Thread: Hardness of coticule based on slurry color

If you can scratch a coticule with your fingernail that's one soft coticule. There aren't too many minerals you can do that to, talc, gypsum, maybe calcite.

Originally Posted by Oak

My fault for being unclear.

I used the DMT on the razor to set the bevel, but the scratches left behind seemed to prevent a smooth shave, even after a coti/slurry, BBW, coti/water progression. To remedy this, I went back to the coti with slurry. Still not much change. So, to make some progress, I experimented with using more pressure and circular strokes, and, voila, darkened slurry for the first time.

Sounds like this must be a pretty hard coticule. I may need a different stone to bridge the gap between a 1200 DMT and a BBW. I'd be curious to hear different opinions, though.

Thanks again

When you went to coticule with slurry, how many circular strokes did you do total before you checked the bevel? Sometimes it can take quite a while. Yes, the coti with slurry cuts relatively fast, but it's not SUPER fast (in most cases.)

Also, the slurry doesn't have to be really thick. Just the consistency of milk. If it's like a paste, then you have it way too thick.

I don't own a 1200 DMT, but I think you should be able to go to a coticule after that. I go from a Norton 1k to Coti and have had no problems. You may have to do more passes than you have already, but I'm sure it will come around eventually

I actually haven't had a chance to finish it out yet. I didn't keep track of the time, but it wasn't long at all. I checked the edge through a 100x scope periodically. Now that the deep DMT scratches are worn away, I'll switch to regular light passes with slurry.

Thanks

I'm confused enough about how the OP worked through the grit/polishing progression that I'd hate to be tested on it, but isn't a good part of working 'up the ladder' the intention to spare using the coticule as much as possible?

I don't find the coticule inadequate (with slurry) as a cutter, even if you're sharpening something that's 'dull as a butterknife'. As long as it doesn't have a bad nick, the coticule will sharpen it, and promptly enough too. It does, however, wear away rock as well as metal.

I can't use a coticule without flinching if there's an alternative stone feasible. I often polish on a BBW with water, before going to the coticule with a light slurry. I don't have a fixed progression and sometimes use other stones pre-coticule, but all are pushed to the limit of fineness until the coticule is NECESSARY to improve the edge further.

I'm not sure I've learned much about coticules that way but it's helped improve my skills with BBW's and japanese stones.

I suppose I could spare the coticule more, but a) this one seems very hard and will not likely be even dented in my lifetime and b) I just like using it. If I can use the same stone for coarser work with slurry and finishing work with water, then all the better.

But, to each his own. I certainly understand where you are coming from. I would probably be singing a different tune with a soft coticule.