I decided that it had to become black again, so instead of buying a new saddle I took the risk to paint the leather. First, the saddle was cleaned and degreased with acetone from the drugstore. After that I treated the saddle with 2 layers of black coloured "VG indringverf", some kind of penetrating dye from the local "Mr. Minit".
One layer didn't seem enough to me, so after one day waiting, I applied another layer. Then I polished the saddle with regular black shoe cream.
Now, I think I have the original black colour back. I hope that it will stay like this for a while and that it doens't become brownish again too soon. Some leather paints give an ugly crack or wrinkle effect, so let's hope that that is not the case here. Don't know what happens if I wear white shorts, but that's also not my intention.
Before:
After:
