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A Comparison of Diamond Grit Vs Green Rouge

Derek Cohen has done a Comparison of Diamond Grit vs Green Rouge. It is great to see interest in diamond spreading, even though this review does not come out positive for diamond grit.

For some background, Derek Cohen is in my opinion one of the great woodworkers on the net.  He shares his methods and encourages others.  He does amazing work.  He is one of a small handful of influences that brought me into tool making.  His reviews are superb, his craftsmanship, breadth of knowledge and innovation set him with the very best.  I have copied more than one of his designs.  Blatantly copied.  I consider him a mentor, even though we have never met.

From my own experimentation with diamond grit for sharpening, I find I have to agree with his results, but not the experiment itself.  The problem is that he used Veritas green rouge (0.5 microns) and compared it to 0.5 micron diamond paste that he got off of eBay a few years back.   Unfair that.

I have a small collection of green rouge.  Several are quite inferior for sharpening.  The Lee Vally is my favorite.  It does a superb job, no lie.  The diamond grit however is the poor variable here.  There are a couple of different crystal structures that will give varied results, and the grading of size is always an issue.  When they say 0.5 micron, that could mean it was graded a bunch of different ways.   For example it could be graded from 0.0 to 1.0 microns.  It could also be graded  from 0.4 to 0.6 microns.   The 0 to 1.0 will give a maximum grit size of 1.0 and the0.4 to 0.6 will give a maximum grit size of 0.6  nearly half the size.  The 0 to 1.0 will be cheaper as well, so there are good odds that this comparison is literally the best of one class of grit vs the worst of another.   Additionally the physical properties of top grade grit in green rouge tends to control grit size.  More of the grit will be at about 0.5.

Despite my complaints, I think his observations are going to be the truth.  Grit size for grit size, I suspect that diamond will make for a rougher finish.  Diamonds cut, they do less pushing and scraping.  This is going to leave a difference in finish.  A smooth finish at a particular grit size will be better than a rough finish.  The advantage of green rouge is that it is fairly inexpensive, consistent and for the size of grit, reasonably fast.  It will also leave a mirror finish.   The advantage that diamond has is long wear, speed and the ability to sharpen the harder and more durable modern steels easily.

I would rather he compared best to best for stropping purposes.  If the experiment were repeated using 0.0 to 0.25 micron diamond paste, he would get a very different outcome.   I think he would find that the diamond was, despite being a finer grit, still quite a bit faster.  While it will still leave a misty finish instead of a mirror finish, it will cut quite smoothly.   I really need to send him a sample of some good diamond grit.

Bob

9 comments to A Comparison of Diamond Grit Vs Green Rouge

  • Bob,

    I have a strop with Beta Diamond Products’ 1/2 micron diamond paste on one side and, on the other side, Veritas green rouge (there’s that “jumbo shrimp” thing again). After a couple years using this setup, but without serious controlled examination, I note the diamond paste definitely cuts faster than the Veritas stuff but I don’t find a functional difference in the final edge.

    When I just want to delicately finish off a nice edge, I usually use the Veritas. If I am concerned about preserving edge geometry (avoiding too much rounding), I use the diamond.

    Two excellent products.

    Rob Porcaro

  • I will have to contact Beta. I am always looking for good suppliers to pass on information about.

    Bob

  • Skip J.

    Interesting thread here Bob.

    I am currently using 40 to 60 grit on my medium DMT stone and 10 to 20 grit on my DMT fine stone to recharge both of them. Works like a charm!

    I remember your instructions call for an extra lapping plate for removing wire edges and an extra plate for touch-up with the 0 grit. So if I use the 0 grit on the leather strop, I don’t need an extra 0 grit lapping plate?????

    I have some gold “rouge” I was going to use on the leather strop almost exactly as Rob describes above, but he does not see a functional difference. And I don’t think I’m far enough along yet to discriminate between the two types of grits.

    Based on your comments here – I now plan to charge the strop with 0 to 0.5 grit.

    Skip

  • The strop that I sent you, Skip, is already massively charged with 0.0 to 0.25 micron diamond grit. It should be ready to go.

    Bob

  • Skip J.

    Thanks Bob – I’m glad we had this conversation!

    Skip

  • Ben R.

    I did some research on the Lee Valley Veritas honing compound, and it claims that it is 0.5 micron Chromium oxide. I contacted the manufacturer of the compound, Formax, and discovered that the bar is only 20-30% chromium oxide, 60-70% aluminum oxide, plus a few other ingredients.

    I’m a straight razor user, and the difference between pure chromium oxide and the veritas bar is huge. It’s the difference between a super smooth shave and a tougher one.

    If you’re interested, I did a better write-up on the Veritas bar here:

    http://www.straightrazorplace.com/forums/basic-honing/28088-consumer-alert-chromium-oxide-bars-not.html

    Hand American sells pure chromium oxide and it’s much better than the veritas. I have no affiliation with Hand American.

    I also use .25 micron diamond spray, and find it yields a great shave. Sharper than the chromium oxide, but also harsher. When considering diamond for sharpening, it matters if it’s monocrystalline or polycrystalline. Mono is more durable, but the poly is friable and breaks down in to smaller particles as it is used, leaving a finer finish as a result.

  • Good data and research there, Ben! Thanks for the feedback and information on your link! Now if I can just find out the content of my Yellowstone Bar.

    Bob

  • Wayne Preston

    I have been using a simple jewelers rouge for years and feel like I need to step it up. Where can I buy any of these products. I also have read that I need for my strop to be the rough side of the leather…

    Thanks,

    Wayne

  • very nice and informative blog.. Diamond grit is always good to use..

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