What's the deal with polished edges?

[jackknifeh]

I take my CF zdp189 Stretch II up the grit sized then to a CrO loaded strop. It's nice for certian cuts and the wow factor . I also carry a Salt I sharpened only to a 1000 or 2000 grit. It gives a little bite when you have to cut something like rubber hoses.

If I sharpen my friends knives I usually only go up to an 800 or 1200 grit unless they really want a polished edge. This gives a good edge for most users. I guess mainly it's personal preference.

Kev.

Speaking of grits. There seems to be a vast difference in the numbers used depending on the type of stones. I use an Edge Pro sharpener and stones that came with it are 120, 220, 320, 600 and 1000 grits. I think the 320 would be considered medium. These are water stones. Then there are Japanese water stones. A medium Japanese water stone may be 1000 grit and a fine would be 6000 grit I think. I really don't know much about this because of limited experience with different stones. I've used Arkansas stones all my life and DMT stones in recent years. Both just call their stones coarse, med, fine, etc. but DMT does provide grit numbers. I know the type of edge and polish level I get with the Edge Pro stones because I've been paying more attention lately as I learn more about sharpening. Still no expert though.

When communicating with a variety of people like here I'd like to understand what each person means when mentioning a certain grit number. Numbers are only a reference afterall. Example: 32 deg. F and 0 deg. C are both the freezing temperature of water and feels the same when you walk outside (or in the living room if heater is broken).

Is there a chart or something that lists different types of stones (arkansas, water, diamond, etc.) and their grit levels and how they compare to each other?

Back to subject. My understanding about polished bevels is they glide through material like wood easier than a very scratchy bevel. Doesn't a smooth piece of paper slide across wood easier than a piece of sandpaper? How noticable this is in every day use is the question. I did some whittling with two knives. One polished, the other not. Edge angles were the same, VG-10 steel. I could tell a difference only because I was thinking about it. Even though the difference wasn't that great for me I follow the theory believing I'll benefit from the knowledge even when not thinking about it. I polish ALL bevels except the very edge IF I want a toothy edge. Then, after sharpening a knife to a keen polished edge I'll raise the angle 3 - 4 degrees and sharpen a very small bevel with a 220 stone for a toothy edge if that's what I want. If not I leave it alone or i may put a higher angle polished edge on the blade just to toughen up the edge.

Jack

[chuck_roxas45]

Hey Jack I saw this posted in another forum. Here it is for what it's worth.

[IMG] Uploaded with ImageShack.us[/IMG]

[jackknifeh]

Thanks Chuck,

That is exactly what I was thinking about and hoping for. I was talking to Ben, the EP inventor and he made a comparison concerning the stones he sells to Japanese water stones about grit differences. The chart matches what he told me approximately at least because I don't remember the exact numbers he used. I just remember his products equaled the 6000 Japanese water stone grit.

Hopefully people on this forum and others who aren't in the same room when talking can get a better idea of what tools the other guy is using and be able to equate that to what they use. That's what I'm hoping for.

Thanks again,
Jack

[chuck_roxas45]

Anytime Jack.

I wonder what the 6k polish tape of the EP is equivalent to.

[unit]

A couple thoughts regarding the current conversation:

In assessing abrasives you must be diligent in understanding if they are reported in grit, grain, mesh, sieve, etc. Some reporting methods are similar, some are not.

Another set of concepts is "break in" and "break out". Some (many) mediums will start out a bit more abrasive and inconsistent prior to break in. Over time they behave more consistently, give more uniform results, and generally behave like a finer abrasive.

Some people try to speed results by using more pressure. This is a really bad idea for some mediums as it induces "break out" where abrasives leave the surface and start rolling around and randomly gouging your work (the damage to the media is obvious, but it also damages your results). Obviously using stones that form a slurry are supposed to do this...this illustrates one difference between media types dealing with angularity.

Another point is that the chart should be used as an approximation since the data in the columns is not all from that same source. If you stay in a column, you will be OK, but when you start comparing manufacturers you are going to have a bit of difficulty since (presumably) the testing methods are not consistent for all manufactures. One GLARING example of inconsistency is the Spyderco uf media which is reported as 7 micron on this chart. It tends to polish as good or better than the DMT EEF (3 micron).

There is a whole other discussion regarding testing of edge holding relative to the media used to produce the edge. There are some surprising reports out there, and since my findings are pretty subjective at this point, I will keep them to myself. There are some people out there that spend a LOT of time working with this stuff.

[jackknifeh]

Anytime Jack.

I wonder what the 6k polish tape of the EP is equivalent to.

I don't know. I don't have anything over 3000. I don't even use that too much. I plan to in the future though attempting to get even more of a mirror polishing to the edge. For me I'm still in the learning phase with the tapes. According to Ben they completely replace a strop which I still use. I'm used to it and a few seconds with it does wonders to any edge I have gotten with any sharpener including the EP which are already good. To use the tapes instead of a strop I think the secret is to pull the tapes across the edge instead of pushing it. You won't cut the tape that way either. Also, my patience needs to improve because the tapes remove so little metal with each stroke that more and more are needed I'm sure. I'm going to get it though. I also had problems with the ceramic steel that came with the Edge Pro set. I used it like in the videos and a real sharp edge became very dull. I gave up but one day picked it up and just held it like I always have held a steel without sitting it on a table. This worked for me. It must have been just the angle I was holding the knife at I guess. I still don't like it for putting a final edge on a knife but do like it to quickly put an acceptable edge on a barely dull knife during use. The only thing I've truely learned in life is there is no end to learning.

Jack

[chuck_roxas45]

I don't know. I don't have anything over 3000. I don't even use that too much. I plan to in the future though attempting to get even more of a mirror polishing to the edge. For me I'm still in the learning phase with the tapes. According to Ben they completely replace a strop which I still use. I'm used to it and a few seconds with it does wonders to any edge I have gotten with any sharpener including the EP which are already good. To use the tapes instead of a strop I think the secret is to pull the tapes across the edge instead of pushing it. You won't cut the tape that way either. Also, my patience needs to improve because the tapes remove so little metal with each stroke that more and more are needed I'm sure. I'm going to get it though. I also had problems with the ceramic steel that came with the Edge Pro set. I used it like in the videos and a real sharp edge became very dull. I gave up but one day picked it up and just held it like I always have held a steel without sitting it on a table. This worked for me. It must have been just the angle I was holding the knife at I guess. I still don't like it for putting a final edge on a knife but do like it to quickly put an acceptable edge on a barely dull knife during use. The only thing I've truely learned in life is there is no end to learning.

Jack

I kinda like how the steel works. I sharpened my POS kitchen knives up to the 600 stone and steeled it like in the video. It did make it noticeably sharper(paper slice test).

I am also experimenting with polished bevels. Here is one of my early attempts. Far from perfect but I'm really quite happy with my progress so far. It is a never ending learning experience.

[IMG][/IMG]

[jackknifeh]

A couple thoughts regarding the current conversation:

In assessing abrasives you must be diligent in understanding if they are reported in grit, grain, mesh, sieve, etc. Some reporting methods are similar, some are not.

Another set of concepts is "break in" and "break out". Some (many) mediums will start out a bit more abrasive and inconsistent prior to break in. Over time they behave more consistently, give more uniform results, and generally behave like a finer abrasive.

Some people try to speed results by using more pressure. This is a really bad idea for some mediums as it induces "break out" where abrasives leave the surface and start rolling around and randomly gouging your work (the damage to the media is obvious, but it also damages your results). Obviously using stones that form a slurry are supposed to do this...this illustrates one difference between media types.

Another point is that the chart should be used as an approximation since the data in the columns is not all from that same source. If you stay in a column, you will be OK, but when you start comparing manufacturers you are going to have a bit of difficulty since (presumably) the testing methods are not consistent for all manufactures. One GLARING example of inconsistency is the Spyderco uf media which is reported as 7 micron on this chart. It tends to polish as good or better than the DMT EEF (3 micron).

There is a whole other discussion regarding testing of edge holding relative to the media used to produce the edge. There are some surprising reports out there, and since my findings are pretty subjective at this point, I will keep them to myself. There are some people out there that spend a LOT of time working with this stuff.

"There are some people out there that spend a LOT of time working with this stuff." That's true and I don't know if I want to be one of them or just get the results of their labor and be done with it. I do like to experiment though. You made some good points and I guess there isn't a perfect comparison between manufacturers. We'll just have to get as close as we can.

Jack

[ricklee4570]

This is a very informative thread! Thanks to all who have participated!

[Kev-Man]

Speaking of grits. There seems to be a vast difference in the numbers used depending on the type of stones.

You mean there are other ways of sharpening besides free hand on Japanese Water Stones? J/K

[jackknifeh]

You mean there are other ways of sharpening besides free hand on Japanese Water Stones? J/K

Of course not! What was I thinking???

Jack

[dshreter]

Sorry for my departure, but to clarify my original post, in describing the spyderco factory edge, and asking about polished edges, I'm referring to both the edge and the bevel because (at least according to my understanding) they are the same from the factory, without any microbevel being applied.

Perhaps my surprise at the apparent sharpness of the factory edge relates to what one contributor has mentioned in the thread that the blades are buffed, but not long enough for all of the deep scratches to be removed. The result is a fine edge and bevel, but deeper scratches remain present that minimally impact the sharpness and performance of the blade.

I'll have to try whittling hairs with my caly jr.... that's a neat trick.