Which Strop (Honing) Compounds

[jljohn]

Hi all,

I'm pretty new here, and I have a question about strops. I've been using knives for decades now, and in the last few years have gotten more serious about precise sharpening. I'm currently using water stones (Chosera 400, 1000, & 3000, but I use the 1000 almost exclusively) for my kitchen knives, and an EdgePro Apex 3 (with stones up to 1000) for my outdoor knives. I am looking at getting a convex Bark River, and I have a GB Wildlife Hatchet, so I'm thinking I should add some strops to this kit, both for the Bark River and the hatchet, and for further refining my other blades. I am looking at some of the leather hones from places like KnivesShipFree and DLT, and I am wondering many leather surfaces I need? Is 2 enough, or should I get 4? Black and Green Compound or Black, Green, White, and then plain leather? Any other options to consider?

Thanks!

 

[Rey HRH]

I've bought decent plain leather strops along with ALOX compounds, green compound, diamond spray, and even suspended polycrystalline .25 micron diamond for use on basswood strops. I've also made horsebutt leather strops prepared according to some specific instructions. Having said that, I went on a lark and also bought Knives Plus Strop block and it can achieve sharpness very easily and effortlessly. I'm thinking it's because it's supersaturated with compound and maybe that's how it's suppose to work. I've tried the knives plus strop on au8, sv35n, and elmax and I could easily tell the difference in just a few strokes. I thought before that chromium didn't work on "super steels." Fortunately, I was wrong. So I can confidently recommend Knives Plus Strop.

I am going back to see if I can supersaturate my basswood strop with the diamond and see if that's the key to refining the edge with fewer strokes.

 

[irona]

I'm pretty sure you'll be safe with just a Knives Plus Strop and green compound.


Sent from my iPhone using Tapatalk

 

[HeavyHanded]

Hi all,

I'm pretty new here, and I have a question about strops. I've been using knives for decades now, and in the last few years have gotten more serious about precise sharpening. I'm currently using water stones (Chosera 400, 1000, & 3000, but I use the 1000 almost exclusively) for my kitchen knives, and an EdgePro Apex 3 (with stones up to 1000) for my outdoor knives. I am looking at getting a convex Bark River, and I have a GB Wildlife Hatchet, so I'm thinking I should add some strops to this kit, both for the Bark River and the hatchet, and for further refining my other blades. I am looking at some of the leather hones from places like KnivesShipFree and DLT, and I am wondering many leather surfaces I need? Is 2 enough, or should I get 4? Black and Green Compound or Black, Green, White, and then plain leather? Any other options to consider?

Thanks!

You could simply smear some of the mud from your waterstone(s) on a sheet of paper, let it dry, and wrap it around another dry stone you have sitting around. Once it loads up, make another. Alternatively I have smeared waterstone mud on the edge of a cutting board and stropped with it still damp.

The 3k mud will produce a much finer scratch pattern over paper than it does in the stone. You can use the 1k mud as well which should be in the range of most black compounds at 20 micron or so. The 3k is about 5 micron, small enough to make a very refined edge. Additional layers of paper will make the "strop" progressively softer and the edge more refined but also more liable to round somewhat if misused.

My personal favorite for compound (after the materials I make for my Washboard) is Flexcut Gold.

 

[Danketch]

If you are getting a 3V Bark River (you absolutely should) I would and do use CBN compound (16 and 8 micron) and diamond spray/paste in 6 and 1 micron from Hand American and DMT on basswood/denim/balsa/cotton duck, on the Washboard at home, or set on a coarse surface if out in the wilds. If it's A2, Bark River black and white compound. I personally don't use/get much benefit from the green, but the white is excellent.

 

[Obsessed with Edges]

I'd also not bother with green compound for steels with much vanadium content. It's effect can be noticed in situations where the strop is basically just knocking loosely attached and weakened burrs from the edge immediately after resharpening on a stone, and/or just straightening the burrs out. In such instances, the perceived improvement in sharpness comes mainly from that. But the same effect will also be noticed in stropping on virtually anything, such as bare leather or denim, for the same reasons. In terms of actually thinning the edge or polishing, green will do virtually nothing on such steels otherwise, as it's nowhere near hard enough to shape or polish the carbides in them, and instead just affecting the surrounding matrix steel and essentially undercutting the carbides and weakening their support near the edge. The result is an edge which will gradually round off and lose all it's 'bite' with more stropping, as the undercut carbides will just eventually break away and leave the apex thicker/broader in the process. For very hard carbides, diamond or CBN compounds will actually continue to thin and shape them on a strop, which greatly extends the strop's usefulness for such steels and also extends the time the edge can be tuned up on the strop alone, before it needs reworking on stones to restore it fully.


David

 

[Steel_Drake]

If you are getting a 3V Bark River (you absolutely should) I would and do use CBN compound (16 and 8 micron) and diamond spray/paste in 6 and 1 micron from Hand American and DMT on basswood/denim/balsa/cotton duck, on the Washboard at home, or set on a coarse surface if out in the wilds. If it's A2, Bark River black and white compound. I personally don't use/get much benefit from the green, but the white is excellent.

To add to this, those white/black/green type compounds should be avoided for basically any steel with a significant carbide volume as the abrasive in those compounds struggles to cut the carbides and tends to end up troughing the steel matrix around the carbides at the apex, leaving a weak apex severely prone to carbide tear out. CBN or diamond sprays, emulsions and pastes avoid these issues because CBN or diamond will cut the carbides just as easily as the steel matrix around them.

I'll also add that the 16 micron CBN emulsion already produces an apex finish similar to an 8000 grit waterstone when used on a leather strop as a result of the particles of CBN embedding partially into the leather surface, and because the leather surface is compressible and deforms around the apex when stropping. These two factors combine to significantly reduce the scratch depth produced compared to a non-compressible abrasive and so lead to a fairly coarse sounding particulate abrasive producing an apex finish comparable to a much higher grit waterstone.

Using anything finer than 16 micron CBN on leather for a large number of passes is likely to eliminate most or all slicing aggression from the apex and leave a straight razor like finish with extreme push cutting sharpness but virtually zero slicing aggression. For most pocket and utility knife type uses, that is not a very practical finish. As a result I'd suggest avoiding compounds any finer than 16 micron CBN or ~10-12 micron diamond paste (the diamond pastes don't embed as deep in the leather and are less finely graded than the CBN and so you need to go a few microns finer with diamond to get similar results compared to CBN) if you want to avoid having to worry about ending up with the dreaded "killed edge" or "overly stropped edge" or "overly buffed edge" or mistakenly assumed to be "rounded over edge."

 

[jljohn]

Thanks for the responses--this is very informative. In light of the last two responses, let me ask a couple followups:

First, for the convexed edges (for which the strops will be my complete sharpening system) I will have A2 and the unknown steel that Gransfors Bruks uses, and in my sporting knives, I have W2, D2, S35VN, 154CM, and 440C. Do you recommed the CBN / Diamond paste for this group?

Second, am I understanding you to say that the best stropping option for finishing my knives is no finer than a few passes on 16 micron CBN on leather? If so, great! For my sporting knives, do I need an intermediate step between the EdgePro 1000 and the CBN 16 micron? Also, what courser strop-based options would you recommend for bringing back an edge on the convex grinds?

Thanks!

 

[Danketch]

This is a good point to bring up- the stropping medium effects the sharpening action/conform-ability as well. 16 micron CBN on a leather strop (assuming all other variable the same) will leave a noticeably different edge than the same on Denim on the Washboard or on a coarse - non-conformable hard surface. I personally can barely avoid rounding my convex edges on leather strops, but give me a hard (that's what she said) surface, and I can make the same knife whisk off arm hairs with no trouble.

Also to jljohn- I haven't gotten any yet, but recommended by a knowledgeable few on here is 3M Diamond lapping film for stropping/refining an edge.

 

[HeavyHanded]

For high Vanadium steels the diamond lapping film works great in this role. It can be cleaned, has very little give, a single sheet can last practically forever if not abused.

I'm not as big a fan on other types of steel though, a hard strop with AlumOx or SiC works better IMHO.

 

[JD Spydo]

I've bought decent plain leather strops along with ALOX compounds, green compound, diamond spray, and even suspended polycrystalline .25 micron diamond for use on basswood strops. I've also made horsebutt leather strops prepared according to some specific instructions. Having said that, I went on a lark and also bought Knives Plus Strop block and it can achieve sharpness very easily and effortlessly. I'm thinking it's because it's supersaturated with compound and maybe that's how it's suppose to work. I've tried the knives plus strop on au8, sv35n, and elmax and I could easily tell the difference in just a few strokes. I thought before that chromium didn't work on "super steels." Fortunately, I was wrong. So I can confidently recommend Knives Plus Strop.

Basswood Strops?? OK I'll admit up front that I'm in no way an expert on strops but that did happen to catch my eye because the part of Missouri that I'm from we do have a significant number of Basswood trees here. Now I've heard of "balsa wood" strops but this is my first time of hearing about Basswood Strops. A little funny sidebar concerning Basswood trees is that seed pod they have is edible according to my local MO Dept of Conservation agent.

So what are the properties of basswood that make it a desirable strop material? The three strops I currently have are "Russian Boar, a homemade leather strop ( made from really rough/crude leather) and one fine grade, slick finished leather strop. Now I do find the Russian Boar to be good on most everything and especially good on straight razors. And please I'm in no way trying to derail this most interesting thread but that is the first time I've ever heard of Basswood being used for stropping material.

The few times I've cut up Basswood trees is that the wood seems to have a lot of the properties similar to that of cottonwood trees.

One last question and all you guys can feel free to chime in>> with all the newer supersteels we have and more and more of them with high vanadium and cobalt contents is it safe to say that diamond compounds and related materials are now the only surefire, effective compounds that would work well with about any of the newer/better blade steels?

 

[Obsessed with Edges]

Regarding basswood strops:

I started using basswood simply by happenstance, because I found it in conveniently-sized pieces for stropping at the local hobby supplies retailer. Balsa and basswood seem to be widely available for woodcrafting & model-building hobbyists and carving enthusiasts, which I assume is why I found it there. I'd originally looked there for some balsa to be used as a strop, which they also carried. I chose basswood over the balsa for stropping, because it's firmer, smoother and tighter-grained than balsa. It's also inexpensive and cut to the perfect size for stropping, in widths ranging from 1-1/2" up to 3" or more, thicknesses up to 1/2" and in lengths of 24" (maybe up to 3-4 ft.). I've mentioned using and liking basswood many times here on the forum; I don't know if that's why it's become more popular here, but maybe so. I have a couple pieces in 24" x 3" x 1/2" size, and a block of it in roughly 'brick size' (7" x 3-3/8" x 1-3/4"), which I assume was sized & sold for craft/carving purposes; I use the edge of that piece with some diamond paste.

Most any smooth and tight-grained wood can be used for stropping. In addition to balsa and basswood, I've used maple and red oak (not so tight-grained, but very firm) similarly. Poplar could work as well, and it's also relatively inexpensive and cut to similar sizes as the hobby basswood, and can usuaully be found at the local home center.


David