Heat shrink tubing from Home Depot, and a heat gun from a local hobby shop, and you have replaceable black finish. You can even buy heat shrink tubing in very small sizes that would work exceptionally well on wire type clips. This stuff last a long time as long as you do not brush up against any hard objects. Also some auto parts stores sell a very low grade traction tape that also works well, and sticks very well .I have several knives with this on them and they have been that way for many years.
I do not even remove the clip to put the tubing on. Cut a piece to length, take a small screwdriver and insert through the tubing. Position the tubing at the front of the clip and use the screwdriver to lift the front of the clip so you can slide the tubing on. I put a piece of cardboard in between the clip and the rest of the knife while using the heat gun to shrink the tubing.
Pictured is an old original model Spyderco Military from 1992.
A hair dryer is not hot enough. You have to have a real heat gun. Most model airplane hobby shops sell a cheap one for applying Monokote to aircraft frames. That is what I use, have had it for a very long time.