Stropping on cardboard

[FortyTwoBlades]

I've posted this before, but I guess it bears repeating here...
Leather is not magic. Neither is cardboard, paper, your jeans or the palms of your hands.
What they all have in common are 'silicates...' those tiny abrasive particles, MUCH smaller than 98% of what are found in various compounds, and these are the 'magic' to be had in stropping on bare surfaces.
All carbon-based lifeforms contain silicates to some degree. Green grass has a lot of silicates, and when the cows eat the grass, they now have silicates in their skin. Vegetables have silicates so when you eat them, you have silicates in your skin. Trees have silicates, and when you grind them up and make paper, the paper has silicates. Jeans are made of cotton, cotton has silicates so your jeans now have that magic micro-abrasive quality that allows us to strop on our thighs.

Leather, properly processed, has MORE silicates than cotton cloth. Especially horse hide. It has more silicates per square inch than cow hide. So does kangaroo hide. BUT NOT A LOT MORE! Just more. Without real science (and so just making up numbers,) if it takes 6-8 strokes on Horse hide, it may take 8-10 strokes on cowhide and 12 strokes on paper or on your jeans. There is no difference in the quantity of silicates in copy paper or a shirt cardboard, and it's those silicates that are doing the honing, not the smooth or rough surface of the paper/cardboard strop. Magazine covers are a horse of a different color. They are 'coated stock.' The coating is a fine clay, which is abrasive in its own right. And because leather lasts longer, barbers use leather strops rather than cardboard toilet tubes. Looks more professional, too.

Different stropping materials do give us different feedbacks while we are stropping. And we get used to the feedback of the strops that we use, so we may feel that one is 'better' than another. Rougher surfaces really have little effect when stropping, other than giving different feedbacks. The bottom line is that it is the silicates that are doing the work. If you doubt this, just try stopping on a rough piece of Cordura Nylon and see what happens. Then try stopping on your jeans or a piece of news print paper. The magic is in the silicates.

It's not just the silicates. Stropping on bare material is usually more about aligning the apex than abrading it. It's pulling the rolled over fin of the edge apex out straight. My experience with scything bears that out quite observably. Scythe edges are as thin-angled as those of straight razors, only about 7° per side. American scythe blades are made of very hard steel that takes and holds an excellent edge, and yet because it's so thin and usually honed with a coarse grit stone to maximize slicing ability, it's fairly easy for the apex to deform microscopically and create an artificial flat that causes an observable drop in cutting performance. I use a bare wooden stick to "strop" the blade, allowing the wood to catch the rolled over steel and pull it back straight. This restores the edge without any significant abrasive action, and I'm usually able to do it 3-5 times before I actually wear down the edge enough to require using the stone. Yes, some abrasion certainly goes on--especially as the wood eventually becomes dirtied--but it's minimal compared to the effect being mechanically provided by the stropping.

 

[HeavyHanded]

As the surface gets harder, a bit of burnishing comes into play (if enough force is used). Not very helpful on higher carbide steels, but on carbon and finer grained stainless this is a very useful mechanism.

Very true re silicates, they are everywhere in nature. Most of the bioavailable stuff is in the form of silica salts, but there are a good bit of oxides present as well. Campfire ash has a high percentage, regardless of wood type.

 

[stitchawl]

It's not just the silicates. Stropping on bare material is usually more about aligning the apex than abrading it. It's pulling the rolled over fin of the edge apex out straight.

... which isn't stropping. It's aligning. Steel, being considerably harder than cardboard, probably won't do much 'bending' (aligning) with the light pressure used when stropping on a shirt cardboard or one's pant leg.

I use a bare wooden stick to "strop" the blade

Rubbed with pressure, I can see a hard stick of wood bending the very thin edge... However, wood, of course, contains the same amount of silicates as any other vegetable matter from which paper and cardboard are made... which work well for stropping. So in effect, you are actually aligning the edge and stropping it at the same time.

 

[FortyTwoBlades]

... which isn't stropping. It's aligning. Steel, being considerably harder than cardboard, probably won't do much 'bending' (aligning) with the light pressure used when stropping on a shirt cardboard or one's pant leg.

It's certainly a part of stropping. Stopping accomplishes two things in varying degrees depending on the medium and abrasive used. It both aligns and polishes the edge. In the case of bare wood it is more alignment than polishing, as the amount of abrasive action caused by the wood is extremely minimal.

Rubbed with pressure, I can see a hard stick of wood bending the very thin edge... However, wood, of course, contains the same amount of silicates as any other vegetable matter from which paper and cardboard are made... which work well for stropping. So in effect, you are actually aligning the edge and stropping it at the same time.

In the very post you quoted I acknowledged that some minimal abrasive action does occur, but it's so little as to be considered negligible.

 

[Numbersman23]

I prefer a piece of leather belt, but I have used cardboard. It works OK, sometimes. A legal pad or similar pad works OK, too.