Henk Bos wasn't the owner of the mine but his text on natural stones is essential reading for anyone interested in the subject. The mine owner is Maurice Celis, a great guy but not necessarily an expert in honing razors.
These videos may change a few opinions about the use of coticules as finishers.... No slurry in sight!
These videos may change a few opinions about the use of coticules as finishers.... No slurry in sight!