stropping with diamond paste and spray

[Andrew Pitonyak]

I have owned diamond paste for many years and have still not touched it. I just received some 1/2 micron DMT diamond spray.

In this post, Derek has a link to his site. He compares Green rouge and Diamond paste. He did not like the feel of the diamond paste, but, his process included oily the stop with mineral oil before applying the diamond paste (if I remember correctly). He eventually just stopped using the diamond paste and is using the Green rouge.
https://sawmillcreek.org/showthread....-diamond-paste

I was thinking about making some strops to try the diamond spray and then also try the diamond paste. I expect the same results with the diamond paste as Derek, but, what should i use as my strop material?

I have leather, I can use the rough side or the smooth side. I do not know if it matters, I usually use the smooth side for stropping (I am not super experienced with stropping). I strop knives on my worksharp knife sharpener and it does a pretty good job.

I often see people talking about using wood as the strop. Does it matter if I use a soft wood such as Balsa or Bass Wood, or something harder such as MDF or maple.

I am particularly interested in anyone who has used the diamond spray as a strop.

[John K Jordan]

...
I often see people talking about using wood as the strop. Does it matter if I use a soft wood such as Balsa or Bass Wood, or something harder such as MDF or maple.

I use MDF to strop my lathe skew chisels. It works very well with the stick of green or yellow compound or the Tormek honing paste. Since the MDF surface is usually too smooth to hold the compound I first resaw it on the bandsaw to get rougher surfaces. That the compound I rub into the surface turns black with use proves it is doing the job. Just a few swipes and the skew chisels are shaving sharp.

I don't have experience using this method for traditional chisels and plane irons.

JKJ

[Jim Matthews]

I have a trio of Diamond Paste grits.
I've tried it with a piece of Richlite, which is a paper product impregnated with a resin under presure.

The resulting surface is very hard, and smooth.

With diamond paste, the finest grit seems to impart additional polish to honed edges.

It does not reliably remove a wire edge, where a hard leather strop does.

I've had better results using Flitz metal polish on the Richlite "strop" as the carrier is a little sticky.

[ken hatch]

The problem with diamonds as a finish medium is the type of scratches left by diamonds. Diamonds leave sharp sided scratches which is great for shine but not so good for edge durability. YMMV but an oiled hard leather strop is about as good as you can get for a finish strop. It doesn't make the tool shine but can help remove any left over burr from the finish stone.

ken

[Andrew Pitonyak]

What is stropping?

Iwill start with “what is stropping?” One definition is realigningthe deformed apex with things such as a round rod (carbide, ceramic,steel) or flat surface (leather, wood, etc).
Anotherdefinition is closer to sharpening since it includes the removal ofmetal with abrasive compounds or diamonds on a flat surface. Withreally fine abrasives (<= 1 micro maybe), this is usually calledstropping.
Theresearch I reference below indicates that using a steel does indeedremove metal, so perhaps it is all part of definition 2.

Material?
Fromwhat I can tell for stop material, since I have been trying toresearch it…
Ahard substrate is great for a flat grind and you can do convex edgeson a hard surface, a softer surface is easier to use on a convexgrind -- and an advantage on a irregularly shaped surfaces.
Ifyou use a (water) stone, stones that generate more mud provide asofter surface with a mud 'cushion' and work best for irregularsurfaces. A harder surfaces / stone, Shapton Pro for example, arebetter where the angle variation is kept to a minimum - like straightrazors. I have observed that even the factor edge often varies fromknife makers that hand sharpen on belts (Case Cutler for certain, andbased on the blades I see from the factory lately, I also assumeBuck)
Alsofrom what I can tell, a coarser grit is less particular about thematerial; for example, balsa, copy paper and cow hide. The finestleather seems to be Kangaroo followed by Horse. I have no idea how touse “paper” as a backing material, seems wrong to me, but I didnot explore this.
Apparentlythe Japanese knife makers like to use paper wheels to polish theiredges. I am not looking to get a powered buffing wheel.

I have seen comments that they might prefer a thing leather on a hard backing when using leather. Some preference to Kangaroo might be because it is thinner (in general) than other hides. I don't know one way or another.

Sharpening Research
Ifyou want to find a bunch of research related to sharpening. I thinkthat it is a personal blog site, so I do not think that I can post adirect link, but, if you search for scienceofsharp you will find it.
Muchof his research is related to razors and he likes to use Denim tostrop his razors.
Hereare some random facts:

1. Thesize of metal chips increases with grit size.
2. Therate of metal removal somewhat increases with abrasive size, withsome exceptions.
3. Theinteraction of a grit particle with a metal surface is called“single-grain grinding”.
4. Thereare three modes of “single-grain grinding” sharpening (fromR.S, Hahn, 1962) generally characterized asrubbing, ploughing, andchip formation. I won’tbother with what these mean, if you care enough, go here
5. Abrochure from Pace Technologies shows that the measured surfaceroughness on steel for a range of silicon carbide grit papers. Afterpolishing in random directions, their data show that 15.3 micronparticles produced a roughness of 0.11 microns, less than 1% of theparticle size. We usually sharpen in a single (mostly) direction andit is assumed that this will produce “more roughness”.
6. Thereis an article on the abrasion rate versus grit where he shows thatthe Shapton Glass 2k (about 7.35 micron), he measured an averageremoval rate of only 0.02 microns per pass across the stone withscratches up to 0.5 microns deep suggesting that most of thegrit-steel interactions are simply rubbing, ploughing, andburnishing. Burnishing seems to strongly affect the final surface.

Now,back to stropping. He claims the following:
Edge-trailingand edge-leading strokes on a hard, flat abrasive hone lead toentirely different processes for apex formation and refinement. Edgetrailing (stropping) stroke allows a keener apex to form by avoidingthe micro-chipping that occurs in edge-leading strokes. However,the edge-trailing stroke can lead to the formation of a foil-burrwhile the micro-chipping that characterizes an edge-leading strokegenerally limits the formation of a foil-burr.
Theuse of a compressible substrate (a strop, and I, Andrew, assumethings such as leather) produces micro-convexity and can avoid theformation of the foil-burr that is usually produced when performingedge-trailing strokes on an in-compressible substrate. Thismicro-convexity typically improves keenness and apex uniformity.
Theamount of micro-convexity is determined primarily by the choice ofstrop material. Partial or incomplete micro-convexing of the apexcan produce a foil-burr; for example, using 0.25 micron diamond onleather. The stropping requires only a few strokes, more strokes (upto hundreds of strokes) has minimal additional impact.
More Random Stuff
About10 years ago, someone claimed that if they stropped their knife with0.3 micron chromium oxide after 1 micron diamond spray that the bladefelt less sharp. It was suggested by another that if he had done itright, then he had simply removed the small serrations in the bladeso that removed the “bite” but it was probably sharper; nice forshaving, worse for cutting rope, and not sure with respect to apocket knife or chisel.
Ido have diamond paste that I purchased from eBay many years ago. Ihalf expect this stuff to be garbage. I recently purchased 1/2 microndiamond spray from DMT, and I expect that to be decent stuff. Iprobably need to use something else before the 1/2 micron spray to beeffective. In other words, it is too far a jump from my stones to thespray probably.
TheXF DMT is 9 microns. The XXF DMT plate is 3 microns. I have both. Ialso have water stones and Arkansas stones. On the bladeforums, theyseem to like using MDF for their paste

[Andrew Pitonyak]

The problem with diamonds as a finish medium is the type of scratches left by diamonds. Diamonds leave sharp sided scratches which is great for shine but not so good for edge durability. YMMV but an oiled hard leather strop is about as good as you can get for a finish strop. It doesn't make the tool shine but can help remove any left over burr from the finish stone.

Part of this is related to what I choose to sharpen; for example, sometimes a ragged edge helps with a knife's edge. Also, there is some concern that if you sharpen with the wrong medium you can get carbide tear-out. If this happens, then you can have a "sharper" edge, but it dulls faster because the carbides have been ripped out. Is this true? I have no idea. If this is a concern, then they suggest stropping with something that can actually cut / abrade the carbides.

I cannot help but wonder if CBN (Cubic Boron Nitride) particles leave the same pattern as the Diamonds. CBN is almost as has hard as diamond.

I don't think that my woodworking tools use super-steel and I only have one knife that uses it so perhaps none of this matters, but, I wanted to try the diamond spray to see if it seems to produce an edge that I like. The next question is then, on what should I put the diamond spray.