I have been looking into getting a Coticule/BBW for down the line when I want to try out naturals and my skill with the Norton is up to snuff. My question is: For making slurry on the BBW side do I need a cotigura with a BBW side? If so is there a ready supply of slurry stones with a BBW side? I am actually hoping so as I would like to try it out. I have read that some just use the yellow coticule to make slurry on a BBW side. Any input would be great.