Touchup/Re-sharpening of a Razor

Zot! · Post by **Zot!** » Wed Apr 13, 2011 6:49 am

I have some questions about touching up a razor with a coticule. I have been experimenting with one when I get the chance, which isn't that often. I am not ready to try the unicot or dullicot re-honing after breadknife I read about on the coticule.be site yet.

I have read that using a coticule with slurry will have the effect of dulling a razor's edge, which I have experienced. My dvd from Lynn shows him using a coticule with a really light slurry to finish off a Norton 4k/8k hone. Is that edge really an 8k edge that has been made more comfortable but not any keener from the coticule?

Below, I have linked a video from Rasurpur of a re-sharpneing using a coticule (wow, its big!) and Naniwa 10k. It looks like the coticule and Nani are used with slurry and not much diluting or use of plain water. Is he using the coticule to do the heavy work and then the Nani to make a keen edge? Would a Nani 12k have done the same finish? What do you think of this video?

http://www.youtube.com/user/rasurpur#p/ ... Xr3JJlQrjc

matt321 · Post by **matt321** » Wed Apr 13, 2011 10:52 am

Yes, I've watched that one before. I thought it was interesting because the stroke style is unconventional. Also, the deliberate use of slurry on the Nani10K. I have two razors that I bought from him, and they were both very sharp when I received them.

Right, he seems to use the Coti for coarse work and then finish on the 10K.

I have both the 10K and 12K Nani's and I haven't noticed any advantage of one to the other.

I also have a Coti but I haven't had success yet with Dilucot or Unicot. Still working on that. Plenty of info over at coticule.be though.

matt321 · Post by **matt321** » Sun Apr 17, 2011 6:08 am

Decided to touchup the razor I've been using for about the last 10 shaves. It was still OK, but I thought I would try for a better edge. I started at 8k by the touchup rule..start one level coarser than the finish. (Some suggest starting two levels down as in "Drop 2 and Go".) After two sets of 10 half strokes on each side I could feel suction so I did one more set with light pressure and set the 8k aside. Did the same process on the 10k but did not get the suction, maybe because the 10k Naniwa is rarely as flat as the 8k (Shapton GS). I ended with the "3-2-1" method. Afterwards I added about 20 trips on a CrO loaded hanging strop. The razor felt sharp when tested on arm hair so I'll test shave this morning and report back.

"Halfstrokes" =
http://www.coticule.be/strokes.html

Glen's "Drop 2 and Go" and "3-2-1 method" =
http://www.shavemyface.com/forum/viewtopic.php?t=46242

Zot! · Post by **Zot!** » Tue Apr 19, 2011 4:41 am

Thanks Matt!

matt321 · Post by **matt321** » Sun Apr 24, 2011 5:47 pm

matt321 wrote:.... The razor felt sharp when tested on arm hair so I'll test shave this morning and report back.

I've shaved with this refreshed edge for a week now. I'd say it is a very good edge, still going strong. Probably better than my average refreshed edge. l hadn't used finger weighted half strokes before, but they must have helped in this case.

Maybe a new theory here (for me anyway) ...specific hone and razor combinations have an optimum pressure that is not necessarily the lightest possible. Lighter or heavier than optimum pressure leads to burring so that the bevel intersection is not optimum.

asharperrazor · Post by **asharperrazor** » Fri May 06, 2011 8:30 pm

Interesting theory. Possibly true.

If you use too little pressure, the edge probably isn't even contacting the hone, and if it is, you'd just be removing less material than ideal. Plus you run the risk of uneven honing, ie one part of the edge is in contact with the stone while another part isn't.

matt321 · Post by **matt321** » Sat May 07, 2011 5:49 pm

I've read posts on forums where the poster says he took a sharp razor and made a few passes to test some new finishing hone and now the razor is dull. I've had the same thing happen to me as well. Take a razor with a good shaving edge and run it over a hone and sometimes the edge will degrade.

So I figure there are other variables in play such as pressure on the hone. If all the factors are not optimum then the hone can degrade the edge slightly.

SmallTank · Post by **SmallTank** » Sat May 07, 2011 5:53 pm

get some Co...green paste..little bit goes a long way..goes on your 2nd strop..canvas..go 1 dozen times helps alot..if that doesnt help..re honing is needed

ST

Utopian · Post by **Utopian** » Sun May 15, 2011 4:09 pm

matt321 wrote: Maybe a new theory here (for me anyway) ...specific hone and razor combinations have an optimum pressure that is not necessarily the lightest possible. Lighter or heavier than optimum pressure leads to burring so that the bevel intersection is not optimum.

I'm sorry, I don't understand your logic. How would lighter than optimum pressure lead to burring?

matt321 · Post by **matt321** » Sun May 15, 2011 9:07 pm

Utopian wrote: I'm sorry, I don't understand your logic. How would lighter than optimum pressure lead to burring?

The hone acts primarily to remove steel from each bevel face. However, there are secondary compression forces which act on the extreme edge. Compression of the edge can result from friction along the bevel face or even from direct impact of the extreme edge with grit. Honing pressure has an effect on these mechanisms. If the pressure is too light, then the compressive forces predominate. In other words, if you use too little pressure the hone quits shearing the bevel face but continues to blunt the extreme edge.

The burr would look like the upper right diagram in this figure from Verhoven:

matt321 · Post by **matt321** » Sun May 15, 2011 9:15 pm

I should add that I got this from posts by other folks. I did not originate, but I am beginning to see merit.

The beauty of this model is it expalins why a few "very light" laps on a finishing hone can sometimes degrade the edge.

We've all seen this logic:
I got a sharp edge by finishing with hone "A".
Then I made a few light laps on hone "B" for testing purposes.
Now the edge is dull, so hone "A" is better than hone "B".

The pressure theory suggests this type of "one shot" test is an over simplification.

SliceOfLife · Post by **SliceOfLife** » Sun May 15, 2011 9:28 pm

Zot! wrote: I have read that using a coticule with slurry will have the effect of dulling a razor's edge, which I have experienced. My dvd from Lynn shows him using a coticule with a really light slurry to finish off a Norton 4k/8k hone. Is that edge really an 8k edge that has been made more comfortable but not any keener from the coticule?

No. Coti edges are sharper than Norton 8k edge. Quite a bit sharper in fact. I believe a big part of the problem is that Ardennes advertises coticules as ~8k grit. I don't know if they specify a scale. But even if that's JIS, that's a little below what my testing places them at. Anyway, some people took this number and ran with it. Sadly it's nowhere close to accurate for our purposes.

Gssixgun · Post by **Gssixgun** » Fri May 20, 2011 2:10 pm

Pressure is one of the hardest things to describe for honing because everyone keeps saying Light or Blade Weight...

Use just enough pressure to keep the edge even and evenly in contact with the hone during the stroke and no less

for finishing stroke...

matt321 · Post by **matt321** » Fri May 20, 2011 4:11 pm

More conjecture and musings on the subject:

Three possibilities for a freshly honed edge that shaves poorly.
1. Insufficient coarse honing, i.e. the bevel faces do not intersect.
2. Insufficient polishing, i.e. the bevel faces intersect but with coarse grind marks.
3. Fully formed bevel, fully polished, but degraded by burring.

By Verhovens definition all intersecting edge bevels are burred to some degree. The sharpest edges are burred the least.

Referring to Verhoven's diagram above, I suspect "edge burs" occur with too little pressure and "fold over burs" occur with too much pressure.

SliceOfLife · Post by **SliceOfLife** » Fri May 20, 2011 6:23 pm

In my experience, you need a 4. microscopic pitting.

I've gotten "shave ready" blades that were edged (cut hair fine), polished (usually up to 12k or higher) and looked visually perfect but gave a pretty crappy shave. A quick look under the scope and the edge had so many gaps from pitting that sections of it could be confused for a 500-4000 grit finish, despite the bevel being polished. People don't seem to realize that scratch patterns in the bevel hide pitting that doesn't "punch out" until you thin the edge on higher grits. I'd wager that quite a few guys out there shave daily with some pretty rough edges thinking they're using a 12k or 0.5micron or Asagi blahblahblah finish. It's gotten to the point where I check every eBay special on a scope AFTER honing before I'll shave with it. If I see any holes in the bevel or gaps or frayed metal in the edge, I push the edge back a mm or two and rehone.

matt321 · Post by **matt321** » Thu May 26, 2011 9:32 am

matt321 wrote:More conjecture and musings on the subject:

Three possibilities for a freshly honed edge that shaves poorly.
1. Insufficient coarse honing, i.e. the bevel faces do not intersect.
2. Insufficient polishing, i.e. the bevel faces intersect but with coarse grind marks.
3. Fully formed bevel, fully polished, but degraded by burring.

I think I spend most of my honing time in "zone" 3 with a fully formed and polished bevel and I'm trying to get a clean edge with minimal burring.

Knife sharpeners have various strategies for dealing with burs. One method is to progress thru finer and finer grit hones so that the bur becomes smaller at each level. Another method is to use light pressure to sweep away the bur without shearing up more. Also, changes in honing angle and changes in the stroke pattern or direction can destabilize a bur. Razor honing is unique, but I see parallels.

matt321 · Post by **matt321** » Sun May 29, 2011 5:29 am

matt321 wrote: I think I spend most of my honing time in "zone" 3 with a fully formed and polished bevel and I'm trying to get a clean edge with minimal burring.

Well, not more honing time, since it may just be a dozen strokes or so. I meant to say more time testing or experimenting.

Post by **drmoss_ca** » Sun May 29, 2011 7:11 am

One reads again and again of the importance of good stropping, and an awareness of secular trends in my stropping habits happens to be relevant. When you do something day in and day out, you slowly become aware of differences of outcome over the long term. I recently started re-using many of my old strops, just for variety. Like everyone else I gravitated towards the seemingly luxurious wide strops from Tony Miller, SRD and HandAmerican. Then I moved to paddle strops and found them good. But now I have gone back to narrower hanging strops after using them again. They are far less prone to curving from side to side than the wider strops, and it is easy to use a form of X-pattern when stropping to ensure the whole edge receives attention. Stropping makes all the difference to the tiny burrs referred to in this thread. A theoretically perfect honer will get one good shave from his newly honed razor, but what of the next shave? He needs a strop to minimise the damage done to the edge from that shave. Now I am not a perfect honer, not even theoretically. Long ago I found that a rough strop had some value before the finishing strop, and to give our forebears the credit of experience, that is why there is a canvas/linen strop on the back of the leather. But I found the reverse side of the leather useful, and have employed the Illinois #827 for this. I still use two of them for pastes (CrO2 and Flexcut Gold), but also have a plain one. Currently I am getting the smoothest shaves ever from 25 round trips on an 827 followed by 25 more on a Dovo Red Russian 2.5". I use 25 more after the shave on the canvas side of the latter strop. I continue to be amazed at how the traditional way of doing things has benefits (Duh! There's a reason why they learnt to do it that way!), and how I am still learning. I suspect that if I ever reach perfection - fat chance - I will then grow a beard instead to prevent boredom.

Chris

brothers · Post by **brothers** » Sun May 29, 2011 11:18 am

Eventually hitting on the right strops makes a big difference. After laps on the canvas, at the present time I use both sides of the Martin J. Rubin Horsehide, cleaned and conditiioned with a mixture of saddle soap and Neatsfoot Compound. Finishing of course, on the smooth side. The razors seem to be holding their edges and the shaves seem to be getting smoother. I hope I have enough sense to realize I should not change anything as long as what I'm doing seems to be working better than expected. (Knock on wood!)

Zot! · Post by **Zot!** » Sun Jun 05, 2011 8:53 am

I did some touch-up/experimenting with my three straights today. One of the problems with this is that you have to wait so long between touchups! This post is just to help me remember the what and when.

Cranford 5/8 half hollow
10 passes on Coticule with a light slurry (treating it as an 8k)
10 passes on Naniwa 12k
10 passes on .5 micron CrO bench

Dovo Best 5/8 full hollow
10 passes on Norton 8k
80 passes on Chinese 12k
10 passes on .5 micron CrO bench

Dovo Silver Steel 5/8 full hollow
10 passes on Coticule with a light slurry (treating it as an 8k)
50 passes on Coticule with water only (treating it as a 12k finisher)
10 passes on .5 micron CrO bench

After each of the above, stropped with SRD modular paddle using both x and straight strokes
60 passes on hard pressed wool pad
60 passes on English Bridle IV leather pad

SMF

Touchup/Re-sharpening of a Razor

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