Thread: Why is the 1st shave after honing so disagreeable?

Originally Posted by Bart

Actually, Verhoeven is were I got most of the information I wrote about in my previous post.
http://www.bushcraftuk.com/downloads...nifeshexps.pdf

But whatever the explanation, that a "pull-honed" edge is weaker, is something that can easily be backed by empirical evidence: I believe many people can confirm that from their own experience.

Best regards,

Bart.

I read the paper in your link and I didn't find anything that supports your point. Maybe you could quote if for me. What I did find was this:

The major conclusion of the study is that of the three honing methods studied, the best method for removing the bur and setting the edge angle is clearly a final polish on leather loaded with a polishing compound such as the chromium oxide or diamond compounds used here.

Esteemed colleageus and research associates,

OK, so here is a thread about my new razor: Wustof 5/8

I have pics of the edge at 200x coming right off the 1um diamond lapping film (honed straight up and down, dry).

Then the same edge after 15 laps on a lightly coated chrome ox hanging strop (stropped at an angle)
and then stropped on new TM "smooth" cavas and latigo (straight up and down, as it is a 3" strop, I also mistakenly called it "linen" for some sleep deprived reason...? It's truly canvas).

As can be seen, the bevel has been rounded/smoothed out significantly, and striations are visible in a diagonal direction.

So, the abrasion was carried out by the chrome ox (as per the diagonal striations), and there is little or no visual evidence of what the subsequent canvas and latigo stropping did to the edge. However, perhaps they contribute to simply smoothing out the striations that are there.

As I stated in that post, next time I'll skip the chrome ox and see what canvas and latigo do by themselves.

Nice thread & discussion, thanks guys!

Originally Posted by Seraphim

Esteemed colleageus and research associates,

OK, so here is a thread about my new razor: Wustof 5/8

I have pics of the edge at 200x coming right off the 1um diamond lapping film (honed straight up and down, dry).

Then the same edge after 15 laps on a lightly coated chrome ox hanging strop (stropped at an angle)
and then stropped on new TM "smooth" cavas and latigo (straight up and down, as it is a 3" strop, I also mistakenly called it "linen" for some sleep deprived reason...? It's truly canvas).

As can be seen, the bevel has been rounded/smoothed out significantly, and striations are visible in a diagonal direction.

So, the abrasion was carried out by the chrome ox (as per the diagonal striations), and there is little or no visual evidence of what the subsequent canvas and latigo stropping did to the edge. However, perhaps they contribute to simply smoothing out the striations that are there.

As I stated in that post, next time I'll skip the chrome ox and see what canvas and latigo do by themselves.

Nice thread & discussion, thanks guys!

Nice pictures. I can clearly see that irregularities in the honed edge (almost look like tiny chips) are nearly all smoothed out. I can't quite decide whether the rounding over effect is essentially reducing the angle
or is it just thinning it out. eventually though it would seem to lead to less supportive material at the near edge steel.
__

Plastic flow = bending that I can understand. The monkey wrench effect of sharpening razors lies for me at least in their extreme flexibility. I feel myself using too much pressure while stropping yet appear powerless to stop. I sure have lightened up on the hones, though still I may be a bit heavy.

I think in back stropping on paste there would be far less material to be deposited as compared to 8g stone. I wonder how much effect or difference there is back honing wet vs dry

fwiw In the experiments on flat hones the blade was flipped and the opposite face honed 1/1 pass on each face.

Originally Posted by Chimensch

I read the paper in your link and I didn't find anything that supports your point.

QUOTE: "It seems likely to this author that two mechanisms
give rise to bur formation along the edge during sharpening.
(1) Debris Deposit The polishing and grinding on the
metal faces of a knife blade during sharpening produces an
abrasive polishing action. One may think of this action as
like having thousands of little ploughs (abrasive particles)
that move along the surface pushing scraped up metal, debris,
in front of them. If the abrasion direction is away-from the
edge, direction A of Fig. 3, then the debris will be deposited
along the edge on the face opposite the face being abraded. If the abrasion direction is
into the edge, direction I of Fig. 3, one would not expect debris pile-up along the edge as
now it is being pushed away from the edge. However, as will be shown later, debris does
collect at the edge for abrasion in the I direction, although to a reduced extent. There
must be a subtle mechanism of debris deposit along the edge, perhaps involving some
type of back eddies at the edge.
(2) Bending The width of the blade at the edge and just behind it is extremely thin.
Hence the force against the edge from the abrasive media will result in large stresses,
force per area, at the edge, which can lead to plastic flow (bending) of the edge region.
(Note: The small bumps running parallel to the edge, such as the two labeled bending flow in the Up face
of Fig. 1, result from a small bending flow of the edge region away from your view.)
The combination of the bent edge and the collected debris forms a bur on the side of the
edge located away from the abrading media. (Some authors [1] call this deformed edge and
accumulated metal debris a "wire", but the term bur will be used here.) Burs
that fold around the edge can be called fold-over burs and they
have a variety of shapes with two examples shown in Fig. 2(B).
The edge burs of Fig. 2(A) show little bur material and appear to
be edges that have simply been rounded during sharpening.
However, such edges will be termed "edge burs" here to indicate
a type of edge formed in sharpening that differs from a fold-over
bur." END OF QUOTE

Originally Posted by Chimensch

Maybe you could quote if for me. What I did find was this:

The major conclusion of the study is that of the three honing methods studied, the best method for removing the bur and setting the edge angle is clearly a final polish on leather loaded with a polishing compound such as the chromium oxide or diamond compounds used here.

Verhoevens paper is largely focused on regular knife sharpening, where one deliberately hones one side of the knife until a bur is raised raised, then hones the other side till the bur is raised on the opposing side and finally removes that bur. We all know that razors are sharpened differently, but still Verhoeven's paper offers valuable information about what happens at the surface of an edge during honing.

Apart from that, I own a Tormek sharpening machine, and use that a lot for sharpening various woodworking tools. On a Tormek you can choose whether the wheel turns into the edge or away from the edge. Regardless the method it's very easy to make a plane blade shave hair on a Tormek. But when honed with the wheel turning away from the edge, a blade dulls much sooner. Similar results I get when honing a razor on pasted strops. Keeness is excellent, but durability is not.

Bart.

Originally Posted by Bart

Verhoevens paper is largely focused on regular knife sharpening, where one deliberately hones one side of the knife until a bur is raised raised, then hones the other side till the bur is raised on the opposing side and finally removes that bur. We all know that razors are sharpened differently, but still Verhoeven's paper offers valuable information about what happens at the surface of an edge during honing.

Apart from that, I own a Tormek sharpening machine, and use that a lot for sharpening various woodworking tools. On a Tormek you can choose whether the wheel turns into the edge or away from the edge. Regardless the method it's very easy to make a plane blade shave hair on a Tormek. But when honed with the wheel turning away from the edge, a blade dulls much sooner. Similar results I get when honing a razor on pasted strops. Keeness is excellent, but durability is not.

Bart.

But, in effect, when honing a razor we use both methods. Towards the blade with the hone and then away to smooth with abrasive paste. You seem to be saying that one should only use an increasingly fine series of hones and never paste. I don't see anything wrong with setting the bevel with a hone and then smoothing with paste. This would seem to be the best of both worlds, according to Verhoven. In other words, you seem to be making it an either/or and I don't think that's the conclusion that Verhoven would have made.

Originally Posted by Chimensch

But, in effect, when honing a razor we use both methods. Towards the blade with the hone and then away to smooth with abrasive paste. You seem to be saying that one should only use an increasingly fine series of hones and never paste. I don't see anything wrong with setting the bevel with a hone and then smoothing with paste. This would seem to be the best of both worlds, according to Verhoven. In other words, you seem to be making it an either/or and I don't think that's the conclusion that Verhoven would have made.

I'm not speaking in favor of either of both methods. I'm only saying that an edge that's the result of pull-honing is less durable. Not that it is less sharp, or less suitable for shaving. Verhoeven recommends a pasted strop for bur removal. For sharpening razors, the idea is that one doesn't need the remove any bur. Johnny's method with the exclusive use of barber hones is a bit of an exception to that rule, but even in that case, it seems to be better to remove the wire edge (bur) by backhoning a few strokes and then proceed with a few final normal strokes. If you'd use the knife method on a razor by deliberately raising a bur and removing it with a CrO strop, you'd get what Johnny had when he started this thread: an fine shaving edge that needs very frequent touch-ups.
I'm convinced there are other methods yielding better results, but I'm NOT saying people should stay away from pastes. I'm only convinced that it decreases the "mean time before honing" to some extent.

Best regards,
Bart.