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Coticule Flattening - How Often


Well-Known Member
I just checked to see if my Coti was flat by using a pencil grid, and giving it a few circles, and it was perfectly flat! I was thinking it might need to be flattened, because I'd used it with slurry 'who knows how many' times. When raising a slurry, I try to rub evenly with the slurry stone by using this side to side motion working the length of the stone, and I give it a few extra rubs on the ends to account for dishing. I figure this helps to keep it flat.

I really don't think I'll need to lap this thing for a long time.

What are your guys' experience with this?

P.S. What are some good tests to check for flatness? Is checking for suction on a marble tile sufficient?
i have found when doing a lot of heavy work with slurry has slightly made mine uneven i just put mine on glass chopping board or kithchen top and push down on each corner and look for move ment or slight wobble then i lap with my dmtc it only takes a minute and flat again.
Lapping hones...

Whenever I read threads on other forums from rookies seeking advice after a not quite satisfactory honing job, there always -usually another rookie- popping the question: "Is your hone lapped?".

In my experience, it is an overstated non-issue. Some synthetic hones glaze with swarf, and they need to be cleaned by lapping, that much is true. Equally true is that a severely dished hone will not create the best possible edge. But it is not necessary to be anal about it. Ardennes, for instance, laps their hones to a visual degree of trueness. If you do the pencil grid test on them (draw a pencil grind on the surface of the hone and check if you can remove the entire grid with just a few lapping motions on a known flat abrasive surface), you'll find that Ardennes doesn't lap them that flat. I guarantee that it doesn't make any difference. I have honed razors on Coticules that were even visually slightly out of true, and there was no problem whatsoever getting excellent edges.

So, please don't waste precious Coticule by lapping your hone to mathematical flatness, every few razors.

What I do recommend are a few habits to keep your hone flat within reason during its entire lifetime. (Indeed, it may never require additional flattening):

1. While raising slurry, spend extra time on the far ends, notably the corners of the hone. Secondly, concentrate on the "high" spots. They can be identified because you'll feel less resistance rubbing over them. At the lower spots, the rubbing stone will suck itself to the hone.

2. If possible don't use the hone in the same direction during the regular slurry stage of honing. Once you arrive at the "refining" stages, do keep the stone oriented in the same direction. (You don't want slight variations introduced in you honing at that point)

A Coticule is not a synthetic hone, but I doubt even those need the kind of frequent lapping that you see often recommended. I am sure manufacturers don't object against customers lapping their hones through the sink...

When this thread has taken its course, I'm going to distill a FAQ article to put in "the Mine" section.

Best regards,
I rarely lap my natural stones, coticules and Eschers etcetera after the initial flattening. The synthetics OTOH I lap often. Especially the Naniwa superstones as within a honing session I get an amount of swarf that requires cleaning fairly often.

Last year on ebay I bought a razor and a coticule from a barber's son. His father had passed away some twenty years before and the son, now an old fellow himself, was finally selling off his father's tools.

The razor was an Engels Wedge and hadn't been touched since the old barber had honed it last. It was scary sharp and shaved wonderfully. The coticule is a 130x50mm yellow with a bbw glued to the underside. From the look of it I would suspect that the blue wasn't used at all.

The yellow was not flat. Upon drawing a pencil grid I found that the hone was more convex than concave. I have noticed this with Shapton pros, Naniwas and Nortons that I hone on. I draw the pencil grid and lap.

The center area is higher than the ends. I think this is because I use a bit of pressure on the heel and on the point at the beginning and at the end of the stroke going very light in the middle.

I had read about this technique in a 1961 barber manual excerpt on honing and practiced it. They recommend the technique to avoid creating a frown. So I think the barber must have honed that way and that explains the phenomenon of it being convex. I think that the X stroke enables the honer to get a keen edge even if the hone is not absolutely flat.

Another little experiment I did was with a long Swaty I bought on ebay. It was new old stock in the box with instructions. In the '80s I acquired some hones from old barbers and some lessons in using them. None of them ever mentioned flattening the stones. I doubt if they ever did.

So upon getting this long Swaty I checked it with a straight edge and it was far from flat. Being that it was new old stock I didn't have the heart to lap it. I put it away and forgot about it. Later I decided to try it after the 8k level to see if I could improve the edge in spite of the thing being far from flat and using the X stroke I was able to perceptibly improve the edge.

I spoke to Lynn Abrams on the phone about this and he agreed. He told me that in his early honing days some of the Nortons he wore out looked like a canoe before he learned of flattening the stones yet he was able to ge the razors shaving sharp. Not that I recommend honing on hones that are not flat but IME it is, as Bart says, not the be all and end all.
I had a feeling that flatness wasn't that big of a deal. I noticed that it wasn't flat when I first got it, and I figured it would be flat since Bart had honed on it, unless Ardennes had taken it to their wheel again before shipping it out. Cool, good to know. I doubt I'll ever lap this thing again, it made me cringe when I lapped it that one time. :-/

This reminds me of that thread over at SRP where they were discussing lapping their Nakayamas. I was thinking I wouldn't have the heart to lap them. Aren't they a really hard stone anyway? I think one guy (JimR maybe?) got his from a Japanese barber that made atom splitting edges, and that stone wasn't flat! I wondered why lapping was so pushed, when barbers back in the day used visually unflat Coticules, and could still get excellent edges.

Thanks guys, I don't want to be wasting any of this beauty!

JimmyHAD said:
I think that the X stroke enables the honer to get a keen edge even if the hone is not absolutely flat.
I believe that is a key statement. The X-stroke (and its derivatives) continuously shifts the points of contact that the edge makes with the surface of the hone. That both deals with variations in the straightness of the blade and with slight variations in the surface of a hone.

justin said:
(...)I figured it would be flat since Bart had honed on it (...)
:p I don't lap them as they come from Ardennes. It wouldn't make any significant difference for my tests. I am very sure of that.

I don't like to see slurry disappearing in the drain either...:cry:

Ah, don't worry about it Justin, that stone will outlive your grandchildren anyway.:)

The one i found in my barbers shop that was years old was very dished in the middle i no for a fact he never flatternd that one.
The two stones I got from my barber were both really, really trashed on top--like, scratches, trenches, chips...but yeah, the edges my BARBER got off them were topnotch. I haven't got there yet, but I'll confess, I lapped them. I was frankly afraid to use them in that condition. (My barber did, in fact, recommend I lap them...)

I, with Jimmy, feel better if I lap my Naniwas frequently, just because they really do get funky, fast. Maybe I should rethink that, though.
I have to lap the naniwas frequently only because they seem to fill up with swarf so fast. The blade then glides to easily on the surface to do any effective honing. The sae is true for the Shaptons, but they are not as sensitive as the Naniwas.

I'm glad to know that I'm not the only one that isn't anal about lapping. I've not touched mine since the initial lapping (any hones except to remove swarf on my Shaptons). This is great information!:thumbup:

Consider yourselves "Thanked" collectively;)
Well I checked mine last night and its like a banana! there must be a 1 to 2 mm curve in it, if I place it coti side down I can see light through the middle of it, and when I turn it over to the BBW side the ends are off the worktop! My god I have bent it!!!... lol
Don't try to straighten it with a vice, as some folks on this forum did with the razors. :lol:
I haven't lapped #23 yet, and probably won't for quite some time if ever... meh, edges are "butter"
A dozen or twenty 'laps' at the end of a sharpening session as part of the clean up is by now a regular part of my routine. The amount of lapping I do is as close to 'none' as I can manage, and the frequency is 'often'. I consider it minor maintenance and generally use a DMT 8000 to assure absolutely MINIMAL stone removal.

Occasionally I'll use two good hones and just rub them together, but in no case is significant stone removal desirable. The 'maintenance' laps don't make any obvious difference immediately, but they *prevent* dishing.

fwiw I find that chamfering the edges of hones is of much benefit; moreso if the hone is fairly narrow. One of the unexpected benefits of collecting stones is the opportunity to directly compare differing techniques and styles on the same rock, and the SAME style on different rocks. Comparison in action exposes any flaw or irregularity posthaste, and allows adjustments as needed. The wider the range of polishing stones I accumulate, the easier it is to appreciate each one for their unique feel. I have a largish Honsuita that I regularly buy (estate sale) vintage carbon steel knives for; and it's the SECOND best one.

I'm not good enough yet to justify putting the best one in rotation, I've only been practicing 47 years..and unfortunately, I didn't start STUDYING stones and techniques till a decade ago. Gimme another 15 years...
mitchshrader said:
A dozen or twenty 'laps' at the end of a sharpening session as part of the clean up is by now a regular part of my routine. The amount of lapping I do is as close to 'none' as I can manage, and the frequency is 'often'. I consider it minor maintenance and generally use a DMT 8000 to assure absolutely MINIMAL stone removal.
Beware of using fine DMT's such as the EE(8K), E(1.2K), and F(600grit) for lapping a Coticule. The garnets have a way of removing the bite of fine diamond particles. I wouldn't use anything above a DMT-C(325 grit) for lapping a Coticule, but even that one will wear prematurely from this practice. For serious lapping of Coticules, the DMT-XX (120 grit) is the best choice.

Note that for razor use, there's no need for frequent lapping of Coticules. Coticules don't glaze and and wear at very slow rate. If you raise slurry strategically, i.e. rubbing primarily at the corners and ends of the stone, 100+ razors can be honed from A to Z before the hone ever needs lapping, if at all. For chisels, gouges, and other tools that have a way of wearing transversal hollowing into a hone (as opposed to longitudinal hollowing caused by sharpening razors and knives, lapping needs to be done at slightly higher frequency.

It's my opinion that lapping serves mainly to remove embedded swarf (glazing). On a Coticule, that doesn't happen at all, so it's not a real issue. I don't recommend doing any lapping, unless you experience a noticeable decline in final keenness. By the time they encounter that occurrence for the first time, even new users should have gained enough experience to recognize such a decline, certainly on a razor's edge, that is incapable of bluffing its way through a shave. Coticules wear slow enough for that.

Best regards,
No arguments about 'need' as regards razors, my opinions are as yet unformed and will benefit from your experience.

I use stones from 'very soft' (blue aoto) to 'volcanic glass' (nearly, black/translucent arkansas) and the belgians are undoubtedly the most agressive.
The DMT plate I use on belgians is significantly worn, and it hasn't much use otherwise. The amount of 'lapping' that actually occurs would have to be measured with a micrometer, as several years worth of that habit hasn't yet caused noticeable wear. It is also significant that I buy stones regularly to increase the depth and range of the 'orchestra', which means that each stone may be in rotation 1/3-1/4 of the time, and otherwise parked.

Razors are as yet somewhat mysterious to me; I am not satisfied to stay ignorant. I have a 4/8 R. Droescher 'Gold Bug' that I want to put in service and am incompetent to do so.

Once I've figured out how to avoid ruining it, I'll be a much happier camper.

And if and when anyone stumbles over lower grit (than belgian) natural stones they're willing to mention, I'm hunting. European stones most desired..