Left without care, the dirt built up until it turned black. Don't give up and assume the only option is to throw it away. According to Yasutomi, “in most cases, dirt on leather comes clean if you wash it with water.”
People tend to think that getting leather wet causes water stains. That, he says, is a big misconception. Wetting leather lifts the dirt out of it. It is true that if you wet only part of it, the lifted dirt gathers at the boundary and settles there as a water stain. But if you wet the whole piece and rinse the lifted dirt away, no stain forms. Note, however, that washing has no effect on leather treated to repel water. Test an inconspicuous spot to see whether water soaks in before you begin.
Step 1. Rough-clean the dirt
Put some leather shampoo on a cloth and scrub the dirtiest areas. The trick is to always use a clean part of the cloth: as soon as it gets even slightly dirty, don't be lazy—rewrap it.
Step 2. Use your fingernails on stubborn dirt
Remove stubborn dirt by scratching at it with your fingernails. Nubuck is a tough leather, so it can take vigorous rubbing. Wash as if scraping out the dirt that has worked its way deep into the leather.
Step 3. Wash in water with shampoo
Fill a basin with water and add shampoo, then put the gloves in and wash them. This method is only for hard-wearing nubuck; smooth leathers such as vegetable-tanned nume leather should instead be wiped with a damp cloth.
Step 4. Knead-wash
Soak the gloves in the basin and wash them by kneading. For heavily soiled areas such as the fingertips, rub the leather against itself to work the dirt out. Turn the gloves inside out and wash the inside thoroughly as well.
Step 5. Rinse out the detergent in clean water
Change to clean water and rinse out the detergent, repeatedly soaking and wringing until the slipperiness is gone. The photo on the left shows the gloves rinsed and wrung out. Reshape them and dry in the shade.
Step 6. Dry and check for remaining dirt
If dirt remains after drying, wash again. Leather shrinks as it dries, but putting the gloves on and flexing them loosens the leather back to shape. In this case the color had faded, so a coloring agent was also applied.
Step 7. Raise the nap with a rubber brush
Washing flattens the nap of nubuck, so brush it up with a rubber brush. Brushing also removes still more dirt. Use the corner of the brush to reach every nook.
Step 8. Finish by replenishing nutrients
Finally, spray on a conditioner to replace the oils lost in washing. It also waterproofs the leather and makes it more resistant to dirt. For smooth leathers such as nume leather, apply a moisturizing cream instead.
Step 9. Done!
The black grime is now barely noticeable. Once dirt works its way into leather it is hard to remove, so regular care matters. Gloves in particular touch the skin directly, so you want to keep them clean.
