Efficacy of sub 3 micron abrasives

[theonew]

I finish all of my knives on Ultra-Fine Spyderco ceramic which to the best of knowledge is a 3 micron sized abrasive. Using it I have been able to get all of my knives to whittle hair easily. I have very fine light blond hair and with certain steels, most notably the 52100 in my Spyderco mule, I've even been able to whittle a single section of hair into 3 "slices". Awhile ago I bought some .5 micron abrasive sheets from Lee Valley. I've tried using them several times but do not notice any benefit whatsoever. Has anyone here found a noticeable performance enhancement using sub 3 micron abrasives?

 

[Knife_Geek]

I too can get a hair whittling sharp edge off of the Spyderco UFs. When I go down to the super fine abrasives (0.5 0.25) I notice a definite increase in its ability to push cut. I can easily push cut an entire sheet of newsprint with no tearing or snagging.

 

[flashlife]

Sub-micron abrasives polish the blade/edge. Most actual sharpening (ie, removing metal to form or dress the edge) must be done with larger grits. Sub-microns won't sharpen a damaged edge, (without a LOT of work) but will remove scratches, leaving a mirror-like finish. They remove the 'tooth' from the edge.

There is some evidence (mostly anecdotal) that a polished edge stays sharp longer than a toothy edge, since a polished edge has no 'jaggys' to catch on a hard surface and cause chipping, bending, rolling, etc. Also, a polsihed edge is less likely to corrode, rust, etc, since the smoother surface has fewer scratches, nicks, nooks-crannies, etc to hold/trap contaminants which makes corrosion more likely to start.

The disadvantage of a polished edge is that, without the 'tooth', the edge may actually slide on a slick surface, like rope, fabric fibers, etc, rather than catch and begin to cut. Traditionally speaking, 'slicers' need a toothier edge so that the microscopic 'teeth' can catch and start to cut the tomato skin, etc.

I've found that if your knife is a light-duty type, and you don't cut hard objects, you can keep the edge EDC sharp by stropping frequently using sub-micron abrasives. The Lee Valley .5u sheets would be good for this.

 

[Knife_Geek]

while I have heard that about cloth/rope cutting I personally have never had trouble cutting rope or cloth with a high polish edge. I might just not cut enough of it to notice but for me the sharper the better it cuts just about everything.

 

[Jason B.]

The spyderco UF is a great finishing stone and produces a nice edge. Going a little further does make a difference though, I like the finish of 1 micron diamond paste the most because it leaves a nice polish and a little bit of tooth. The steel that you are sharpening will also determin how fine the edge will get, some steels don't respond well to 0.5 and 0.25 micron abrasive. Your mule can get much sharper, mine shaves better/cleaner than my schick with 3 blades.

Not all the pic's are that clear, its hard to take a pic of a polished edge without the right lighting. A little step by step that I did on a S90V millie.

Spyderco UF ceramic

1 micron diamond paste

0.5 micron diamond paste

and a little backed out view

 

[theonew]

Amazing pictures knifenut1013 :thumbup:

Perhaps I just haven't been patient enough with the .5 micron sheets. Guess I'll try it again

 

[Jeff Clark]

There are other variables to consider besides the size of the grit. For example there is the type of grit and the substrate you are using and in addition the type of steel that you are honing. I have not found Pinnacle honing film to improve my edges beyond what I get from UF Spyderco rods. On the other hand when I strop my edges on photo paper coated with .5 micron diamond paste I can get an edge to cut toilet paper. I see diamond paste in the micron and submicron range to help almost any kind of edge. This is particularly true on stainless steels with coarse grain structure. The diamond grit seems to shape large carbide bits down to a finer edge.