I like to use simple vaseline. It may darken the glove a bit, but it is typically just temporary. Vaseline conditions the glove nicely and moistens the leather with no staining, hardening, or other ill effects.
You might try it first on a "beater" glove you don't care about. The moisture will initially darken the leather, but after a few weeks, the glove usually retains its original tan color.
Hope this helps!
|