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Strop compounds - New Member
- Thread starter jcmv4792
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Diamond is at least ~3X as hard as any of the usual black/white/green/etc colored compounds, for starters. This means it cuts deeper, therefore leaving somewhat 'coarser' scratches than other compounds of identical particle size. On simpler steels like 1095 and 420/440-variety stainless, diamond would usually be overkill, removing more metal than necessary to accomplish the same end-goal. Diamond is at it's best in refining steels with high vanadium carbide content (S30V, S90V, etc.), because vanadium carbide is harder than any of the black/white/green and others. Cubic boron nitride (CBN) compound is about ~1/2 the hardness of diamond, so it'd work on these steels as well.
At very small particle size of maybe 1µ or less, diamond can more or less be used universally on most any steel. Care still needs to be taken on simpler steels though, because it's very easy to over-polish them with a small-particle compound this aggressive.
For most mainstream steels favored by knife nuts like us, black/white/green is plenty good. In fact, I tend to believe they're usually better-matched to mid-range knife steels from D2 on down, and can produce better results than diamond in most cases, as it's easier to fine-tune results on simpler steels with them. In particular, I really like green compound for 1095, Case CV, Opinel's XC90, 420HC. White works great with these as well, but also for others like Sandvik steels, VG-10, 154CM/ATS-34, 440C, D2 (these all have moderate to higher concentrations of chomium carbides, if you're looking for a commonality). Black also works well for most of those, but starts getting more aggressive with the softer/simpler steels; maybe a little more aggressive than necessary.
David
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I see, s30v s35vn and Elmax are the steels I would be using it on, so it would be worth getting some 1 micron paste then? I have a good amount of s30v three s30vn and a couple Elmax.
That's the other thing there are a lot of different micron pastes so I should not go over 1 then?
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With high-wear steels such as these, diamond will work better. And you shouldn't have to worry if you do go larger than 1µ. Depending on how much you want to refine your edges, they might be useful to you. For example, if you're wanting to mirror-polish your bevels, a tighter descending sequence of grits works better (such as 6µ > 3µ > 1µ).
I emphasized the 1µ as more universal overall, because it's not so large as to be a problem with softer, less wear-resistant steels (1095, etc). The combination of larger particle size and much harder grit can eat up low-wear steels much faster, and it'd be more difficult to fine-tune edges that way. The 1µ is still hard enough to work very quickly on these simpler steels, in spite of it's small grit size.
David
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Ok one last question. Just for reference, where do diamond and boron nitride compound fall in line with the grit count on the stones/polishing tape and normal stropping compound? Right in between?
And how does the scale of microns and grits relate? Sorry I'm sure I could google a lot of this but the advice I find here is very direct and is automatically cross referenced by other members who view this thread, and so far your advice has provided the exact answers I was looking for, much thanks.
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Both diamond and CBN are available in a pretty wide grit range. Particle sizes in microns are about the only way to directly compare anything at all, but differences in hardness and particle shape will affect how each actually performs; often more so than the size. For a given particle size, more angular or 'jagged' particle shapes tend to work more aggressively than other particles which may be more blocky or rounded in shape. Diamond and CBN are both very hard, and usually pretty angular in shape as well. Silicon carbide ('black' compound) is also known to be pretty jagged, almost glass-like in shape, and basically 3rd in hardness behind diamond and CBN. Aluminum oxide (often 'white', but also could be grey/brown/blue/pink) follows silicon carbide in hardness, but is often more blocky or rounded in shape (there's much more variation in shape of AlOx, generally). Green compound is less hard than any of the above, as well as small in size, so it'll work less agressively.
So-called 'grit' ratings are very vague, and often dependent on an individual manufacturer's standards. More often than not, a 'grit' or 'mesh' rating just means a given particle can fit through a hole of a given size, which implies that much smaller particles will also conform to that given 'grit' or 'mesh' rating. This is why an abrasive size specified in microns is somewhat more useful, aside from being aware of the other differences in hardness or shape.
There's also a characteristic of abrasives called 'friability'. This refers to a given abrasive particle's tendency (or not) to fracture and break down in size under use. Silicon carbide and some, but not all, aluminum oxide abrasives are known for this. Manufacturers of aluminum oxide abrasives often deliberately design this into some abrasives, so they start out working aggressively for heavier material removal, and then follow with a higher finish/polish, as the grit breaks down. Diamond and CBN don't generally break down like this, except perhaps under extreme conditions of pressure or heat.
David
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I just got this same strop. My first and only right now. The one side is rough and the other side is smooth. Which compound or emulsion do you recommend for each side?
Thanks!
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The rough, or suede, side usually gets the most aggressive compound. The smooth side gets the least aggressive, to continue the progression from most to least aggressive. I usually use green compound on the suede side and plain leather on the smooth side. The green compound is actually polish, at about .5 microns. The silicates in the smooth leather are even finer.
You can change compounds if you go from finer to coarse. If you start with green, you can change to black. The coarse black will overcome the finer green. Do not go from coarser to finer. You will always have some coarse compound left. The fine cannot overcome the coarse
I make strops. I use green on suede and plain leather after I finish sharpening on ultra fine ceramics. Hope this helps.
You can change compounds if you go from finer to coarse. If you start with green, you can change to black. The coarse black will overcome the finer green. Do not go from coarser to finer. You will always have some coarse compound left. The fine cannot overcome the coarse
I make strops. I use green on suede and plain leather after I finish sharpening on ultra fine ceramics. Hope this helps.
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Agree on the green; always chromium oxide, and usually in the 0.5-1µ range in size. 'White' compounds can be all over the map, however. Different abrasive types (AlOx, silica-based, tin oxide) can all be 'white', but will perform in vastly different ways. Grit sizes of white AlOx alone can cover a very wide range; the 'white rouge' I use is aluminum oxide rated at 2-5µ particle size. So, in other words, there's really no way to know where a 'white' compound fits in a sequence, based on color alone. If buying a white compound as part of a trio of compounds, such as black/white/green, use it according to the maker's/vendor's sequencing guidelines. Otherwise, some experimentation is usually needed to figure out where it fits.
David
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Do you sharpen your convex blades on the ceramics and finish with the strop? That is the big reason for me getting into stops recently. Just acquired some new blades with convex edges. I was thinking about 2 two-sided strops. One with black compound and one a bit more abrasive (if there is any) on the other side, and the other strop with green on one side and bare leather on the other. I want to maintain the edge!
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Among the commonly-used trio of black/white/green compounds, black usually is the most aggressive; the sequence usually goes black -> white -> green (then to bare, if desired). If you're wanting to make and use a couple of two-sided strops, a logical combo would be black/white on the first, and green/bare on the second one. Start at black, and go from there.
Like the 'white' aluminum oxide compounds, there's also a wide grit range of 'black' compounds available. It could be possible to use two different 'black' compounds (of silicon carbide, usually) in descending grit sizes. Sometimes it'll be challenging or difficult to determine the specifics of grit size, or even abrasive type for the black stick/crayon-type compounds, as manufacturers don't always specify or include that info. For most purposes, the standard black -> white -> green sequence is all that's needed anyway.
David
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Im allmost positive that Amazon compound is same as Jewelers Rouge. I am going to look into that.
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Do you have any idea where a 4 micron CBN emulsion would fall in the black - white - green steps?
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CBN at 4µ would likely more aggressive than most of the commonly-used 'black' crayon compounds, mainly just because CBN is considerably harder and will work more aggressively for it's rated size. Some much coarser (larger grit) black compounds could change that; I don't think most of the commonly sold stick compounds will be quite so coarse, however.
Again though, some experimentation with each compound you have will give a better idea as to where each might fit in a sequence. When starting out, and not really knowing where each fits, it's usually best to stick within one abrasive type through the grit sequence (such as all diamond, or all CBN), or just follow mfrs' guidelines in using the black/white/green trio only. That'll make it easier to get the results expected.
David
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Not having used CBN I couldn't say for sure, but most black compounds listed as "black emery" are aluminum oxide in the 20u-30u range. They will work very aggressively on softer steels and as RC climbs closer to 60 they will work a little less aggressively. I would think any 4u grit would be in the range of most mfgs yellow compound - generally about 3-4u and listed for stainless and a bit larger than the more common 1u white - green tends to fall into the .5u range. As mentioned these are all variable, but if pressed to make general statements, that's the common size range.
Silicon carbide is not a common stropping material found in manufactured polishing compounds - loose SiC is generally reserved for tumbling, lapping and cutting when applied to wire - granite cutting for example. Most if not all of the more common manufactured polishing compounds have MSDS sheets that can be found with a bit of digging and these will list the binder and abrasive, though nothing about size distribution or detailed info about abrasive/binder ratios etc.
Edit to add: In my limited experience with the higher wear resistant steels, a diamond lapping film will reliably produce better finish and results than diamond stropping compounds, and is every bit as user friendly if not more so.
Silicon carbide is not a common stropping material found in manufactured polishing compounds - loose SiC is generally reserved for tumbling, lapping and cutting when applied to wire - granite cutting for example. Most if not all of the more common manufactured polishing compounds have MSDS sheets that can be found with a bit of digging and these will list the binder and abrasive, though nothing about size distribution or detailed info about abrasive/binder ratios etc.
Edit to add: In my limited experience with the higher wear resistant steels, a diamond lapping film will reliably produce better finish and results than diamond stropping compounds, and is every bit as user friendly if not more so.
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The black Ryobi 'Emery Buffing Compound' I have is listed at 1-3 microns, as labelled on the tube. It applies much 'coarser', as the hard/waxy binder is very clumpy/chunky; sort of a pain applying to softer surfaces like leather (I use it on paper over glass/wood). Once in use, though, it's very fast in cleaning up the scratches and finishing at near-mirror, more commensurate with it's rated grit size. Reminds me a lot of the 1µ & 3µ diamond pastes from DMT, in that regard.
(HH's post above does remind me, a lot of the black compounds are indeed emery, a.k.a. naturally-occurring aluminum oxide; also known as 'corundum'.)
David
(HH's post above does remind me, a lot of the black compounds are indeed emery, a.k.a. naturally-occurring aluminum oxide; also known as 'corundum'.)
David
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We've covered this a bit already. My Ryobi black is much rougher, as is Sears black and Dico's black, all in the 30u range with assorted particles between maybe 10u and 30u. Pretty sure the term "black emery" is more of a generic term - I cannot imagine too many modern manufacturers getting their AlumOx from natural sources but is possible.
Grits and Microns?
Bark River Knife compounds: black (3,000 grit), green (6,000 grit) and white (12,000 grit) sharpening/buffing compounds.
This is the best "green" (my opinion) that I, have used, goes on so smooth. Koho-Sha Green Rouge Compound is used by tool makers to give a final polish to their tools. It is manufactured from carefully graded 0.5 to 1.5 micron Green Carbide abrasive in a wax base. Koyo-Sha Green K 1 rouge gives a finer polished edge than any buffing compound (my opinion) and helps produce a razor like edge on knives.
Bark River Knife compounds: black (3,000 grit), green (6,000 grit) and white (12,000 grit) sharpening/buffing compounds.
This is the best "green" (my opinion) that I, have used, goes on so smooth. Koho-Sha Green Rouge Compound is used by tool makers to give a final polish to their tools. It is manufactured from carefully graded 0.5 to 1.5 micron Green Carbide abrasive in a wax base. Koyo-Sha Green K 1 rouge gives a finer polished edge than any buffing compound (my opinion) and helps produce a razor like edge on knives.