Stropping: angle plus pressure

Stelth said:
Based on this statement I put some buffing compound on a board and stropped my GEC cattleknife. I've been having a hard time getting the wharncliffe sharp enough. Lo and behold the new method worked. It's really true that you have to experiment and different steels need different methods. Thanks for the inspiration!
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:thumbup:
Quite literally, I've never stopped experimenting with this, and I'm still finding better solutions for my own particular blades, just by continually trying new things out. Never stops being fun, and always teaches me something new. :)
 
As for your honing compound/polishing paste, you should all try Mothers Mag alumunim polish. Not sure if it has carbides or if its just purely chemical, but this stuff leaves a real mirror polish as well as a truly, scary sharp edge!
51jppSER5ZL._SL500_AA300_.jpg

Its used to polish chrome rims and such... so you get the idea. You can rub some on a strop and use it right away, or let it sit for awhile and let it dry out. It works quickly and effectively, so you wont need multiple strops with different micron levels... this does it all.
 
viper2788 said:
As for your honing compound/polishing paste, you should all try Mothers Mag alumunim polish. Not sure if it has carbides or if its just purely chemical, but this stuff leaves a real mirror polish as well as a truly, scary sharp edge!
51jppSER5ZL._SL500_AA300_.jpg

Its used to polish chrome rims and such... so you get the idea. You can rub some on a strop and use it right away, or let it sit for awhile and let it dry out. It works quickly and effectively, so you wont need multiple strops with different micron levels... this does it all.
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http://www.tompkins-co.org/msds/m2685.pdf
 
The Mother's Mag polish likely uses aluminum oxide or silica, or both, as abrasives. The MSDS referenced above is somewhat misleading, because they ordinarily list only ingredients deemed to be toxic or otherwise hazardous (poison, fire hazards, fumes, irritants, etc.). Sometimes you'll see other ingredients listed there, but it's not required for the makers to list such info in the MSDS, as it may be proprietary ('trade secrets', etc.). By themselves, neither aluminum oxide nor silica are considered hazardous or toxic (both are occasionally used in toothpaste, for example).
 
Great representation! I really enjoy visual references and this has to be one of the best I've seen on stropping. I'd even recommend you post this up on StraightRazorPlace forums, they'd love it.
 
Got tired of doing a search every time I wanted to see Stitchawl's recommendation for how to prepare a strop - decided to fold it into an existing sticky:


Step by step:
1. Wet the leather. No need to soak it for any length of time. Running it under the tap for a second or two, front and back, is enough.
2. VERY IMPORTANT - let the leather dry for a while. Before you wet it it was a light tan color. Water darkened it a lot. Let it dry until it's about half-way back to its original color. At THAT point it will be almost as squishy as modeling clay.
3. Use a large diameter rolling pin, the heavier the better. Marble pastry pins are great for this, but even a piece of 3-4" PCV pipe will work. Now start rolling on the smooth side of the leather. Roll from end to end evenly, bearing down on the roller. Do this for 4-5 minutes, not just one minute. This will firm up the leather. If you are going to use this for a bare leather strop, roll it for 10-15 minutes. The rolling will force more silicates to migrate to the top of the leather.
4. Let it dry naturally, then glue to a backing or use as a hanging strop.

Keep in mind that any natural oil... ANY oil... is going to soften the leather. Makes no difference if it's Lexol or Olive oil. Lexol is more compatible with leather. Olive oil won't hurt it. But both will soften the leather... Soooo... if you really want a good firm strop, but need to put some sort of strop conditioner on it, dab it on a finger tip and rub it out well. Don't paint it on with a brush, or rub it on with a saturated cloth, or pour it on and rub away the excess. None of the above will harm the leather, but they will significantly soften the leather more than is needed to preserve it. The strop conditioner I use on my grandfathers old hanging strop has the consistency of thicker Vaseline, and I use less than a pea-size for the entire strop once a year. My grandfather used it every day as did my dad. I'm guessing that this stop is about 75 years old... and the leather looks brand new.


Stitchawl
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Something I have found, is that some leather strops which appear at first glance to be level, are in fact not level. The unaided eye can sometimes not pick up on it, and closer inspection of the bevel, will reveal that maybe the strop is not level. This is assuming you hold the same angle every stroke.

I have a leather paddle strop, and a split top leather strop. The paddle strop is almost level but not quite. I don't mess with it much, because it refuses to take any medium, be it compound, spray or paste. My split top leather would be an excellent strop, but I have found that it is not very flat. I do not have the mounting base it is made to go on, and no one seems to be supplying that particular base right now (everyone appears to be out of stock).

I am not trying to circumvent the previous posts... but there are too many variables that must be completely on par and perfect if you are stropping on an uneven, and off level strop.
 
I read this post yesterday and realized that it was the most informative post I've ever read on BF.
Then last night in a deep slumber I had a dream where I was stropping. Can't remember what knife it was but the strop was green. Don't get all Freudian on me. A strop is just a strop. At the ripe age of 56 some things just are not what they used to be.
I love this place.
 
Many thanks to OP!!! This helped a lot.......except the whole left side of my body is hairless:)
 
I was just about to post a question about mothers mag polish I am so glad I read this post first this is why I love Bladeforums....
 
Ref: TwinDog

Now just cuz i'm new here doesnt mean i can't mouth-off .. just as anyone here can tell me to shaddup ;))) In any event, i noticed this article and commend you for presenting a logical, thought-out, and well-explained item. As is true for many things, the most 'logical' description might not be really either correct or possible to act out in practice. IMHO, its the latter point that bothers me .. Although your angles and pressure arguements are well-described and factual, the actual art of applying them to the fact of having a blade in hand and a strop presents new issues ...
Our hands are not 'calibrated' in angles or radians ... we can merely do our 'best guess' at applying the blade .. and usually that application is wrong.
Why? cuz there's only one 'best angle/pressure combo' and about 8 million wrong ones .. So : " what's the chances" ???? Pretty bad, I suggest.

Far better to reduce the problem to a far simpler solution:
First, is the issue of how one flips the blade for the following strop stroke !!! (Rarely discussed!) . In nearly ALL video presentations of this simple act show it to be done incorrectly: showing the blade being rotated around the axis of it's sharp edge! Why is this wrong?? Cuz we're human .. it's impossible not to inadvertently touch that fine edge to the strop in a way destructive to the edge itself .. Every once in a while, maybe cuz the dog just leaned against yur leg at the wrong moment .. BAM! the edge is harmed by a careless touching of the edge and a 90deg or, Goddess forbid, 130 deg angle!!! This is now how barbers strop blades.
Solving this and the angle problem involves two steps: first:
Keep the blade .. its entire width, totally in contact with the 'hanging' strop! (Notice: NOT a strop mounted to an unforgiving board or bench! .. the reason will be clear here: ..)
Then, flip the blade at its axis defined by the BACK edge of the blade! Let the fine edge 'flip over aWAY from the strop! ...' Doing it this way totally prevents risk of stropping ruining the edge. AND lets ya do it very quickly !!!!! as in: SLAP!SLAP!SLAP!SLAP! as the flipped blade is quickly drawn across the strop.
So: about angle and pressure: Because the strop is hanging from it's fastening at the wall, you can easily adjust pressure and angle by how your NON-stropping hand is holding the strop! It's not possible to apply a blade with any pressure at all to a horizontally-suspended strop without deflecting the strop downwards .. Can't be done ..Laws of Physics, ya know! ..
But that is not to say we cant use that fact to adjust .. by using the strength of hand/arm as it holds the free end of the strop ... the angle at which the edge touches the (slightly curved) strop.
I suggest that those having stropping issues try this method .. Start with some 'throw-away' blade and see just how amazingly fast you can do these meneuvers with very little risk ...
And do get back to me ... there sure is more to this topic than we've discussed here!
And thank you for your very-well-presented article!! Impressive!

tkjtkj
 
Hey TK:

Thanks for the kind words and welcome to the forum.

Stropping is an art. It's difficult to get the pressure and angle exactly correct, but on a leather strop there is some forgiveness because of the give in the leather. That forgiveness improves your odds of finding a good angle/pressure combination. To maintain a perfect V edge, you have to get everything exactly right. But if you're just a bit off, you can also get a slightly convexed microbevel that works just fine. I believe that most stropping produces this convexed microbevel.

Stropping a razor on a belt is different than stropping a knife on a flat strop. I don't strop razors, but my understanding is that the razor is laid flat on the belt for the entire stropping stroke. The height of the razor spine keeps the angle constant. Knives use a steeper edge angle and don't work that way. With a razor, you have a natural guide to keep the angle constant, so all you have to do is maintain the right pressure so you don't roll the edge. And, as you say, you flip the razor for the return spring on the spine of the blade. You never have to let the spine leave the leather, although you have to maintain the correct tension on the belt. With knives, you want to lift the blade straight up at the end of a stroke so the angle isn't changed at the very end. If you laid a knife blade flat, as with the razor, the edge would not contact the strop, and you would just smooth off the edge shoulder.

With knives on a flat strop, there are a lot of combinations of pressure and angle that work and a lot that don't, which is why stropping is an art, like freehand sharpening. The idea is to find the right combination of pressure and angle that works for you, and than develop the muscle memory to maintain that combination.
 
First off, wonderful thread.

Now, my question is, at what level of sharpness is it appropriate to strop? For example, when I finish with my fine stones on my Lanksy Crockstick, my knife is sharp enough to shave hair, but roughly/requires a good deal of pressure.

Have I achieved a sufficient level of sharpness from the stones to begin stropping?

Thanks,
Mark
 
I get my edges as sharp as I can with stones before I finish with stropping, especially with the super-hard, high-alloy steels. The sharper the stone ground edge, the better the results from stropping. The last stone I use is the Wicked Edge 1600 ceramic. The edge will shave easily after that, although I slice thin desk paper as a test. Stropping refines that edge and gives it an extra kick in sharpness, but it doesn't remove much metal.

I haven't used your crockstick, but it should be fine as a finishing stone, especially if you are using very light strokes at the end and you can no longer detect a burr.
 
mark greenman said:
First off, wonderful thread.

Now, my question is, at what level of sharpness is it appropriate to strop? For example, when I finish with my fine stones on my Lanksy Crockstick, my knife is sharp enough to shave hair, but roughly/requires a good deal of pressure.

Have I achieved a sufficient level of sharpness from the stones to begin stropping?

Thanks,
Mark
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This is how I'd interpret what's likely going on, and therefore deciding if my edge is ready for stropping:

The 'roughness' of shaving hair, if I interpret your meaning correctly, may be due to the coarseness of the edge finish; either not going far enough in grit, or not fully cleaning up coarse scratch patterns from earlier steps. And, 'requires a good deal of pressure' suggests to me that either the edge isn't as fully apexed as it could be, or the edge geometry (angle) is a little too wide/thick to shave well.

In either case, both would suggest that more work could be done on the hones (rods) of the sharpener, before stropping. When the edge is ready for stropping, it should already be thin enough (angle/geometry) and refined enough (edge finish) to make hairs pop off easily, but perhaps you may notice it does so only from one side of the edge (suggests a burr has formed, but is angled/bent slightly to one side or the other). The burr itself should be thin/sharp enough to shave or pop hairs easily. But being that it's a burr, it won't be durable. This is where stropping should clean up the burr, and reveal if the apex geometry behind it is still crisp and shaving-sharp. At this stage, it shouldn't take many passes on a strop to see an immediate improvement in both shaving sharpness and durability, which can be tested by drawing the edge through some hardwood, cross-grain, two or three strokes, and then re-checking for shaving sharpness. Most shaving burrs, if still present, would fold over or come off after the cross-cut through hardwood. If the remaining edge geometry is still good and fully apexed from both sides, you should see improvement. If it's not good, then you'll quickly see the cutting/shaving performance drop off after the burr is removed. This likely indicates the apex needs more refinement (on the hones/rods), so the bevels on each side are fully flat and intersect sharply at the apex.


David
 
Wow, what a tremendous amount of information and experience. Thanks to the OP and contributors to helping me get started on my education of sharpening, stropping, and achieving all the sharpness the steel of my blade can offer.
 
Obsessed with Edges said:
This is how I'd interpret what's likely going on, and therefore deciding if my edge is ready for stropping:

The 'roughness' of shaving hair, if I interpret your meaning correctly, may be due to the coarseness of the edge finish; either not going far enough in grit, or not fully cleaning up coarse scratch patterns from earlier steps. And, 'requires a good deal of pressure' suggests to me that either the edge isn't as fully apexed as it could be, or the edge geometry (angle) is a little too wide/thick to shave well.

In either case, both would suggest that more work could be done on the hones (rods) of the sharpener, before stropping. When the edge is ready for stropping, it should already be thin enough (angle/geometry) and refined enough (edge finish) to make hairs pop off easily, but perhaps you may notice it does so only from one side of the edge (suggests a burr has formed, but is angled/bent slightly to one side or the other). The burr itself should be thin/sharp enough to shave or pop hairs easily. But being that it's a burr, it won't be durable. This is where stropping should clean up the burr, and reveal if the apex geometry behind it is still crisp and shaving-sharp. At this stage, it shouldn't take many passes on a strop to see an immediate improvement in both shaving sharpness and durability, which can be tested by drawing the edge through some hardwood, cross-grain, two or three strokes, and then re-checking for shaving sharpness. Most shaving burrs, if still present, would fold over or come off after the cross-cut through hardwood. If the remaining edge geometry is still good and fully apexed from both sides, you should see improvement. If it's not good, then you'll quickly see the cutting/shaving performance drop off after the burr is removed. This likely indicates the apex needs more refinement (on the hones/rods), so the bevels on each side are fully flat and intersect sharply at the apex.


David
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Thank you David, that was excellent information. I'm going to give the hardwood a try tomorrow, and I'm getting a Jewler's loupe soon as well.
 
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