Quiver Straps Marring Bow Finish

[Whip]

For any of you that have used a post-catalyzed varnish finish, have you run into problems with rubber quiver straps leaving stains in the finish?  
I am using ML Campbell Krystal.  From what I understand it is a similar type finish to Fullerplast.  I have a customer who used a strap on bow quiver on a bow that I had redone and it left dark marks in the finish.
Any suggestions?  Are catalyzed varnishes not compatible with rubber straps?  
Thanks!

[Crooked Stic]

BTW Krystal is a lot better than FP.I would suggest having him put paste wax on the rubber straps.