As a rule, leather goods should not be allowed to get wet. This is because as the water dries, dirt and oils that had soaked into the leather migrate to the boundary between the wet and dry areas and settle there as a stain. Unlike surface dirt, such stains cannot be removed simply by polishing the surface.
The best way to remove such water stains is to wet the entire piece of leather so that the dirt and oils can be moved out of place and removed. The key, therefore, is to let the leather soak up plenty of water. Wetting only the stained area will just create a new stain along the edge of the wet patch, so the essential thing is to wet the whole piece.
Once the dirt lifted by wetting the leather has been removed, let it dry completely and restore a suitable amount of oil with a conditioning cream or the like, and it will be as good as before.
Step 1. Check where the stains are
First, check where the stains are and what kind of stains they are. Then soak a towel with plenty of water. The aim is to “wet” the leather, so make the towel dripping wet.
Step 2. Wet the whole surface as you wipe
Wipe in broad strokes as if removing dirt, letting the water soak into the leather. The point is to saturate the whole surface until the stains can no longer be seen. Think of how hand-washing laundry works the dirt loose.
Step 3. Once the stains disappear, you're set
The whole surface, evenly saturated with water. Unless the water penetrates right into the leather, you will end up creating stains instead. If a stain is still visible on the surface at this stage, it is most likely an oil stain.
Step 4. Wet the inside too, watching for stains
The inside of the wallet has no water stains, but wipe it with water in the same way as the outside to remove dirt. It would defeat the purpose to create water stains by wetting it, though, so work evenly.
Step 5. Dry and check that the dirt is gone
Dry in the shade in a well-ventilated place. Shape the wallet and dry it on a clean towel or similar, keeping the leather surfaces from pressing against each other as far as possible. If stains remain after drying, repeat the wet-wiping and drying a few times.
Step 6. Clean and replenish the oils
Once completely dry, remove surface dirt with an emulsified cleaner containing conditioning ingredients. Hand grime and the like is removed at this stage. It also serves to give the leather oils, so work it in well.
Step 7. Saddle soap for stubborn dirt
If the oily dirt is severe, wash the whole piece with saddle soap (a soap for leather). Apply the soap with a sponge so as to lift the dirt out. After washing and drying, condition with an emulsified cream.
Step 8. Done!
Even after a thorough soaking, the wallet is as good as before once it is completely dry and treated with conditioning cream. The offending water stains are gone to the point where you cannot tell where they were, and the overall darkening has faded too.
