Stropping easily ruin edge?

[J-P SAN]

How hard is it to ruin good edge on a strop? I know that base material you are stropping into has big effect on that. Is denim most forgiving? Is hard or bending strop better?

 

[dkb45]

You want a strop that is stiff. Hard leather is great. I have had a few edges that seemed duller after stropping because my angles were wrong and I rounded the apex. Match your sharpening angle and keep the pressure low and you should be fine.

Cardboard, hard felt, and balsa are also good strop material.

 

[Obsessed with Edges]

How hard is it to ruin good edge on a strop? I know that base material you are stropping into has big effect on that. Is denim most forgiving? Is hard or bending strop better?

Lots of variables. But generally speaking, you want a strop that compresses the LEAST under your blade's edge. This means harder/stiffer bedding for your compound is generally best. With fabric like denim, there are even variations in how much that'll compress (thinner fabrics over hard backing will obviously compress less than a heavier/thicker fabric, for example). Finding a backing that minimizes compression, AND holds the compound exceptionally well, is a good target to shoot for.

The one exception where a 'bendy' strop can work well, is with a hanging strop (like a barber's strop). The free-hanging use of it means it's difficult to compress the strop material, because there's no hard backstop against which to compress it. The strop as a whole tends to deflect away from heavy pressure, which helps to moderate how much pressure is exerted laterally against a blade's edge; therefore it reduces the tendency of a softer/thicker material to compress under the blade's edge. When used correctly, the blade will just lightly skim along the surface of the strop, and any chance of edge-rounding is minimized.

Edit:
And there are lots of ways to ruin a good edge on a strop, only some of which involve the softness or compressibility of the substrate. 2nd only to that, making poor choices of compounds would likely be up there too. Different steels will respond in vastly different ways to a given compound, which will sometimes be too aggressive and over-polish the 'bite' out of an edge, and more so on a softer substrate.


David

 

[Kai Winters]

I've started with a shaving sharp edge after the Lansky treatment and rounded it over when stropping. It is not the stropping that did this but rather my incorrect angle while stropping that rounded the edge.
I'm much more careful and actually use far fewer strokes when stropping to refine the edge.
My EDC is the ZT566 Elmax and is the knife I'm talking about.

 

[HeavyHanded]

Incorrect use of a strop, either with poor technique or trying to use it in a mode it can't accomplish, will ruin an edge. Properly used it works great for refining an edge and doing some light deburring. Over-reliance on it for deburring will often lead to problems maintaining apex geometry (edge will round).

Either way in most cases it will lead to a more uniform edge, so if intending to craft a super catchy, toothy edge it can compromise your results.

Stropping changes character quite a bit as you go from one method to another, some forms use more of a lapping action, some more of a grind, some more of a sanding action - it all depends on how hard the backing is and how much mobility the abrasive has. In general on a firm leather strop, one is best off refining the edge on a stone very close to the rating of the stropping abrasive and using the strop only a few light passes to effect the apex. The overall effect goes all over the map as you change variables and can really push (confuse) the definition of just what "stropping" is.

 

[Cheshkasaba]

Yeah i had the same problem, at first i thought it was because of the leather, later learned that my technique was a bit off, used too much force (angle was lower than on the stone) and it compressed the leather, rounding my apex and it wouldnt even shave my hair.