Thread: Burnishing a coticule stone

I've just got my stone today, And I've been playing with it all morning.

It looks similar to KenG's. Probably the same vein.

Out of the box it was very rough to hone on. Felt like marbles or grit with slurry, So I lapped it out with a 400 diamond plate and tested again. It still had the rough feel. So I lapped it again to 1K.

It's an odd rock. I've put 3 razors over it. The original 1K razor came off the rock sharp cutting arm hair and after stropping a reasonable HHT3-4, The second one took a lot longer to get it to feel right on the rock, and came away with an edge that refused to cut arm hair, After stropping this went into a really solid HHT4.

The last razor well I didn't use slurry on the second razor, And by the time I got to this 3rd razor the rock is so slow I can't see any material been removed in the water. I did about an hours worth of honing. Off the rock the razor refused to cut arm hair again. After stropping the edge is like lighting. HHT5 for most of the blade (the toe is at a 4). The stone has taken a glass like polish and feels like my arky when honing. No idea what the shave will be like but I'll get to test it later.

The burnish after that 3rd razor is mirror like. It's even reflecting colour. I need to do full shave tests to see what the rock puts on the edge but so far the burnished finish looks slow but very promising. My worry is that edge doesn't feel like a coticule edge.

Nice, yes it has the wood grain look like mine. Also, I keep looking at the slate on the back- it has beveled edges and an 'ink blot' pattern. I've read its not recommended for razors, but, dang it I have to try just to satisfy my curiosity. I'm going to the beach for a week in May and this stone is coming with. I mean, need something fun to do before the Lady gets up...

the slate side is exceedingly smooth to the touch and makes a white slurry. Haven't tried it on razor yet but I will. The mottled pattern on the slate matches the slate on the slurry stone that came with it, and the coti side has red streak.

None of my coticules have a slate backing, but it is my impression that it is not of much use for honing. Please let us know how it works for you.

What's on the back of"My Coti,s" ? Tc

Originally Posted by tcrideshd

What's on the back of"My Coti,s" ? Tc

Older coticules, and some of the new ones, are backed with BBW (Big Beautiful ...just kidding! It's Belgian Blue Whetstone). That BBW can be naturally adjacent to the yellow coticule layer and is cut to leave those layers together. These are considered to be natural combination coticules. The majority of mine are of that type. I believe that both of "your" coticules are of that type. Certainly the thicker one is but I don't recall the other one.

Alternatively the BBW can be glued to the yellow coticule layer. The reason that the BBW is glued to, or left attached to, the coticule layer is that it provides strength or support to the relatively fragile coticule.

Many modern (recently mined) coticules are backed by slate. It is there for support only and is not considered to be of use for honing, but your results may vary.

Originally Posted by Utopian

Older coticules, and some of the new ones, are backed with BBW (Big Beautiful ...just kidding! It's Belgian Blue Whetstone). That BBW can be naturally adjacent to the yellow coticule layer and is cut to leave those layers together. These are considered to be natural combination coticules. The majority of mine are of that type. I believe that both of "your" coticules are of that type. Certainly the thicker one is but I don't recall the other one.

Alternatively the BBW can be glued to the yellow coticule layer. The reason that the BBW is glued to, or left attached to, the coticule layer is that it provides strength or support to the relatively fragile coticule.

Many modern (recently mined) coticules are backed by slate. It is there for support only and is not considered to be of use for honing, but your results may vary.

Very good summary on bbw and coticule backing. I will add a lot of people would want a coticule backed with a bbw. Its nice to have a combination stone. This is why most combination coticules you buy directly from the mine or a place that does resales cost a lot more then the portugese slate backed coticules. A coticule found in the wild will most likely be backed with bbw. People tend to hold on to their recently purchased stones or they end up on ebay. Not in the wild.

Many before have tried to use that portugese slate for honing and didn't find any use for it. If I were you I would try it but you're not going to have any luck convincing the community that portugese slate is the next "one stone" solution.

Originally Posted by Iceni

I've just got my stone today, And I've been playing with it all morning.

It looks similar to KenG's. Probably the same vein.

Out of the box it was very rough to hone on. Felt like marbles or grit with slurry, So I lapped it out with a 400 diamond plate and tested again. It still had the rough feel. So I lapped it again to 1K.

It's an odd rock. I've put 3 razors over it. The original 1K razor came off the rock sharp cutting arm hair and after stropping a reasonable HHT3-4, The second one took a lot longer to get it to feel right on the rock, and came away with an edge that refused to cut arm hair, After stropping this went into a really solid HHT4.

The last razor well I didn't use slurry on the second razor, And by the time I got to this 3rd razor the rock is so slow I can't see any material been removed in the water. I did about an hours worth of honing. Off the rock the razor refused to cut arm hair again. After stropping the edge is like lighting. HHT5 for most of the blade (the toe is at a 4). The stone has taken a glass like polish and feels like my arky when honing. No idea what the shave will be like but I'll get to test it later.

The burnish after that 3rd razor is mirror like. It's even reflecting colour. I need to do full shave tests to see what the rock puts on the edge but so far the burnished finish looks slow but very promising. My worry is that edge doesn't feel like a coticule edge.

BUMP.

So what happened?

I'm still learning it. And still getting different edges depending on how much polish I put into the rock.

It seems to function best when finished to the highest level I can get it to. And using a finished razor (12K). Then build the lightest slurry with the slate side of my rubbing stone or a glass block. Doing this the edge is pretty much always fantastic. It's still coming off the rock feeling like there is no edge, and after stropping it's going right up to a level of sharpness in the HHT 4 region. I have most of my razor rotation finished like this now so it's providing me with edges that I think are really nice. Soft edges that you can't feel on the skin, They don't shave to BBS without a 4th pass but on a 2-3 pass shave they provide a totally irritation free DFS. Slapping up my face with aftershave after a pat down with one of these edges and there is no sting unless you hit a weeper. All of my coticule edges have been finished like this at this time, After a few shaves and a few refreshes with crox these edges are getting better and better my Bismarck 7/8 is currently on a HHT 5 and the edge is so soft it's insane.

Using the coti side of the rubbing stone removes the polish of my stone finish and the combination of both veins is fast but inconsistent. I can only assume that there is some coticule voodoo working there. Perhaps the garnet sizes and rock hardness differences and working against each other. My rubbing stone is defiantly softer and from another vein. The edges with the combination slurry are still there but depending on the razor I get some nice edges that feel sharp, and others that just don't feel right at all. Hence I don't use the combination slurry now. Getting that buttery feeling is just not happening for me with this method. The edges all feel sharp but not as good as a thuri edge.

Using a diamond plate (1K) to raise slurry I find that I have to work the stone a lot longer on the thinning stages. There is a point with this method where the slurry is gone, but the edge isn't quite there. Adding more slurry with the diamond plate puts you right back at that point and to get past it takes a lot of strokes removing very little to get that sticky feeling. Once you get to that stage the edges are good but sometimes inconsistent. The extra time on the hone and the fact I'm using a razor to add polish to the rock is probably the fault. I had one razor like this that felt like it had 2 edges. The heel felt buttery sharp, the toe felt regular sharp! Others have come off with an edge that feels like the Neutral block edge all over. Other edges have come away feeling like a regular sharp edge with no buttery feeling. The extra time to hone and the inconsistency is why I don't do this one any more.

I've tried to use the stone from a 1K, 5K, 8K, and 12K finish. The best results for me have all come from a 12K finished razor using the neutral block slurry on a rock that is well polished. When I try to use my stone for anything lower than 8K I find it'll work provided the slurry is there, but getting it to drive past that stage where the slurry has died and you want the edge to come in all sticky just takes far too long and allows the stone to be inconsistent. As such I'm using my rock is a finishing only coti. I've not tried a touch up with it yet on a razor that has been shaving and needs a refresh. I may find I have to take it back to 5K then through to 12K again as it may not have the cutting power to refresh without the minor reset. Every razor that has been finished like this seems to be getting better with use. So perhaps I need more Crox from the off to see if I can make an edge perform as well from the start.


I'm sure in 6 months time It'll all be different again! For the minute I like my polished coti a lot.

Interesting read Iceni. A lot of data collection there. Do you have a lot of razors or are you just honing these three very often?