I have a light colored cowhide leather strop. Right in the middle of the strop the leather is turing black, presumably from metal particles I guess. I've never stripped on it with a dirty razor. Is that normal? Is there anything I can clean it with?
Strops are generally very tolerant of cleaning. I recommend a very lightly damp lint free rag. Cheap microfiber works great. Get it soggy wet and then wring out as much of the water as you can so that it is only slightly damp. Then vigorously rub. Don't be afraid to get it on a table and really go after it to get it clean. Then I let it sit for a day to let any water evaporate and gauge the strop to see if it needs any conditioner. If it does a tiny tiny amount of neatsfoot oil will usually do the trick. Two drops rubbed between my palms to get it warm and then vigorous palm rubbing will apply just a tiny bit of needed conditioner. Remember you can always add, but it is the devil to remove so think less is more.