Stropping, what to get

I agree with Sadden. Any edge can be intentionally convexed with a strop is one so desires, or unintentionally if one is careless. The thicker and softer the strop, the more difficult it is to avoid convexity.

I maintain my convex edges with nice thick "Russian Red" leather strops. My "V" edges are stropped on nanocloth and/or Kangaroo.

Nano cloth and Kangaroo are quite thin, and readily adaptable to Edge-Pro mounts, allowing a degree of uniformity in stropping unavailable with free hand stropping.
 
I agree with Sadden. Any edge can be intentionally convexed with a strop is one so desires, or unintentionally if one is careless. The thicker and softer the strop, the more difficult it is to avoid convexity.

I maintain my convex edges with nice thick "Russian Red" leather strops. My "V" edges are stropped on nanocloth and/or Kangaroo.

Nano cloth and Kangaroo are quite thin, and readily adaptable to Edge-Pro mounts, allowing a degree of uniformity in stropping unavailable with free hand stropping.

You're correct in that the softer a strop is, the more difficult to avoid convexing the edge. This is why properly-made barber strops are so hard and dense. As has been said in other threads, when a fingernail has been gently pressed into this kangaroo leather strop being sold, it does indent the leather. That is too soft for a strop unless one is willing too go verrrry slowly when stropping to insure correct pressure. But stropping isn't supposed to be a verrrry slow process. It's a quick 10-15 stroke finish to a sharpening process. Anything more and stropping becomes just another form of sharpening. Edge-trailing, but still 'sharpening.'


Stitchawl
 
Lets examine fingernail indentation in more detail , and how it may relate to stropping.

Lets look at stropping pressure in terms of PSI (or pounds per square inch).

So we have a 3 inch wide strop. And a Japanese chefs knife with a 1 inch tall bevel. While stropping if I put the strop on a scale and zero it out , then use 3 pounds of pressure I am in fact stropping with 1 PSI , given that we can all agree that 1x3 is equal to 3 square inches.

Scaling this down to the surface area of a fingernail jammed topways into a strop we can figure this out using my finger nail as an example.

Width = ¾” = 0.75”
Height = 1/32” = 0.03125”

This means that our surface area is equal to 0.75 x 0.03125 or 0.0234375 square inches.
From here we take 3 and divide by 0.0234375 giving us 128.

This is 128 times less the surface area of the Japanese chefs knife used above. So in order to distend the strop that much , using the knife , we would have to apply 128 PSI or 384 pounds on a scale of downwards stropping pressure.

This is drastically more pressure than any person on this board is stropping with. This makes testing using “fingernail indentation method” an extremely poor methodology , compared to the actual requirements of a strop.
 
We're getting a bit off topic here, even the OP is no longer responding. Anyway, there are two test anyone can use to see if how they use their strop might turn into an issue. The first is to have a direct light on your set-up and see how the light changes from the open surface of your strop to the region right at the cutting edge as you use it. If you can see light bending at the cutting edge, the surface is deflecting, the edge is rounding to some extent. If one only uses the strop for a mild finish polish, not an issue, but then that would depend on how much it is deflecting.

Second test is to go from strop, back to stone and see how long it takes to grind a new flat on the cutting edge (assuming reasonably flat bevel initially coming off the stone). You can also use this to see how much one is rounding the bevel off with higher grit polishing stone by going back to a medium grit and checking the same characteristics. This test is more accurate than the lighting one as you can estimate how many degrees have been ground off the bevel and where. If you can grind a fresh edge off the strop in very short order, and observe no real unintentional convexing, whatever you're using has good properties for a strop used with compound.

Generally, most people will get perfectly good if not excellent results using a sheet of paper wrapped around a stone or similar if using compound. I can't speak to the multiple step processes that some use, but for a simple users edge that might only take a few minutes to maintain and under 20 minutes to completely re-set on a stone - stropping a few times with a single compound off the final stone. Especially for long term maintenance, this method has essentially zero rounding yet will hold onto an abrasive grit and allow it to work more uniformly. For burnishing, plain paper works very well too, and can be tried out easily and quickly - buy something more exotic if it fails to give expected results.

As for the compound, I still recommend Flexcut Gold.

Martin
 
I'll piggyback my questions on this thread, if ya'll don't mind.

What's the most economical .25 to .5 micron spray or paste? I don't mind admitting that I'm balking at HandAmerica prices.

Also, I already have a few leather strops. Where are you guys buying nanocloth strops (or just the nanocloth itself.)
 
Thanks. I should have mentioned I already have green compound from econabrasives (where I got my 1x30 belts) and a full set of black, white, green compounds from one of the strop makers selling on ebay.

I'm looking for something finer (of course there's some debate over what micron each green compound actually is.). Maybe mine is .50 microns. I can't really be sure, though, so I'll probably go down to .25 with a spray.
 
@HH --

Where does the Flexcut (gold) fit between white and CrO2 (green)?

OT

You can think of it as being a very aggressive white, depending on what brand of white you're using. Some of the abrasives are sub-micron, some are a bit larger, maybe 3 or 4u. Not sure if it contains anything larger - I'd be surprised if it did, but not amazed. I do not know the actual distribution, but could break it down with some mineral oil and take a look (and some pics with scale) under the microscope if you're interested. It leaves a slight haze and a real catchy edge if used on a hardwood lap with some oil, on a soft strop it can make a near mirror finish. Have read of a number of straight razor users that apply it as a final compound followed by plain leather - it can readily make a hair dropping edge.

In my experience, compounds with several sizes of abrasive work a lot better for general use then single grit compounds. I recall Lee Valley catching some static re their green carving compound after a knife nut discovered it contained a range of grit sizes. The company that makes it for them is Formax, who also make a green microhoning compound that contains a very precise and uniform particle. The range of sizes for the carving formula isn't a production error, but an intentional strategy to get more oompf out of the compound, undoubtedly the result of research from a bunch of folks that understand woodworking edges better than most. It enables the grit to do some repair work and still hone very fine. A single fine abrasive cannot readily repair or refresh a worn edge, and a larger grit doesn't leave a nice fine edge. The effect doesn't default to the largest grit in the formula, they actually work together. Flexcut uses a similar strategy and so do I.

When I was formulating compound for use on my Washboard I did a large number of head to head tests with single and multi grit compounds, the multi grit outperformed the single grit in every trial save for super duper high polish edges, and then it had to be used in conjunction with another grit or some additional pre-polish step. On its own it was not a good fit for indefinite maintenance or for finish off of a medium to fine grit stone. Keeping in mind my target edge didn't have to drop a hanging hair but just had to get to tree-topping and remain catchy, and do so quickly and reliably with a single step. With a bit of finesse and time using the same compound I can reliably get to a hair whittling edge as well, but that isn't really what its made for. Depending on edge geometry, tree-topping is already at the upper limit for EDU or even most specialty use aside from shaving. My Chef's knife using my compound, almost ruined a watermelon when it split a large number of the seeds in two as I sliced one up last Summer. One thing to spit out the seeds, another when its like spitting out pieces of toothpick...:)

Martin
 
Thanks.

So it looks like for wood carving knives it's white, yellow then green.

For meat carvers, white then finish with yellow.

OT
 
Thanks.

So it looks like for wood carving knives it's white, yellow then green.

For meat carvers, white then finish with yellow.

OT


Hard to say, some white compounds are finer than the yellow. Ryobi comes to mind. Color of compounds can be misleading, especially across manufacturers, you have to use 'em or get an accurate description of how they work from someone else in order to have a an idea of what they might be good for.

Martin
 
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