That’s how cotis were used for a century or more. I don’t recall ever seeing a vintage Coticule with a slurry stone or instructions to make a slurry. The most common instructions were to use with water, oil, or lather.
Dr Matt's technique works amazingly well for some stones but not for others. If I remember correctly he hones on synths to 8K, strops, and then does his water only thing.
What I have found is that you can replace the synth progression with a dilucot on the coticule. The important step is stropping before moving to the water, and then everything works just like Dr Matt. Or you can hone the razor on synths and finish with the coticule. On the right coticule this is improved further by cycling between stropping and finishing, especially on a flax linen strop. I have found that the technique works especially well with my La Grise rocks.
On my LGJs the technique leaves a very uninspiring edge - I don't like the technique and find lather a better finishing medium. For Le Verte and LPB and La Nouvelle Veine it's a completely different finish. I have a couple of vintage cotis that only work with oil. What I am trying to say is that coticules vary. Try the technique. If it works with your stone - bingo! but if it doesn't don't be disheartened - experiment!
Coti slurry was used on the brackets hone for beveling, but yeah I can’t say that I’ve seen a reference to slurry for use ON the coticule on any of my boxed vintages. Ironic because other stones like Thuris did. Not to say it doesn’t work. It does. But it’s more of a parlor trick or else born of necessity than an ideal method.
I think the significant use of dilucot came about BECAUSE people were starved for alternatives back in the day. (8-15 yrs ago)Now we’ve started using a dozen different great options and it’s just another one of these. Not worst or best.
Same thing as jnats. You can work and finesse a fine edge from a less than stellar jnat, but these days I’m into one thin slurry and boom! I’m done and have a first class edge. I too look for stones that can do that.
Never use slurry on any of my Coticules. They are finishers. Of course you can create a slurry to make it cut more, but so you can with basically any other hone, natural or man made.
I believe Slurry is a novelty thing to compete in today’s markets where synthetics are kings
I hone up to 1u film and in some of my razors (when I want a smoother edge) I finish on the coticule with water: 15 light laps, strop on linen, 15 light laps, 10 light laps under running water, strop on linen and leather
Interesting comments - for me it's about the individual stone itself. Some of my fine coticules don't work with slurry - a couple don't even work well with water and need a very fine oil. These will produce an extremely keen edge and work perfectly as finishers after other stones. I have one that will treetop as if I have come off pastes.
I have another stone which has very large smooth garnets. Using this without slurry is completely pointless. It is useless. But using the stone in a very controlled dilucot progression, the resulting edge is not so sharp but, boy, what delightful edge it produces! In fact I get my closest shaves from that stone because the razor is more forgiving and I can really push the angles without causing irritation.
If I stopped using dilucot I would miss out on some of my best all time shaves. I love my fine finishers. I use those in in a progression after other stones in the way others describe but I don't rate them as better stones than my less fine stones.
Of course I haven't a clue about JNATs - what I am saying only applies to my experience with coticules.