Progressing from 8 to 0.5 microns?

G

Gautier

Joined
Aug 31, 2006
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Was hoping one of you fellas that's a little more scientific/obsessive compulsive/anal :p about your sharpening could help me out here. I do the majority of my sharpening either freehand or with a semiflexible backing and wet-dry sandpaper(800-2000 grit). Then I finish up on a strop loaded with jeweler's rouge(red).
Now, by looking at a few charts online it seems that the sandpaper and black hard arkansas stone are about the same as far as particle size, 8 microns. Red jeweler's rouge seems to range between 1.5 and 0.5 microns from what I can gather.
So, my question is, by sharpening like I have been am I skipping a crucial step? It just seems to me that making the leap from 8 microns to 0.5 is going to somehow leave me with a less polished edge. Granted, I can whittle hairs with the edges I put on after I do the first two or three sharpenings on a new blade and get it reprofiled to my liking. I'm wondering if I could be getting sharper edges though? Or maybe longer lasting edges? Any advice or info would be appreciated.


Gautier
 
yes, the leap is to great and your edge could be sharper. For example once I get my edge reprofiled with diamond stones I move to my spyderco stones which are 15,6,and 3 micron partical size and then on to my strop, 3 of them starting a 1 micron then moving to 0.5 and finishing with 0.25. The edge when finished looks like a mirror and splits hair with the lightest touch. Red jeweler's rouge is not 1.5 to .5 microns because green jeweler's rouge is 3 micron so if I had to guess I would say its more like 5-8 microns or greater. Sand paper works ok but I find ceramic stones to put a finer/sharper edge on blades, I have sharpened free hand for a long time and if I could give any good advise this would be it.

DMT stones for reprofiling
spyderco stones for sharpening
diamond paste for stroping

P.S. 0.5 micron is about 50,000 grit
 
The problem with comparing grit size and micron size is that there is not an exact comparison. If you pull up many charts you will see some stating 1000 grit as 2 micron, others state it as 7 micron. The problem is that the industry standards on abrasives allows for a great range of size. In general abrasives, 1000 grit is allowed to range from 23 micron to 2 micron. So if you are selling sandpaper, and you want to say how fine it is, you call it 2 micron. If you are polishing mirrors or gemstones, where the difference will clearly show, you hit a sampling average and call it 7 micron. In polishes, 1 micron is 14,000 mesh, .5 micron is 50,000 mesh, and .25 micron is 100,000 mesh ( it is not always linear as many believe).
Red rouge is the finest of rouges, green is next. However, the particle size can be ground to any size the manufacturer wants. Course red iron oxide is called crocus, the finer grades are called rouge.The finer the grind and the closer the tolerances, the more costly the final abrasive. Red rouge usually runs from 3.5 to 5 microns. It polishes slightly smoother than green rouge (chromium oxide) because of certain molecular differences. Green rouge is often claimed to be 1 micron or less, but this is usually found to be the minimum size, not the average, and surely not near the maximum. If grit size alone was the only thing that mattered, alumina A and alumina B would be the best. "A" is .3 micron, and "B" is .05 micron. Unfortunately, the compound often tends to ball up into larger sizes when polishing steel.

The way to deal with all this is to buy the best quality polishing compound you can, and if possible ask for a compositional analysis of the % of abrasive ( some green compounds only have 5% chromium oxide while others have 90%) and a grit range analysis. Buying from a major supplier is also a good thing. The cheapie (read Ebay) sellers are often selling Chinese abrasives and....well enough say - CHINA.

Hope this helps sort out a conundrum.
Stacy
 
My preference is to go in increments of two, doubling the grit at each step. Thus 1k 2k 4k 8k 16k then CRO or half micron diamond paste. I like starting off with DMT plates (XXC if I don't have a flat edge) for the lower grits. Of course comparing grits unless you stay in a single series is very approximate, since everyone uses different scales, grade more or less precisely, etc. Comparing different particles - aluminum oxide vs diamond is difficult too and the results vary with different steels etc. If you go from a 1k surface to a cro (half micron) particle, it will be sharper but a more refined edge where the scratch pattern from each grit is completely removed before advancing to the next grit is ideal and produces a better edge IMO. I find substituting a 12k stone or even some 10k stones for a 16k stone is fine, but this gets into other charateristics and might get more confusing. I rarely go past half micron to either quarter or tenth micron (diamond pastes) as the results exceed the need for the task the knife is used for. It is fun though.

---
Ken
 
knifenut1013 said:
yes, the leap is to great and your edge could be sharper.
...

DMT stones for reprofiling
spyderco stones for sharpening
diamond paste for stroping
Click to expand...


I've been having some dissatisfaction with my Sharpmaker and my Spyderco Endura Wave 4 straight edge knife. I have a Byrd Cara Cara and a SOG Flash II and both easily pass the paper cutting test new out of the box.

But my USED Endura Wave 4 (mostly used for cutting open consumer boxes) can't even pass the paper test, nevermind whittle hairs.

What EXACTLY would you recommend here?

Right now I've back-bevelled at 30 degrees using the Sharpmaker and primary edge is 40 degress. I tried primary @30 degrees and for some reason @40 degrees does better with the paper. Very frustrating. It still can't pass the 'paper test'. VG-10 SS.

What type of diamond stone and grit would you recommend in this instance?

What is diamond paste? Does it differ from red rouge/green rouge? Or are these diamond pastes?

And in your post are you saying that you have THREE separate strops and you have differing variations of jeweler's rouge and that you use all three?

Thanks in advance.
 
ifilef said:
I've been having some dissatisfaction with my Sharpmaker and my Spyderco Endura Wave 4 straight edge knife. I have a Byrd Cara Cara and a SOG Flash II and both easily pass the paper cutting test new out of the box.

But my USED Endura Wave 4 (mostly used for cutting open consumer boxes) can't even pass the paper test, nevermind whittle hairs.

What EXACTLY would you recommend here?

Right now I've back-bevelled at 30 degrees using the Sharpmaker and primary edge is 40 degress. I tried primary @30 degrees and for some reason @40 degrees does better with the paper. Very frustrating. It still can't pass the 'paper test'. VG-10 SS.

What type of diamond stone and grit would you recommend in this instance?

What is diamond paste? Does it differ from red rouge/green rouge? Or are these diamond pastes?

And in your post are you saying that you have THREE separate strops and you have differing variations of jeweler's rouge and that you use all three?

Thanks in advance.
Click to expand...
Diamond paste goes upto 1/4 micron, chromium oxide(green stuff) goes upto 1/2 micron, you shoulda be able to pass a paper cut test without stropping, do the sharpie marker test, mark the blade with the marker at the edge and sharpen at 30degrees, if the edge still is marked, that means you may need to reprofile the blade thinner for a 30degree edge. What i'm guessing is that with a 30degree edge, you are not sharpening the edge yet, your blade is too obtuse, or it may be that there is a burr.
 
Roger999 said:
Diamond paste goes upto 1/4 micron, chromium oxide(green stuff) goes upto 1/2 micron, you shoulda be able to pass a paper cut test without stropping, do the sharpie marker test, mark the blade with the marker at the edge and sharpen at 30degrees, if the edge still is marked, that means you may need to reprofile the blade thinner for a 30degree edge. What i'm guessing is that with a 30degree edge, you are not sharpening the edge yet, your blade is too obtuse, or it may be that there is a burr.
Click to expand...

So, what is the difference between diamond paste and green CrO and rouge?
I guess that I''m back to my original question.

What do you define to be the edge? Where do I place the marker? On the actual cutting edge or on the side where I guess the 'beveling' is discernible?

If blade should be able to pass paper test w/o stropping, then these pastes are irrelevant in a sense?

So, what purpose does the strop and paste serve besides eliminate irregularities or burrs? To make it 'sharper' beyond belief so that one can 'whittle' a human hair?

BTW, I have yet to be able to discern a 'burr' with my fingernail. do you discern it with your nail or the tip of finger? Can one actually 'see' a burr with the naked eye?

sorry, newbie. :D
 
Diamond paste is more aggressive, and costs more. In addition to the abrasive, you should also consider "feel" - you may like the way one compound feels versus another compound (or maybe I'm just picky).

Marker on the bevel - so you can see where/what you have sharpened. Get a loupe of around 10X-15X, and you can really see what is going on better if you have some magnification. One method is to get close to a light source and try to see if there are any reflections at all coming off the edge - usually you can see problems by seeing tiny reflections at the edge.

There is no right or wrong - some swear by water stones, some by india stones, some by belt grinders, some by freehand and some by jig machines. Some strop every knife and some strop none. Some use different methods for different steels, and some want the same edge on all. Some insist one gets a knife sharper than the other, or other variation on that theme. Lots of good opinions can be found here by reading old posts. I think they can all get a knife plenty sharp if done right.

I think to do it right you have to try out different methods for yourself, keep reading about them all here, and make your own mind up.
 
ifilef said:
...I have yet to be able to discern a 'burr' with my fingernail. do you discern it with your nail or the tip of finger? Can one actually 'see' a burr with the naked eye?...
Click to expand...

You can feel a burr with your fingernail, if the burr is large enough. The burr developes on the side of the blade opposite the side being sharpened. With your fingernail, scratch the bevel toward (from spine to edge) the edge and see if you can feel a "lip" or a slight "catch" just before your nail falls off the edge. You can also take a sharp pin or needle and do the same thing. Hope this helps.
 
Thanks for your comments, all.

I do have a medium India Stone, which I have used for trigger jobs on S&W revolvers.

Perhaps I should start with that, but then I would have to free-hand.
 
Do you guys ever experiment with other polishes? I have lots of .5 micron cerium oxide and tin oxide as well as chrome oxide and diamond that I use to polish gemstones. I've always felt that using diamond to polish anything but the hardest materials was kind of a waste. Is there really an advantage to the diamond over, say, cerium which is pretty hard?
 
firebert said:
Do you guys ever experiment with other polishes? I have lots of .5 micron cerium oxide and tin oxide as well as chrome oxide and diamond that I use to polish gemstones. I've always felt that using diamond to polish anything but the hardest materials was kind of a waste. Is there really an advantage to the diamond over, say, cerium which is pretty hard?
Click to expand...


they work faster, polish better, and will leave a sharper polished edge.
 
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