Need help with new strops & debating between diamond pray and diamond paste

Joined
Jan 19, 2013
Messages
48
Hi guys!
I need your help. I free hand sharpen my knives on silicon carbide sandpaper attached to glass and sometimes I use my Fallkniven DC stone. The maximum grit I use is 3000. I finish my knives on a hand made strop. I get a mirror edge which grabs free standing hair on my hand which is great but the edge is too polished and dosen't have the bite to initiate the cut.


Because of that, I want to make new strops and load them with diamond spray or diamond paste. I have a few 2 1/4" x 7" glass sheets on which I would glue flexible but thin leather with the smooth side up. I will probably buy balsa wood just to try it out.

My first choice were the Hand American Diamond Sprays but they are expencive, especially with the shipping to Europe (most places 40$ just for shipping), and I don't know if one bottle/grit is enough. Is it worth it?
I found little cheaper all purpose diamond sprays on ebay. Are they any good?

The second option are diamond pastes. I'm scared that they are not agressive enough compared to the spray and that they are thicker and harder to apply to the strop.
7 piece THK 5 gram kits (0.25-5.0 micron) go for 15$ with free shipping on ebay.


Thank you in advance!
 
You could try the compounds you're already using, but on hardwood, balsa, something with less give. Ordinary black emery compound works pretty good for this too, even on leather. I was surprised at the kind of edge I could get working with ordinary compounds on hardwood, using a few drops of mineral oil to turn them into a tacky slurry. Had the best luck with oak, probably due to the larger grain. Made a couple videos a while back on this topic if you're interested.

http://www.youtube.com/watch?v=1nxmn-aJwQY

http://www.youtube.com/watch?v=gfblDsTy-FY

I don't have a ton of experience with diamond compounds but the paste works fine, just give it a chance for the vehicle to dry/soak in a bit. The HA sprays are frequently recommended on the forum. Not sure I'd spring for them unless you're using steel with a high carbide content. My experience might not be typical, but on regular stainless and carbon steels I saw no real glaring advantage over AlumOx based compounds.
 
The differences betweej a quality spray/paste and a cheap one are a direct correltaion to the cost. The cheap stuff contains much less diamond (they purchase it by the karat) and lacks a consistant particle size distributution. If cost is an issue i would email ken and get some of his new Boron Carbide. He offers it in 3 grit sizes. (3k , 5k and 8k respectively) the latter two would be good options for you to try. Pm me if you would like his contact info...
 
West Šenkovec;12677011 said:
Hi guys!
I need your help. I free hand sharpen my knives on silicon carbide sandpaper attached to glass and sometimes I use my Fallkniven DC stone. The maximum grit I use is 3000. I finish my knives on a hand made strop. I get a mirror edge which grabs free standing hair on my hand which is great but the edge is too polished and dosen't have the bite to initiate the cut.
...so your solution is to polish it some more?:confused:

If the diamond spray is too expensive for you, then you have no reason to go with diamond unless you're sharpening ceramic knives. Get a tub of Mother's Mag & Aluminum Polish and use that on your strop instead:thumbup:. Erm, assuming you want less bite, because that will polish your edge more, in case I haven't pointed that out enough:D.
 
+1 to the recommendation for trying any/all compounds on different substrate, like wood, paper over glass/stone, etc. May not necessarily need diamond at all, especially if the steel being stropped isn't especially wear-resistant. Simpler steels respond better to simpler compounds, generally. Harder/more aggressive compound like diamond will be overkill (by over-polishing) on less wear-resistant steels, especially if stropping goes on too long. If going for polished hair-splitting edges, I'd avoid using leather anyway, except for the last finishing touches for cleaning up edge debris/burrs/etc.

Much or most of the 'bite' that's desired in a finished edge should come from the stones, not the strop. Stropping is at it's best when it's used to very gently and elegantly refine and enhance the finished edge from the stones, and not when it's used to change the character of it. It's rare when a leather strop actually adds 'bite' to a previously over-polished edge, UNLESS it's thoughtfully and creatively applied (such as a coarse compound over hard backing, as suggested earlier). Even then, it can sometimes be tricky to get it right. Generally simpler to watch for the desired 'tooth' in your edges while doing the stone work, at which time you STOP and use the strop only to clean up the burrs and other loose debris. If the strop can't finish everything within just a couple minutes' time (or even a few passes), chances are results will begin to degrade, the longer stropping goes on.


David
 
Well im.sure that some mothers metal polish on an old scrap peice of leather will leave a nice dull edge. Same with a green stick of whatever smeared on some scrap leather. Makes an edge look nice but not much else. A quality compound applied correctly after his regular progression will leave a very bitey edge. Ive created bitey edge up around 640,000 grit so how is it that everyone else here manages to dull thier edge everytime they touch a strop?

The only reason a strop will ever degrade an edge is because of either

A) Poor technique
B) Using a compound that is not suitable for sharpening
C) Using too soft or a contaminated substrate.

Proper stropping is just a continuation of the sharpening process.

When i jump from my 30k shapton (.5 micron) i sure dont go to some mothers car polish. I go to .25 Micron diamond or CBN or whatever quality compound i am using that day.
 
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I use the smooth side of 1-1,5 mm thick leather. It's pretty hard because it's glued to a piece of wood and I use light pressure so I don't have the problem of rounding of edges.

Half of the strop has bare leather and the other half has a fine polishing paste.
It's good for polishing the edge after sharpening but it's not agressive enough to bring back the sharpnes after some use. I have the feeling that I need something more agressive. I know that a strop is not a sharpenig stone.

The differences betweej a quality spray/paste and a cheap one are a direct correltaion to the cost. The cheap stuff contains much less diamond (they purchase it by the karat) and lacks a consistant particle size distributution. If cost is an issue i would email ken and get some of his new Boron Carbide. He offers it in 3 grit sizes. (3k , 5k and 8k respectively) the latter two would be good options for you to try. Pm me if you would like his contact info...

I know why it's cheaper in theory, I'm interested if there is some noticeable diference in real life aplications.
I will contact you. Thank you.

...so your solution is to polish it some more?:confused:

If the diamond spray is too expensive for you, then you have no reason to go with diamond unless you're sharpening ceramic knives. Get a tub of Mother's Mag & Aluminum Polish and use that on your strop instead:thumbup:. Erm, assuming you want less bite, because that will polish your edge more, in case I haven't pointed that out enough:D.

The current strop is too smooth. I think with the diamonds it would be more agressive and sharpen or maintain the sharpness without dulling the knife. Or at least slow down the process. I hope you understand what I mean.

It's not too expensive on its own. The spray is 22$ + 40$ for the shipping. The shipping is twice the price of the spray. That's just a waste of money.


..Much or most of the 'bite' that's desired in a finished edge should come from the stones, not the strop. Stropping is at it's best when it's used to very gently and elegantly refine and enhance the finished edge from the stones, and not when it's used to change the character of it. It's rare when a leather strop actually adds 'bite' to a previously over-polished edge, UNLESS it's thoughtfully and creatively applied (such as a coarse compound over hard backing, as suggested earlier)...


David

I understand that and I'm trying to achive that.

The only single reason a strop will ever degrade an edge is because of either

A) Poor technique
B) Using a compound that is not suitable for sharpening
C) Using too soft or a contaminated substrate.

It's B for me. Or no compound. :D
 
Much of what is said re stropping is applicable only to stropping on leather. As for an edge "degrading" on a strop, one would have to define the term a bit more clearly. Even with good technique, stropping on leather will certainly remove edge irregularities that allow the blade to catch better on dense fibrous materials. It might carve/shave/chop better, but will loose drawcutting efficiency. If one is looking for a catchier edge, stropping needs to be approached thoughtfully.

On my Washboard I have successfully (and quickly) refined an edge to a toothy finish from worn/moderately dull, or from overstropped/rounded/polished smooth. Likewise but with more effort and time I have done so using a hardwood lapping board. If you're looking to maintain a coarse edge at its best, diamonds or SIC right off the stone might be optimum, with only a light stropping on plain paper or hard leather with no compound. If you're looking to make a finer "microtoothy" edge and maintain at that level, possibly with less steel removal over time, backhoning on waterstones, jointer stones, or stropping on a Washboard is a good way to go. None of these methods fit the classic definition of a strop, but then if one is looking for a toothier edge you don't really want a classic strop.
 
Well im.sure that some mothers metal polish on an old scrap peice of leather will leave a nice dull edge. Same with a green stick of whatever smeared on some scrap leather. Makes an edge look nice but not much else. A quality compound applied correctly after his regular progression will leave a very bitey edge. Ive created bitey edge up around 640,000 grit so how is it that everyone else here manages to dull thier edge everytime they touch a strop?

The only reason a strop will ever degrade an edge is because of either

A) Poor technique
B) Using a compound that is not suitable for sharpening
C) Using too soft
or a contaminated substrate.

Proper stropping is just a continuation of the sharpening process.

When i jump from my 30k shapton (.5 micron) i sure dont go to some mothers car polish. I go to .25 Micron diamond or CBN or whatever quality compound i am using that day.

This is exactly what I was referring to, and fully in the context of my earlier post (compound too aggressive for the steel, and/or substrate too soft --> overpolishing/rounding of the edge). With a more suitable compound and a firmer substrate, skillful stropping can indeed be done at length, with minimal degradation. It's why I do about 99% of my edge maintenance on strops alone; even then, each session takes maybe a couple minutes or less. This is why I also stated that simpler steels respond better to simpler compounds, in general. A compound that's more suitable to the steel (in aggressiveness) gives some extra leeway before it begins to 'overkill' the edge. When learning stropping technique (which implies learning to know when to stop), that extra headroom in allowable time spent is helpful, without running the risk of doing more harm than good.

David
 
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Leave your knives at 3000 grit and don't strop at all. That should be toothy enough yet still be able to grab a standing hair. Stropping reduces the toothiness, irrespective of materials.
 
Not true at all. What if you strop on a 140 atoma.You dont think that would create a toothy edge.

In theory a 4micron stropping compound and a 4 micron stone will leave an identical scratch pattern. But theres another factor that comes into play at a microscopic level. Burnishing. Which is an entirely new discussion. One that is worth a read over at wicked edge forums if your interested in this kind of level of refinement. Clay Allison has done some pretty extensive studying with no real conclusive data one way or another.

You can create toothy edges with a strop. I have some 15 micron CBN that proves the point quite well.
I also have 640,000 grit edges that feel sticky sharp. But they still feel bitey like a low grit finish does. Not the exact same but not the blunt polished rounded off apex everyone here talks about all the time.
 
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Well im.sure that some mothers metal polish on an old scrap peice of leather will leave a nice dull edge.
Tree-topping(when running the edge along my leg, halfway up the length of the hair away from the skin, the hairs pop off) hairs is dull?:eek:

When i jump from my 30k shapton (.5 micron) i sure dont go to some mothers car polish. I go to .25 Micron diamond or CBN or whatever quality compound i am using that day.
And there's nothing wrong with that.

But the OP mentions price, so I suggested a cheap and easy solution because the Mag Polish is more readily available and so should have a local supplier. Not to mention the hand american and equivalent sprays are roughly $20 per bottle, with the CBN sprays at $45 a bottle.

The abrasive is magnesium oxide with a starting grit of >5 microns, but seems to break down to about 0.5 microns, hence why it seems to be both aggressively fast and leaves a mirror finish. Seriously, you can try it for less than 10 bucks on copy paper.
 
Not true at all. What if you strop on a 140 atoma.You dont think that would create a toothy edge.

In theory a 4micron stropping compound and a 4 micron stone will leave an identical scratch pattern. But theres another factor that comes into play at a microscopic level. Burnishing. Which is an entirely new discussion. One that is worth a read over at wicked edge forums if your interested in this kind of level of refinement. Clay Allison has done some pretty extensive studying with no real conclusive data one way or another.

You can create toothy edges with a strop. I have some 15 micron CBN that proves the point quite well.
I also have 640,000 grit edges that feel sticky sharp. But they still feel bitey like a low grit finish does. Not the exact same but not the blunt polished rounded off apex everyone here talks about all the time.


Stropping on a 140 Atoma will leave you with a burr edge, not a toothy edge.

A 4u abrasive on leather (or any conformable surface) will create a scratch pattern fractions of the size of the same abrasive in a vitreous stone or bonded to a plate. The same 4u abrasive will make a more pronounced scratch pattern yet again if used on a hardwood lapping board. There are variables at every turn.

Even if the edge does not round on the strop, it will become more uniform viewed from the side. This is not desirable for the OP. Even using a larger grit will only prolong the effect - indefinite use will still make a more uniform cutting line and eventually some rounding of the apex becomes a virtual certainty, whether one can readily observe it or not. If the abrasive can sink into the leather to present a more uniform abrading plane, the leather must be compressing somewhat. As it returns to its normal volume, pressure concentrates at the apex, removing a little more steel from the cutting edge than the back-bevel every time its used. Hence the admonishment to strop less and use the stones more.

Burnishing come into play even at the macroscopic level, all that's needed is the right combination of pressure and friction and the absence (or near absence) of abrasive material removal. Meat packer's steels, paper wheels (to some extent), fine ceramic hones (to some extent), even my humble Washboard can produce a burnishing effect. Some of the effects of a smooth steel can be seen with the naked eye.

Probably the best advice to the OP is this:
Leave your knives at 3000 grit and don't strop at all. That should be toothy enough yet still be able to grab a standing hair. Stropping reduces the toothiness, irrespective of materials.

Especially if the 3k stone in question will support some backhoning as a finish step. Keeps the edge toothy without removing a lot of steel. Lightly strop on some paper wrapped around the same stone - not enough pressure to burnish but provides a bit of polish and fine burr removal.

Just my 2c.
 
Well here's a couple of things to consider.

I have customers in Europe and can get a small flat rate box to them that can contain up to 4 bottles of compounds for $24. You can also get fine strops in 1x6" or 2x6" in a flat rate box saving more on both postage and parts.

http://ircalc.usps.com/MailServices...lingDate=9/26/2013&MailingTime=8:00 AM&dv=100

So I've saved you $16+ already :) I sell product , not 'handling'. And this is without tracking which saves you a LOT going to Europe.

Mother's is a polish for chrome. Magnesia is a binder also used in stones. The abrasive component in Mothers is Aluminum oxide. When polishing chrome on a bike / hubcap etc, the consistency is less critical than an edge. It does work, but there are better 'solutions'. I introduced a HARD CORE Mother's user to alumina emulsion at 1 micron and well now he just uses Mothers on his Beloved Harley :) Then he tried 0.3 microns (close enough to 1/4 micron, actually a third micron) and was quite ecstatic with it. He's still holding out at going to 0.050 microns :) These aluminum oxide preparations work better than Mother's because they are designed for edges - far greater particle size consistency yields a better finish. You have this same sort of issue with Chromium oxide - it isn't as finely graded either. Chromium oxide is primarily used for paint pigments and particle size varies a lot. Even my aluminum oxide preparations have a wider variance than my CBN or diamond products. CBN and diamond is bought by the carat (1/5 gram). Aluminum oxide, Silicon Carbide and Chromium oxide is bought by the pound. For this reason, my aluminum oxide products are significantly less expensive.

The formulation plays a critical role. A thick paste or stick doesn't spread as well as an emulsion, spray or properly formulated paste.

You also should understand what you are buying. If your paste has a low concentration, you are paying for the paste not the diamond. If it is inaccurately graded, sometimes you get a product resembling floor sweepings rather than a precision product. You should know how many carats you are buying for your money. Compound bars are notorious for not giving you any idea what's in them. Especially the various green bars out there - usually a mix of Aluminum oxide and some Chromium oxide, both of unknown particle sizes.

Boron carbide is a bit more expensive and a bit better than Aluminum oxide preparations when working with more abrasion resistant steels. Not quite as hard as the vanadium carbides in the more abrasion resistant steels. Here CBN (Cubic Boron Nitride) and diamond preparations excel. Yes they cost more but they work better and last longer too. I have one customer who uses CBN on linen belts and reports getting as much use from loading the belt once as he does from 5 - 10 belts of Aluminum oxide based belts. And then he uses the same belt and reloads! Do the math :) cost per bottle is high. Cost per use is very low.

Strops. IMO a good strop should not be thick and should be hard - even for a convex edge. If you have a strop with give, it is OK for a final finish, but if you do a sequence of strops you get inconsistency and dulling. It should also not 'compete' with the abrasive, letting the abrasive do the work. Here paper thin leather on a firm backing 'rules' - nanocloth and Kangaroo IMO are top choices.

Level of finish - It is useful to think of stones, compounds etc on a continuum rather than dividing into categories. A 4 micron 'strop' and stone are quite similar, the differences being ones of specific particle type and substrate hardness and neutrality. I can go into this in more detail.

Jumping from a 3k finish to a 0.5 micron or 30k finish is just too big of a jump - that's a 10x jump. Consider going to a finer stone or a coarser compound. A 2 micron (8k) strop or 8k stone would be a more useful followup than jumping to a quarter or half micron preparation - either as a stone, stropping compound or a hybrid 8k stone with a 2 micron CBN spray on it. This has some interesting advantages, but that's another topic of discussion.

Hope this helps a bit.

---
Ken
 
Depends on how perfect you want the finish though right Ken?

I just did 60, 45, 10-micron progression before jumping to Mother's Mag Polish and then bare leather on a 1x42 belt sander on a ZT0560 that had a factory edge. The resulting edge could pop hairs easily and did whittle my leg hairs when passing above the skin. Pretty obtuse too at about 20-25 degrees per side. From what I understand, aluminum oxide breaks down. Going to finer AO abrasives just seems to necessitate more steps between the 10 micron belt and the emulsion.

If we're just after simple sharpness, I would think this would work. Plus it seems to get damn sharper when I stick a 0.25 micron diamond spray loaded belt right before the leather.

At this point I think we're just splitting hairs between getting a sharp edge and sticking a flawless mirror polish on it. I feel pretty happy and satisfied when I drop a tomato on the edge and watch it split neatly in half:thumbup:.

But then again, it might be different when you're using power tools:D.
 
Tree-topping(when running the edge along my leg, halfway up the length of the hair away from the skin, the hairs pop off) hairs is dull?:eek:

And there's nothing wrong with that.

But the OP mentions price, so I suggested a cheap and easy solution because the Mag Polish is more readily available and so should have a local supplier. Not to mention the hand american and equivalent sprays are roughly $20 per bottle, with the CBN sprays at $45 a bottle.

The abrasive is magnesium oxide with a starting grit of >5 microns, but seems to break down to about 0.5 microns, hence why it seems to be both aggressively fast and leaves a mirror finish. Seriously, you can try it for less than 10 bucks on copy paper.

That's the level of sharpness I achieve.

20$ per bottle is ok but I refuse paying twice the amount just for shipping.



Well here's a couple of things to consider.

I have customers in Europe and can get a small flat rate box to them that can contain up to 4 bottles of compounds for $24. You can also get fine strops in 1x6" or 2x6" in a flat rate box saving more on both postage and parts.

http://ircalc.usps.com/MailServices...lingDate=9/26/2013&MailingTime=8:00 AM&dv=100

So I've saved you $16+ already :) I sell product , not 'handling'. And this is without tracking which saves you a LOT going to Europe.

Mother's is a polish for chrome. Magnesia is a binder also used in stones. The abrasive component in Mothers is Aluminum oxide. When polishing chrome on a bike / hubcap etc, the consistency is less critical than an edge. It does work, but there are better 'solutions'. I introduced a HARD CORE Mother's user to alumina emulsion at 1 micron and well now he just uses Mothers on his Beloved Harley :) Then he tried 0.3 microns (close enough to 1/4 micron, actually a third micron) and was quite ecstatic with it. He's still holding out at going to 0.050 microns :) These aluminum oxide preparations work better than Mother's because they are designed for edges - far greater particle size consistency yields a better finish. You have this same sort of issue with Chromium oxide - it isn't as finely graded either. Chromium oxide is primarily used for paint pigments and particle size varies a lot. Even my aluminum oxide preparations have a wider variance than my CBN or diamond products. CBN and diamond is bought by the carat (1/5 gram). Aluminum oxide, Silicon Carbide and Chromium oxide is bought by the pound. For this reason, my aluminum oxide products are significantly less expensive.

The formulation plays a critical role. A thick paste or stick doesn't spread as well as an emulsion, spray or properly formulated paste.

You also should understand what you are buying. If your paste has a low concentration, you are paying for the paste not the diamond. If it is inaccurately graded, sometimes you get a product resembling floor sweepings rather than a precision product. You should know how many carats you are buying for your money. Compound bars are notorious for not giving you any idea what's in them. Especially the various green bars out there - usually a mix of Aluminum oxide and some Chromium oxide, both of unknown particle sizes.

Boron carbide is a bit more expensive and a bit better than Aluminum oxide preparations when working with more abrasion resistant steels. Not quite as hard as the vanadium carbides in the more abrasion resistant steels. Here CBN (Cubic Boron Nitride) and diamond preparations excel. Yes they cost more but they work better and last longer too. I have one customer who uses CBN on linen belts and reports getting as much use from loading the belt once as he does from 5 - 10 belts of Aluminum oxide based belts. And then he uses the same belt and reloads! Do the math :) cost per bottle is high. Cost per use is very low.

Strops. IMO a good strop should not be thick and should be hard - even for a convex edge. If you have a strop with give, it is OK for a final finish, but if you do a sequence of strops you get inconsistency and dulling. It should also not 'compete' with the abrasive, letting the abrasive do the work. Here paper thin leather on a firm backing 'rules' - nanocloth and Kangaroo IMO are top choices.

Level of finish - It is useful to think of stones, compounds etc on a continuum rather than dividing into categories. A 4 micron 'strop' and stone are quite similar, the differences being ones of specific particle type and substrate hardness and neutrality. I can go into this in more detail.

Jumping from a 3k finish to a 0.5 micron or 30k finish is just too big of a jump - that's a 10x jump. Consider going to a finer stone or a coarser compound. A 2 micron (8k) strop or 8k stone would be a more useful followup than jumping to a quarter or half micron preparation - either as a stone, stropping compound or a hybrid 8k stone with a 2 micron CBN spray on it. This has some interesting advantages, but that's another topic of discussion.

Hope this helps a bit.

---
Ken

Yes, it was very helpful.

I will probably order one spray to see how it works out. If I'm happy with the result, I will order other grits.
I'm also considering buying a Spydeco UF stone.

Thank you for your responses.
 
You could try the compounds you're already using, but on hardwood, balsa, something with less give. Ordinary black emery compound works pretty good for this too, even on leather. I was surprised at the kind of edge I could get working with ordinary compounds on hardwood, using a few drops of mineral oil to turn them into a tacky slurry. Had the best luck with oak, probably due to the larger grain. Made a couple videos a while back on this topic if you're interested.



I don't have a ton of experience with diamond compounds but the paste works fine, just give it a chance for the vehicle to dry/soak in a bit. The HA sprays are frequently recommended on the forum. Not sure I'd spring for them unless you're using steel with a high carbide content. My experience might not be typical, but on regular stainless and carbon steels I saw no real glaring advantage over AlumOx based compounds.
Could you use the work sharp pro to first sharpen and then use the sandpaper on the edge with the compound or do you have a suggestion for a type of strop with a compound after the blade has already been sharpened by the machine to get the mirror finish....im very new to this any help would be appreciate I'm trying to narrow down the tools I'll need and the specific types and brands I should get ie:for example is there a brand of a strop I could get from amazon
 
If you're looking to maintain a coarse edge at its best, diamonds or SIC right off the stone might be optimum, with only a light stropping on plain paper or hard leather with no compound. If you're looking to make a finer "microtoothy" edge and maintain at that level, possibly with less steel removal over time, backhoning on waterstones, jointer stones, or stropping on a Washboard is a good way to go. None of these methods fit the classic definition of a strop, but then if one is looking for a toothier edge you don't really want a classic strop.

Super interesting, thanks! I've been doing this approach (backhoning very lightly on a water stone in lieu of traditional stropping) without realizing fully what positive effects it was providing.

HH, when you use this approach, assuming just a few super light edge-trailing strokes, is it important to backhone at the exact sharpening angle? Or do you want a slightly lower angle in this case?

I confess, stropping is the most confusing subject in sharpening for me. Everybody I talk to has a different approach. I've tried several: traditional leather, suede with compound, hard balsa block, HH's approach of paper + coarse stone + compound, and now backhoning. Of all of these, and in my limited experience and without any Cliff Stamp-approved scientific testing, the last 2 appeared to get the best results on my knives and did it with the least amount of mess, hassle, gadgets, and farting around with stuff. ;)
 
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