Stropping; At My Wits End!!

Lenny

Lenny

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Oct 15, 1998
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Everybody Else: "I strop my knife after using and it comes back to hair whittling sharp"
Me: "I strop my knife after using and it can't slice through butter" (a little exaggeration but you get the point)

So, I have 2 strops, one loaded with green compound, one double sided with both green and grey compound. Regardless of how I strop, the edge is duller afterwards. I've tried different angles, but always use just the weight of the blade on the strop.
What am I doing wrong?
 
At the risk of stating the obvious........What are you sharpening, what does the edge geometry look like and are you sure it is heat treated properly?
 
Right now, a Spyderco GB 2 in M4, and a Techno 2 in CTS-XHP.
But I've had the same results with many other steels.
 
I've found using my spyderco medium for touch ups works much better than a strop for me, and I use diamond compound.
 
The 3 biggest issues with stropping:

1. Your blade was not sharp to start with. This could mean that it has a large burr, or could mean that the apex is simply not ground all the way. Stropping is really only good for removing the last bits of burr and for mild polishing. If you have a large burr, that's standing straight up, it will feel sharp, but collapse when you use it for anything.

2. Too much force. This probably isn't you, but using too much force compresses the strop and makes it round over the edge as you stroke it on the strop. I think "feather light" is way to soft personally. I probably use about 1.5 to 3.0 pounds of force as a guess. Light to medium force.

3. Wrong angle. Too high of an angle rounds the edge also. What you REALLY want to watch is what you do at the end. A lot of people do this exaggerated motion at the end of the stropping stroke, which dramatically increases the angle right as they are leaving the strop. This rounds the edge. If you think you are doing this, finish by lifting the blade STRAIGHT up off of the strop at the end.

To find the proper angle, try this: Sit the blade on the strop almost flat, so the edge is not quite touching the strop. Now, move the blade, edge leading, slowly down the strop. At the same time, slowly increase the angle on the blade. When you feel the blade lightly bite into the strop, stop. That's close to the correct angle. There, or just a bit LESS of an angle should be perfect. Obviously stropping is done edge *trailing*. This edge leading technique is only use to find the angle.

#3 is probably your issue. Or it could be #1.

Good luck!

Brian.
 
Are they leather strops? You might try balsa wood or fir instead. A 1"x2" from Home Depot or something is usually flat enough that it doesn't need any processing before loading with compound.
 
bgentry said:
The 3 biggest issues with stropping:

1. Your blade was not sharp to start with. This could mean that it has a large burr, or could mean that the apex is simply not ground all the way. Stropping is really only good for removing the last bits of burr and for mild polishing. If you have a large burr, that's standing straight up, it will feel sharp, but collapse when you use it for anything.

2. Too much force. This probably isn't you, but using too much force compresses the strop and makes it round over the edge as you stroke it on the strop. I think "feather light" is way to soft personally. I probably use about 1.5 to 3.0 pounds of force as a guess. Light to medium force.

3. Wrong angle. Too high of an angle rounds the edge also. What you REALLY want to watch is what you do at the end. A lot of people do this exaggerated motion at the end of the stropping stroke, which dramatically increases the angle right as they are leaving the strop. This rounds the edge. If you think you are doing this, finish by lifting the blade STRAIGHT up off of the strop at the end.

To find the proper angle, try this: Sit the blade on the strop almost flat, so the edge is not quite touching the strop. Now, move the blade, edge leading, slowly down the strop. At the same time, slowly increase the angle on the blade. When you feel the blade lightly bite into the strop, stop. That's close to the correct angle. There, or just a bit LESS of an angle should be perfect. Obviously stropping is done edge *trailing*. This edge leading technique is only use to find the angle.

#3 is probably your issue. Or it could be #1.

Good luck!

Brian.
Click to expand...

1. Nope
2. Nope
3. Possible. I have used your technique before but maybe I just can't hold the angle constant on each strop pass.

I have no problem using the Sharpmaker to get a shaving sharp edge so I really don't need to strop. It's just that stropping has become my Moby Dick and I see it as a challenge to overcome. Maybe I should just forget it altogether.
 
I have had similar issues stropping in the past. Where I finally ended up is just to use the strop for taking off the last burr(s) after using the Sharpmaker, and for minor touch ups in between sharpenings. What finally got me to this (limited) success was learning to 'read' the edge, by touch and/or loupe.

Lenny said:
I have no problem using the Sharpmaker to get a shaving sharp edge so I really don't need to strop. It's just that stropping has become my Moby Dick and I see it as a challenge to overcome. Maybe I should just forget it altogether.
Click to expand...
 
It’s my understanding that for higher end steels such as m4, that diamond paste is recommended. Either way though, it shouldn’t be getting duller after stropping :confused:
 
Test cutting first, before stropping. Cut paper and see how it behaves. Then make some cuts into wood or heavy cardboard, then cut the paper again. If you see a drastic change in cutting after this, it suggests there was likely a burr on the edge, which folded or was stripped away. If cutting essentially comes to a halt after this, it also suggests the edge geometry behind the burr isn't very sharp, or perhaps it's not fully apexed from BOTH sides (a burr can still form from one side, before the other side is apexed). If only one side is apexed and a burr is formed from only that side, cutting performance will degrade immediately as soon as that burr gets stripped away.

The thing about stropping is, it should normally be very, very easy to notice an immediate improvement in sharpness, IF the edge was fully apexed from BOTH SIDES and ready for stropping to begin with. In fact, the better the stonework is before stropping, the simpler it'll be to strop with almost anything, with compound or not. The behavior described sounds like what'll happen if only a burr is doing all the cutting initially, after which that sharp burr gets scrubbed away, leaving poor or incomplete edge geometry behind it. Point being, good edge geometry AND a complete apex are what will cut, and what will keep cutting with durability.

Edited to add:
There's also the possibility of edge-rounding on the strop, due to using compounds not suited for the steel, and more so if too much stropping is done with inadequate compounds. Carbide-heavy steels like the ones mentioned won't respond as well to green compound especially, and warrant using diamond or cbn compounds, which can handle the vanadium carbides at the edge.
 
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Turn the blade over on the spine when you alternate passes, rather than the edge. Actually, if post a video of you stropping you'll be able to get more useful, non speculative/generic feedback.
 
Another thing i notice about stopping fails, make absolutely sure you are not adding angle at the end of your stroke. No flourish. Stop your stroke with a bit of strop to spare and carefully lift up and away. When I am really trying to get a crisp apex, I will often change the angle to a shallower angle right before I finish the stroke to be sure I am not rounding it.


I do find that stopping works when the edge is sharp. I don't take a dull knife to a strop.

I mostly only use it now to remove a stubborn bur etc?


One thing I have noticed over the years, is that after coming of ceramic rods, stopping actually removes bite from the edge. Doing a three finger "sticky" test on the edge, it has more bite before I strop.

I have never used diamond spray or paste for stopping, just cheap harbor freight aluminum oxide stick.

I am due for a new strop, as my home made one is all beat up. Only one side of the 4 is still usable. After 15 or so years of use.

My strop is too soft, so I compensate for this face with larger knives.


It can be frustrating.
 
I haven't found that stropping works very well or at all on higher-carbide steels like CPM-M4 and CTS-XHP. Steeling seems to work better for me -- just a couple of light strokes. That said, I haven't tried diamond compound, just chromium oxide, which does seem to work on high carbon steels with low carbide content.
 
Take a beater knife ink the edge and strop on a course stone and see where you are in relation to.the edge.
 
Wrap a sheet of paper around a bench stone, color the edge with Sharpie and strop. Now apply some compound to the paper and repeat.

What is probably happening is too high of an angle stropping, or the edge is already overly broad and the strop can't really help it.

Or you are using high carbide/high Vanadium steel, in which case you'll need diamond or cbn
 
As 2 or 3 folks said, if you're working with super steels that normally require diamonds to get best sharpening results, I find stropping to be slow and less helpful. It *can* work on these steels--I've seen folks like Michael Christy make it work in his Youtube videos--but it seems very time and labor intensive, and many steps and expensive materials (like diamond compounds in multiple grits) involved. Ultimately, you're just doing a very refined type of sharpening when you do this.

Instead, with super steel knives, you might consider to just skip traditional stropping altogether. Instead, for maintenance between sharpenings, just do a few very light sharpening passes on a high-grit stone (I use my DMT EEF, but folks here can probably suggest other options too).
 
You could be using the wrong angle or possibly to much pressure. I normally use Black and then green . At times I've used merely the jeans I'm wearing and it basically works the same. If you can barely hear a faint hiss when stropping you're on the sweet spot. You'll get it , we've all been there.:thumbsup:
 
Lenny said:
Everybody Else: "I strop my knife after using and it comes back to hair whittling sharp"
Me: "I strop my knife after using and it can't slice through butter" (a little exaggeration but you get the point)
Click to expand...

Yeah... no. A lot of folks play fast and loose with their words and descriptions. Don't compare your actual observations with the claims you read on the interwebs.
 
I can't believe nobody has pointed you to the Strop Sticky: Stropping Angle plus pressure

Stropping is frustrating to just about everybody in the beginning, and I was no different. I was getting the same results as you (ie: duller knife after stropping than before), and it wasn't until I understood what I was doing wrong and PRACTICED doing it the right way that it really started making a difference. Most things work like that. ;)

Bottom line is this: You need the correct balance of angle and pressure.

If you use very light pressure, you can be at the same angle (or even a little higher) than you sharpened at, and that will work fine. By light pressure I mean basically the weight of the blade.

However, if you use heavier pressure, you will need to be at a lower angle than you sharpened at as the leather will bend around the edge and make it dull.

I recommend starting light with the same angle, then after you master that, you can play around with a lower angle and more force.

Read the sticky that I linked in this post as it has some great visualizations that drive home what you are trying to do, and also what you are probably doing wrong.
 
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