tightly. Alcohol dyes are flammable, so ventilate and keep them away from flames. Wear nitrile gloves when handling any dye.
For the wider finishing sequence, see leather finishing.