How important is it to use an escher rubbing stone with an escher? I have a small (5 x 1) Escher but no rubbing stone; I'm thinking of just using a Coticule rubbing stone. But I do want the slurry to be an escher slurry, not a Coticule slurry, since one of the main reasons I'm trying out this escher is to see the difference between it and a coticule.

I wonder if anyone who uses Eschers has a suggestion...