Polished vs. unpolished edges

[Evil D]

It's my understanding that a polished edge is the sharper of the two...but is it just me or does a polished edge always feel more dull than an unpolished edge? I've noticed that when i really get the leading edge polished out good, it just feels dull compared to before i polish it out. There isn't really a difference in feel when slicing phone book paper or TP, but there's a noticeable difference when shaving hair..the polished edge always pops them off easier. Of course, before i polish the edge it still shaves with ease.

[Frapiscide]

If you do the thumb tip technique for checking sharpness, yes, it'll feel duller because it lack the teeth for the slicing of an unpolished edge.

[Evil D]

If you do the thumb tip technique for checking sharpness, yes, it'll feel duller because it lack the teeth for the slicing of an unpolished edge.

That's what i was thinking. I've also tried Murray Carter's three finger test and to me that just makes no sense at all despite his obvious knowledge of sharpening...to me a toothy edge just feels sharper using his method than an obviously sharper edge.

[Rhiney]

Interesting. I know for me a polished edge lasts better. Curious what some of the more experienced sharpeners on the forum have to say...

[Evil D]

The more you can refine that leading edge, the finer you can make it, the less jagged metal there is to chip off when you make a cut, so yeah a polished edge will stay sharp longer.

[chuck_roxas45]

I dunno about sharper but I still like polished bevels. Edge finish is another thing though. I'm finding that I like a bit of a toothy edge nowadays. The sharpmaker fine rod, at about 1200 grit(net info, :D ), I find gives a good edge for a carry knife. A hair whittling edge finished at 1 micron would be no slouch for daily chores. I've also found that a 600 grit edge finish(still hair whittling) is a very aggressive cutter that will simply zip through cardboard and even through tough and fibrous material.

[Evil D]

Yeah for the record i'm only going up to 1000 grit so that may still be toothy for you micron guys. I don't polish out the whole bevel either, you could probably call what i do a micro bevel, i just raise the degree enough to hit the leading edge and polish that...maybe 1/3 of the total side of the bevel gets polished.

[.357 mag]

When I first got my edge pro, I polished all my edges. Since I switched to the Congress stones, I've stopped at 600 grit and just strop the burr off. I like it better.

[chuck_roxas45]

I think the degree of polish you finish your edges with will also depend on what materials you normally cut. Some materials will call for special application edges, so to speak. After hanging out for a few weeks at a friend's auto repair shop, cutting a lot of very dirty, heavy gauge cardboard(the kind that some large parts come in), I do find that my grey para, finished at 600 grit will allow me to cut with less force applied at the handle(slicing cuts), even after almost 2 weeks with no sharpening or even touch ups.

I've also experienced that a 1 micron edge will be less efficient than a 600 grit edge, at slicing cuts on cardboard.

[Evil D]

Chuck what you're seeing is a sort of micro serration effect. On some materials, particularly hard things like heavy gauge corrugated, a polished edge will slide before it cuts, whereas a toothy edge will saw through.

[chuck_roxas45]

Chuck what you're seeing is a sort of micro serration effect. On some materials, particularly hard things like heavy gauge corrugated, a polished edge will slide before it cuts, whereas a toothy edge will saw through.

Yup, I'd say so. :)

[jackknifeh]

The time I see a difference in a toothy vs polished edge is when cutting something like a tomato. A toothy edge will saw through the skin on the first cutting motion where a smooth polished edge will slide along the skin. After the skin is initially cut the edge doesn't seem to matter. I've used a polished edge on tomatos and found I mash into the tomato a little before a smooth edge finally cuts through. But the toothy edge cuts through the skin immediately. I have also popped hairs off my arm after using a 220 water stone that comes with an Edge Pro.

When cutting or whittling wood I like the polished edge. The toothy edge seems to get dull quicker because the tiny teeth may break off easier or that's how I picture it anyway.

Jack

Jack

[unit]

The answer to the questions is dependent on the use of the knife.

Push cut vs slice?
perpendicular vs accute cut angle?
soft vs hard vs heterogeneous substrate?

Depending on what I am doing, I will select different edge finishes.

People often use a tomato as an example of reason for a toothy edge. This substrate is heterogeneous (tough hard skin over a soft core). Further if you cut the tomato down the middle you have the cutting plane nearly perpendicular to the substrate (if you cut a thin slice off an end of it you have a more acute angle). Then you can explore the differences between push cutting and slicing

I find that (at least with the steels I use) a polished edge works well for me. I am a push cut kind of guy :)

I have demonstrated with videos how polished edges excel for push cutting rope and Kevlar if anyone has not already seen them. These also demonstrate edge holding abilities (at least for the uses shown).
http://www.youtube.com/watch?v=u4rDIFFyXVk
http://www.youtube.com/watch?v=4l2fItEF ... re=related
http://www.youtube.com/watch?v=tTTpFqO- ... re=related

[Zatx]

I agree.

Polished edges (what I have) are better for push cutting. A more toothy edge is best for sawing motions like cutting up cardboard.

Where the polished edge really shines is cutting open blister type packs. You know the kind... the thick heat formed packaging. Take a knife with a polished edge to that stuff and you'll do like me and stare at your knife in amazement. There is very little friction and it takes next to no pressure to slice it up.

[chuck_roxas45]

I agree.

Polished edges (what I have) are better for push cutting. A more toothy edge is best for sawing motions like cutting up cardboard.

Where the polished edge really shines is cutting open blister type packs. You know the kind... the thick heat formed packaging. Take a knife with a polished edge to that stuff and you'll do like me and stare at your knife in amazement. There is very little friction and it takes next to no pressure to slice it up.

Hehehe, yeh. I cut blister packs by putting them on the table and insert the tip and just slowly push on the spine with my left thumb. Very controlled. No tubes of superglue perforated at the side. :p