Thread: Both sides of the hide?

BTH88,
A good example of a "modern" Russian strop would be the Illinois #827. On this one the working side is the reverse, flesh side of the beast and the back side is filled with small ridges left by an embossing/rolling process used to compress the leather. The front looks like compressed terrycloth. On a good example it works very well, on others it deteriorates into a wolley mess then a pumice stone can be used to get the texture desired.

Dovo and jemico both make a Russian strop that is a reddish color but no indication of other differences. Jemico did make a very small pebble grain model, also a deep red in color that was very hard surfaced and quite effective.

Tony

My homemade oak tanned cowhide strop works on both the finished and unfinished sides really well. To Tony's point, the unfinished side actually strops "faster" than the finished side (less resistence and smoother). This is probably due to both the smooth leather having more contact area and I also added a thin dressing of mink oil which adds drag. I enjoy using both sides and haven't yet figured out what finishing qualities are added by the separate sides.

Dewey

I think the "faster" you mentioned is the real advantage of the reverse side. I have found it makes a nice substitute for linen. I think Chris Moss on SMF is a big fan of preliminary stropping on rough leather and finishing on smooth leather and his suggestions spurred me to look at offereing my rough leather once again.

Tony

Originally Posted by Tony Miller

Dewey

I think the "faster" you mentioned is the real advantage of the reverse side. I have found it makes a nice substitute for linen. I think Chris Moss on SMF is a big fan of preliminary stropping on rough leather and finishing on smooth leather and his suggestions spurred me to look at offereing my rough leather once again.

Tony

Tony, FWIW if I were buying one of your strops right now, based on my limited experience, I would buy one with the rough leather option . BTW I hope to have one of your strops someday in the not too distant future.

Golf Balls and Dimples:

In the early days of golf in Scotland, golfers discovered that their old golf balls went farther than the new, smooth ones. The beat-up balls reacted differently to the forces they encountered while flying through the air. It wasn't long before golfers were intentionally pitting their brand-new balls to improve their games. By 1905, golf balls were being manufactured with dimples, as they have been ever since.
Why dimples?
All flying objects are subject to the forces of lift and drag. An airplane produces lift when the air flowing over its wings creates lower pressure than the air below, causing the plane to rise. At the same time, the plane's forward motion creates drag or resistance. A golf ball can produce lift in a similar fashion. For example, if a struck ball has backspin, which changes the flow of the air around the ball, it produces lift, a force that is perpendicular to its flight path. This is a result of high pressure being created at the bottom of the airborne ball relative to its top, and the lift is a consequence of these differences in pressure. At the same time, the struck ball also experiences drag, a retarding force that acts in the direction opposite to the direction of its flight path. Part of the drag force is due to the flow not being able to stay attached to the surface and come together on the back side of the ball. This separated flow forms a low-pressure wake behind the ball, and the difference between these pressures and the higher ones found on the front of the ball produce what is termed pressure drag.
The other part of the drag force experienced by the ball is due to skin friction, a tendency to pull the air nearest its surface along with it. It's just air rubbing on an object, which retards its motion. Skin friction depends largely on the pattern of airflow in the boundary layer very close to the surface of the ball. If the flow is smooth, or laminar, it has lower skin friction, but is less able to stay attached to the rear surface of the ball. A turbulent boundary layer, however, although having more skin friction, is better able to stay attached to the back of the ball. That is where the dimples come in.
Putting the dimples on a golf ball forces the boundary layer to transition from a laminar one to a turbulent one. The greater mixing of air in the turbulent boundary layer allows passing air to cling to the flying ball a little bit longer before it separates which in turn narrows the ball's wake, the region of low-pressure air created behind it. A smaller wake means less air pressure pulling on the back of a golf ball as it sails toward the green. In effect it's a positive trade-off: The ball pays a skin friction penalty, but gains a pressure drag advantage. The difference is huge in terms of the distance a golf ball can be driven. Dimpled balls can travel nearly twice as far as smooth ones.

<<<<In effect it's a positive trade-off: The ball pays a skin friction penalty, but gains a pressure drag advantage.>>>>

Much like the textured vs. smooth strop tradeoff, more friction, less surface contact vs. less sensation of friction, more surface contact. What we don't know though is the effect.

Thanks for the golf ball details. I know I have read that in the past but didn't remember where.

Tony

Originally Posted by Tony Miller

Dewey

I think the "faster" you mentioned is the real advantage of the reverse side. I have found it makes a nice substitute for linen. I think Chris Moss on SMF is a big fan of preliminary stropping on rough leather and finishing on smooth leather and his suggestions spurred me to look at offereing my rough leather once again.

Tony

A strop used in this manner could use the addition of a linen piece not so much to keen the blade but to dry the blade off after use. One side keening, one for finish, linen for drying?

The analogy doesn't hold up because when we consider air we're treating it as a fluid (oh, how I hated fluid dynamics ) and you can't say the metal of a blade does (no laminar and turbulent flow with a blade iirc. ) act like a fluid.

Tyres gripping in the case of racing slicks rely on them burning out and melting the surface of the tires which isn't exactly going to happen with our strops and razors either afaik.

The inner flesh side of the bits of leather I have are all a little rough for my taste, except for splits of course but then that's never been touching the flesh so to speak.

Murph,
The analogies were more to get people thinking about the differences.

Any thoughts on the textured strop surfaces increasing effectiveness or reducing it in regards to stropping. I know thw texture affects surface contact, reducing that but does the illusion of more resistance really pan out in practice?

Tony