Stropping wear resistant steels (S30V, S90V, CTS204P, etc)

S

Strauss95

Joined
Dec 17, 2012
Messages
161
Quick question on stropping wear resistant steels such as CTS204P, S35V, etc. Do you find the typical green, white, black compounds work okay for you on leather? I myself notice I get great results on my kitchen knives and 1095 carbon blades, but my super steel folders don't strop back to sharp as easily. I'm assuming it's normal to take more time on the strop with such wear resistant steels?

I just ordered myself a pair of balsa wood strops, that I plan on loading with 1 micron and .5 micron CBN diamond spray. I'm hoping this will provide much better , and more importantly much faster results when stropping my harder steels. Am I on the right track?
 
Personally I limit myself to diamond lapping films for stropping higher Vanadium steels. You can apply super-abrasives to leather or balsa that will cut the steel and the carbides, but in my experience you will get a better result using a diamond film over a hard surface. A single sheet can last a long time in this role with virtually zero maintenance or care - just a drop of mineral oil to prevent loading.

Still, you will be very happy with the set-up you are working on compared to the typical strop strategy with AlumOx.
 
Thanks HH. I was just wondering because I see most people strop with leather loaded with green compound, and most of these people are stropping very hard steels. Lots of rave reviews about the knives plus strop block, and plenty of those reviews are by people using it on high vanadium steels.

Personally I have been using my two Stropman strops, the HD Compact and more recently my Billy strop. I run white and green on the HD compact, and black/white/green/bare smooth side on the Billy. I do get good results when I'm done, but the harder steels require a lot more effort than say 1095 carbon. I'm guessing most of the people that rave about AlumOx loaded on leather when stropping hard steels have never used a diamond compound to compare the results too. If so, I'd imagine we'd have a lot more people suggesting diamond compounds for stropping the harder steels.

The new strop I purchased was the Richmond kit from CKTG, along with an extra balsa strop. I plan on using the two balsa's with 1 and .5 micron CBN, then finish with a few strokes on the bare bovine leather strop. Excited to see the results, and also looking forward to the firm surface the balsa will provide. Even though my current strops work really well on my kitchen knives, I plan on using my new set-up on them since the stropping surface is so much bigger. Should make it go a bit quicker. I like to touch up my knives after preparing a big meal, since I like to keep my edges in the best condition possible.
 
When you try a good, hard leather strop loaded with CBN emulsion on such steels- using light pressure - you realize that all you were doing with traditional compounds was eating away the apex, convexing the bevel and reducing perceived sharpness

Traditional compounds create drag, which promotes increased pressure. CBN emulsions allow the knife to glide smoothly over the leather without the edge indenting into it.
 
Strauss95 said:
Thanks HH. I was just wondering because I see most people strop with leather loaded with green compound, and most of these people are stropping very hard steels. Lots of rave reviews about the knives plus strop block, and plenty of those reviews are by people using it on high vanadium steels.

Personally I have been using my two Stropman strops, the HD Compact and more recently my Billy strop. I run white and green on the HD compact, and black/white/green/bare smooth side on the Billy. I do get good results when I'm done, but the harder steels require a lot more effort than say 1095 carbon. I'm guessing most of the people that rave about AlumOx loaded on leather when stropping hard steels have never used a diamond compound to compare the results too. If so, I'd imagine we'd have a lot more people suggesting diamond compounds for stropping the harder steels.

The new strop I purchased was the Richmond kit from CKTG, along with an extra balsa strop. I plan on using the two balsa's with 1 and .5 micron CBN, then finish with a few strokes on the bare bovine leather strop. Excited to see the results, and also looking forward to the firm surface the balsa will provide. Even though my current strops work really well on my kitchen knives, I plan on using my new set-up on them since the stropping surface is so much bigger. Should make it go a bit quicker. I like to touch up my knives after preparing a big meal, since I like to keep my edges in the best condition possible.
Click to expand...

The harder the strop, the less poorly it will perform on high carbide steels when using traditional abrasives, and that includes stuff like D2 and 440c. I personally do not like even stropping the higher carbide steels, or ones with larger carbides at all, except on paper as a finishing/deburring step. Even when using superabrasives you will have some carbide excavation because the steel will almost always erode away faster than the carbides. Large carbide steels I prefer to leave at a medium finish, and steels with the finer Vanadium carbides I prefer to use a microbevel on diamond plate to make a refined edge, otherwise will leave them at a medium finish as well.

Once you get into steels with Vanadium carbides you really do need a superabrasive (CbN or diamond) to get the most not just from stropping, but any time you want to work the steel to a bright finish. This is why I prefer the films, as I get potentially a very firm surface and the suprerabrasive in one product, and as a very nice bonus they are immune to loading over time. Most of the time I am using a strop or films on these steels is when they are a full convex etc and I have a large surface to cosmetically finish.

You may or may not find CbN or diamond to outperform more traditional abrasives like CrO or AlumOx on your kitchen knives and such, but I doubt you'll find any drawback either. Have fun!
 
HH, so you are saying the harder the strop surface, the better it will perform on the harder steels? If that's the case, I should see better results with the balsa strop compared to my current Stropman leather strops correct? The nice thing about the Richmond strop set-up is, the base itself is a nice hard level surface. So I'm sure I could try some of the films you mention attached to the base itself. Can you provide a link to the specific films you use? My base is 3x11".

My kitchen knives are pretty tough steels. My main knife, the Kohetsu 210mm Gyuto, is Aogami Super (HRC 63-64). My Santoku is SLD steel (HRC 61-62), and my small petty knife is White#2 (HRC 61). These all take a screaming sharp edge on my current strops, I actually think I get the sharpest edges on those out of all of my knives. They get scary sharp.
 
In general, the harder the strop surface up to a point, based mostly on the geometry of the edge grind, the better it will perform. This is especially true on the higher carbide content steels.

If you're getting great edges on your kitchen knives with the current set-up, stick with it...but experiment as well. On higher RC carbon steel I tend to get great results right off the waterstones with a light strop on paper, though for woodworking tools I will strop just a bit with a fine compound as well - as much for cosmetics as anything else.

The outfit I get from mostly is Fiber Instrument Sales, but I generally keep 6" squares as I don't rely on this material too much. A lot of sharpening suppliers will carry the same materials - 3M diamond lapping films - in larger sizes and a variety of micron. I use mine with just a smear of mineral oil.

Take with a grain of salt, this is my opinion - there is no shortage of folk using diamond or CbN spritz and emulsion on leather and getting great results. I found the films did a better job and less fuss.

Martin
 
I use 1.5 CBN spray on balsa wood and get pretty good results with it. I use it on S30V, S35VN, Elmax, M390, D2, 3V, M4, and VG10. I finish on a thin strip of bare leather over a pretty hard surface but the biggest work is done by the balsa and CBN coating.
 
As the steel and carbides are hard you need a bit more pressure to do the work. If you apply elevated pressure on a soft or flexible strop you will tend to round the edge. Balsa is still very soft and springy compared to the steel. I prefer to use something smooth and thin over something stiffer than balsa. I use micron diamond paste on computer photo paper. I use a thin stack of high density paper (a magazine works) under that. I lay the magazine on my pull-out bread board. I store the impregnated photo paper inside the magazine.
 
I use kangaroo leather mounted on aluminum with 4micron and 1micron CBN and they work very well on the S30V, M390, and S110V blades I have. It's amazing how much polish you get with just a few passes.
 
Is there any noticeable performance differences between the CBN spray vs CBN emulsion? Currently I have a tube of 1 micron diamond paste, along with one bottle of .5 micron CBN spray. I'm looking to buy a couple more micron sizes, and trying to pick between the spray or emulsion. I plan on sticking with Ken Schwartz's stuff as far as particular brand goes.
 
I've used the 4 micron CBN emulsion on a 2X72 leather belt run at very slow speeds on CPM 3V, Elmax, M390, S90V and CPM 10V. It worked so much better than the green compound I was using. However, when I moved to a 6 micron diamond compound I experienced much more aggressive results. I don't usually go finer, as I'm looking for a little toothier edge for field knives. The powered belt and relatively light pressure really seem to work well.
 
Personally when using diamond or CBN abrasives I don't see much of a difference between using leather or a harder stropping medium, it may just come down to personal preference. Looking at edges under the microscope I see no evidence of softer substrates cutting the softer steel around the carbides. In my experience they are always abraded pretty evenly. Of course a softer substrate will result in more convexing on a micro level, but that is to be expected.

HSS with exposed carbides, abrasive used was a Suehiro 20k water stone (Aluminum Oxide abrasive).



And here is the same edge finished with DMT 8k then stropped on leather loaded with 0.25u CBN, 0.1u CBN and then .05u diamond.

 
eKretz said:
Personally when using diamond or CBN abrasives I don't see much of a difference between using leather or a harder stropping medium, it may just come down to personal preference. Looking at edges under the microscope I see no evidence of softer substrates cutting the softer steel around the carbides. In my experience they are always abraded pretty evenly. Of course a softer substrate will result in more convexing on a micro level, but that is to be expected.

HSS with exposed carbides, abrasive used was a Suehiro 20k water stone (Aluminum Oxide abrasive).



And here is the same edge finished with DMT 8k then stropped on leather loaded with 0.25u CBN, 0.1u CBN and then .05u diamond.

Click to expand...

Great pics!

In my experience if you had taken the edge right off the 20k waterstone and stropped that, the carbides would still be very visible after - some standing proud and some displaced. The work off the DMT EEF was the big fixer, and over time using the strops for maintenance I would expect to see the similar effect reappear.

The effect is most notable/visible (in my experience) on steels with large Chromium carbides. With the PM steels or steels with carbide sizes in the low single digit to submicron is not as apparent, though same factors in play. If some are falling out, they must have been exposed at some point prior to their anchor failing.

Will still perform well, but in my hands I find best longevity on these steels by not stropping at all or by keeping it to a minimum. What steel is that in your pics?

I observed the abrasive from an 8k Norton waterstone and 4k King both cut tracks across D2 carbides - carbide presence was not apparent off the stone, but also not a 20k stone... The same abrasives also cut across Va carbides, visible after etching but the cut was far more shallow (no pics) than what is visible on the D2 sample.

This is vinegar etched D2
D2_Vinegar_Etch_100x_4_zpsdce7e0ce.jpg
 
That could well be, and another reason maybe I just never see it is that I too always do a bare minimum of stropping, and don't really use it for maintenance on steels that form a lot of carbides.

The steel in the images is M2 HSS, I also have one I made from T8 HSS.

I will test the theory about going from the 20k to loaded strops if you guys would like to see it. Give me a few days.
 
Just an update, so far I am REALLY liking my new compounds along with the balsa wood for stropping. Getting better results, and as one would expect much faster results especially on my Southard in CTS-204P.

The interesting thing is that so far I am liking the Richmond diamond paste more than Ken's CBN spray. The paste I have is 1 micron, where the CBN spray is .5 which makes a big difference, but I haven't gotten any metal deposits on the balsa loaded with the .5 CBN spray? The strop loaded with the 1 micron paste on the other hand is already very black. I know the 1 micron is more coarse so it will remove more metal, but I was expecting to see SOME metal deposits on the balsa with the .5 CBN. Does that sound normal? I've stropped quite a few knives to try them out so I figured I'd see some metal on the strop by now. With my old leather strops loaded with white and green compounds I'd have black metal deposits on both by now.
 
eKretz said:
That could well be, and another reason maybe I just never see it is that I too always do a bare minimum of stropping, and don't really use it for maintenance on steels that form a lot of carbides.

The steel in the images is M2 HSS, I also have one I made from T8 HSS.

I will test the theory about going from the 20k to loaded strops if you guys would like to see it. Give me a few days.
Click to expand...

I'd love to see it, I can only base what I'm seeing on my own experience and that's an aspect I certainly haven't investigated inside out. Any more you can add would be great.

This is an earlier thread that Josh posted up some pics illustrating what I'd been seeing - but have never really sidelit and micrographed. His pics also useful as he was stropping only with superabrasives. Am not sure what steel it was...

http://www.bladeforums.com/forums/s...arpness-Tester/page6?highlight=bess+score#108

I've seen it with 440c, D2, 154cm. Not so much s30v and up, but I also feel I get a better edge not stropping those steels and assumed this effect had something to do with it. I also was able to reduce/eliminate this effect by using 3mil polyester and AlumOx grit (off the 8k Norton) over a Washboard surface, but it also left more pronounced scratch pattern than the stone itself.

Martin
 
Good thread fellas! OP CBN is my go to stuff for all steels. I don't use anything else.
 
Yeah definitely for steels with a lot of carbides I would advise against using the regular compounds like the green, white, black etc. unless you are only doing a few strokes after sharpening on the stones. Diamond plates are the way to go for sharpening these steels if you want the cleanest edge you can get, followed by a light stropping on your strop of choice. If wanting to try maintenance stropping, you definitely need CBN or diamond on your strop IMO.
 
HeavyHanded said:
I'd love to see it, I can only base what I'm seeing on my own experience and that's an aspect I certainly haven't investigated inside out. Any more you can add would be great.

This is an earlier thread that Josh posted up some pics illustrating what I'd been seeing - but have never really sidelit and micrographed. His pics also useful as he was stropping only with superabrasives. Am not sure what steel it was...

http://www.bladeforums.com/forums/s...arpness-Tester/page6?highlight=bess+score#108

I've seen it with 440c, D2, 154cm. Not so much s30v and up, but I also feel I get a better edge not stropping those steels and assumed this effect had something to do with it. I also was able to reduce/eliminate this effect by using 3mil polyester and AlumOx grit (off the 8k Norton) over a Washboard surface, but it also left more pronounced scratch pattern than the stone itself.

Martin
Click to expand...

Interesting. I've seen the same effect as I've shown on the Suehiro 20k when using brand new AlOx lapping films from 9u up to 1u in progression (9u to 5u to 3u to 1u). I will try to get that 20K to strop test done in the next day or two.
 
You must log in or register to reply here.
Back
Top