GGs,

It seems when I strop an iron using a leather strop, it appears that
I'm dubbing the edge.  Instead, I've used a flat piece of pine and 
rubbed it with that green stuff - chromium oxide honing compound-
and I seem to do a lot better.  Is the leather strop better than the
method I'm using?  If so, what am I doing wrong?

Cheers, and thanks in advance,
Jack in Endwell, NY

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Jack asks about why he may be dubbing the edge using a leather strop...

Not seeing your technique, this is just a guess. Could it be that the 
curvature or belly that you have in your leather strop (belt?) creating 
this. Try glueing the leather to a firm/flat surface similar to the way you 
used the piece of pine, and use the smooth side of the leather. YMMV...

charles, North of Boston.
woke up to new frost this morning,
after digging out my shorts and T's last weekend. 

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>Jack asks about why he may be dubbing the edge using a leather
strop...<

"Leather" is a group of materials with very diverse properties. It
may be very hard and firm or very soft. If you use a soft strop, or
(as Charles said) don't have it glued down dead flat, it will tend to
round over the edge. And "soft" here is a range: most leathers that
you come across from miscellaneous sources will be quite soft for
this purpose. Even veg-tanned thick steerhide, my preferred strop
material, is softer than pine; sole leather is very hard, but perhaps
too hard. Most random-source leather is chrome tanned, and in my
opinion far too soft for strops. This is one reason I dislike the
any-old-scrap-will-do approach (the other is that worn leather from
odd sources may well have embedded grit or dirt that will injure the
edge--- it does not take much, and you might not notice the effect).

There are two stages in stropping as I was taught it. Both are
polishing, not metal-removal, steps. As a friend was told by her
jewelery teacher: "there are compounds for moving metal, and
compounds for removing metal". Polishing just moves the metal around.
The first part of stropping uses jewelers' rouge or some other
polishing compound on a carrier. The carrier may be very hard, like
an endgrain wood block, in which case you must hold the bevel at
exactly the right angle to get the right effect. It may be slightly
soft, like cardboard or flsh-side (rough-side) sole leather. Sole
leather goes through a pounding step to compress it, and may be
filled with waxes or other compoounds. Hard vegetable-tanned
steerhide, the material that weightlifters' or tool belts are usually
made of, is soft enough that it will give a bit under the edge and
you need not be quite so precise in the angle you hone at---  the
downside is that it may round over the edge just a hair. Anything
softer will round over the edge perceptibly and will cause problems.

The second step in stropping as I was taught it is using the hair
(smooth) side of leather without compound. Without this step
leatherworking knives will not cut sweetly. Most of 
what I said about the softness of leather as a carrier for rouge goes
here too, but a bit more illumination can be added. Instead of using
leather for the final polishing, you can use a steel--  a highly
polished steel rod. This must, like a wood compound-carrier, be used
at exactly the right angle, so it is not user friendly, but it moves
the metal surface around without removing any of it. Steels were
favored by meat cutters and butchers, and it is my belief that this
was because a leather strop would absorb body fluids and go rancid,
while a steel could be kept clean.

If stropping on leather does round over your edge and on wood doesn't
then probably your hand is doing the right thing (unless you aren't
getting the edge down onto the wood at all). In this case try a strop
made of harder leather. Shoemakers' suppliers will usually sell a
strip of sole leather about four inches wide; this is intended for
two shoe soles, and is just right for a strop.And make sure the wood
you glue it down to is flat, and that it is quarter-cut so that it
stays flat.

Tom Conroy
Berkeley

		
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  Great post Tom! It doesn't get any better than this one----I do
have to make one point on steels---

--- Thomas Conroy  wrote:
> Instead of using leather for the final polishing, you can use a
steel--  a highly polished steel rod. This must, like a wood
compound-carrier, be used at exactly the right angle, so it is not
user friendly, but it moves the metal surface around without removing
any of it. Steels were favored by meat cutters and butchers, and it
is my belief that this was because a leather strop would absorb body
fluids and go rancid, while a steel could be kept clean.

gilding the lily, gam sez:
  All this is true, Tom, but additionally, steels use a concentrated
force to form, harden and align the edge, creating sharpness by
drawing metal out to form a cutting point.  You could probably use a
steel on wood-cutting tools, if you used it on the bevelled side at
"exactly the right angle" but I wouldn't recommend it. On knives and
cleavers in the kitchen, it's an art, not a science, involving a
great deal of listening, intuition and angle-shifting. 
  Among chefs much is made of the magnetic properties of the
steel---most of the good steels are magnetized---and how this
magnetism aligns the domains of the molecules in the edge to lengthen
its life---like cryogenics (and prayer) it can't hurt, but the steel
itself whether "highly polished" (which is rare in my experience) or
ridged a little like a file (which is common, IME) basically
cold-forges a sharp and somewhat durable edge. You press the two
surfaces together pretty hard sometimes; it must translate to many
hundreds of lbs per square inch when you consider how small the point
of contact really is.........
                           GAM, turkey carver and Seattle resident
  

		
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______________________________________________________________

Jack Kamishlian wrote: "It seems when I strop an iron using a leather
strop, it appears that I'm dubbing the edge. Instead, I've used a flat
piece of pine and rubbed it with that green stuff - chromium oxide
honing compound-and I seem to do a lot better. Is the leather strop
better than the method I'm using? If so, what am I doing wrong?"



Jack, I strop in one of two ways. The first is similar to you own, that
is, I use the Veritas green rouge rubbed on MDF (Medium Density
Fibreboard, Jeff). I find that the MDF is flat, hard, and yet porous
enough to hold the rouge. I always keep a 6"x 6" square handy.

The other method is best said in a whisper here, that is, I have a
powered Honing Plate" on a large belt sander that I modified for use
in grinding blades. The honing plate uses two sanding disks glued
front-to-front and attached with velcro. Veritas green rouge is
applied to the outer velcro surface. OK, I should not feel so guilty
about mentioning it here. Brent Beach has plugged it on his website
and there is enough talk of powered grinders thrown around. My main
interest is hand tooling and this is aimed at the restoration end of
blades (my sharpening is done on waterstones). But it works damn well
and anyone thinking of a powered bench grinder should look at a belt
sander instead.

Picture of belt sander:

http://www.woodworkforums.ubeaut.com.au/attachment.php?attachmentid

Picture of Honing Plate:

http://www.woodworkforums.ubeaut.com.au/attachment.php?attachmentid

Now my main reason for replying to this topic was to discuss the whole
idea of stropping. Brent has some rather negative things to say on his
website, and his evidence is strong.

See:

http://www3.telus.net/BrentBeach/Stropping/Stropping.html

In a recent email conversation with Brent, he made the following points,
which I shall share with all (since I am sure that he would welcome
further discussion):

Derek: Firstly, if I understand you correctly, you are saying that all
honing degrades the sharpened edge. If so, why is it that the Veritas
green rouge seems to make a positive difference in practise? And why is
it able to remove scratches from a 6000 grit waterstone? What grit is
the Veritas green?

Brent: I have added a conclusion section to the stropping page (not
honing, a term I reserve for the use of fine abrasives on micro bevels).

I don't know why many people report improved results with stropping.
There are two likely answers.

First, they are starting with bevels that are much worse than mine. I
have done tests where I stop after the 5 micron abrasive and the blades
work, just not as well. Certainly if you go to 0.5 micron 3M
microfinishing abrasives then stropping is a mistake.

Second, perhaps done in a different way - saw on leather or using a
powered wheel - the results are different. It would be interesting to
put a few blades under the microscope - say one blade pre-stropping and
a second comparable blade post stropping - and see what the difference
is. To do this I would have to replicate a happy stropper's setup and
practise, or ship blades back and forth.

Removing scratches is a different problem. What you see - with the naked
eye I presume - when you think scratches are being removed is not
necessarily that. It could simply be a different kind of scratch. The
6000 grit stone may contain a variety of grit sizes - most do, even
artificial. The larger bits might be putting a scratch on the bevel that
you see as scratches, while all the small bits are putting on smaller
scratches which you don't see. The strop may be changing the scratch
size distribution in a way that looks like the scratches are gone.

Even with the microscope, the 0.5 micron bevels still have scratches.
However, they are fine enough that visible light is not reflected in a
way that makes them visible.

Derek: Secondly, is there a paste/rouge/other that I can use on my
Honing Plate that will enhance the honing process (diamond? If so, in
what medium?)


Brent: I have read that there are green crayons - CrO - that are almost
pure CrO. Lee Valley, at least back when I bought mine, was a mixture to
improve cutting speed. The pure CrO will be slower and should only be
used on a micro bevel to get reasonable honing time. I don't know who
makes or sells the purer kinds.

Diamonds are fast, but test done by others and viewed under a microscope
show the same spread of grit sizes and scratch sizes (again, not all 0.5
micron diamond pastes, but those tested). Some suggest that diamond is
too hard for edge tools. Where softer abrasives split, diamond fractures
the edge more deeply. Again, powered strops or different strop material
may make a difference.

The bottom line for me is that I don't think strops work, but they
might. What I know does work is 3M microfinishing abrasives. I am
testing some oil stones these days and I will know something about them
in the next few months. I have some diamond paste and will try it in the
next month or so. 

Hoping that this fosters further discussion ...

Regards from Perth

Derek

p.s.   For all those in Perth, I shall be hosting a sharpening workshop
       on the 21st or 28th May (to be finalised). Contact me if you want
       to join in. No charge - just a get together for galoots in Perth.
       Bring your sharpest blades for comparison, your sharpest wit for
       communication, and your dullest blades for correction!!!!!!!

______________________________________________________________

>   Among chefs much is made of the magnetic properties of the
> steel---most of the good steels are magnetized---and how this
> magnetism aligns the domains of the molecules in the edge to lengthen
> its life---like cryogenics (and prayer) it can't hurt, but the steel
> itself whether "highly polished" (which is rare in my experience) or
> ridged a little like a file (which is common, IME) basically
> cold-forges a sharp and somewhat durable edge. 

I think the longitudinal file-like ridges act more like file teeth and 
the magnetism is there to keep the filings from falling onto your 
turkey. I keep our kitchen knives sharp with a smooth steel -- they 
haven't been abraded in years. Try your burnisher in the kitchen -- 
you'll love it. (And you can sharpen scissors, too, with it. Just close 
the scissors on the burnisher like you were trying to cut it in two. Run 
the rod up and down the length of the blades. Works.)

The Rev.

-- 
Ron Hock
HOCK TOOLS  http://www.hocktools.com
16650 Mitchell Creek Dr
Fort Bragg, CA  95437
(707) 964-2782 fax (707) 964-7816

______________________________________________________________

:  -----Original Message-----
:  From: Jack Kamishlian [mailto:kamishlian@g...]
:  Sent: 13 April 2005 00:05
:  To: oldtools
:  Subject: [oldtools] Stropping

:  It seems when I strop an iron using a leather strop, it appears that
:  I'm dubbing the edge.  Instead, I've used a flat piece of pine and
:  rubbed it with that green stuff - chromium oxide honing compound-
:  and I seem to do a lot better.  Is the leather strop better than the
:  method I'm using?  If so, what am I doing wrong?

Not exactly wrong, but is is really necessary to strop an 'iron' (ie a plane
iron. Under planing conditions, many repetitions at speed against much
resistance will soon break down a fastidiously sharpened edge.

Stropping is perhaps best kept for carving tools (and bookbinders tools of
course)?

For microbevel sharpening using chromium polish on a glass plate people
might like to look at my web site - Sharpening Notes -  Some Scientific
Light on Sharpening Technique.

Jeff

-- 
Jeff Gorman, West Yorkshire, UK
www.amgron.clara.net

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