Thread: DOUBLE CHEESE BURGER FOR THOUGHT - OMG Edge Trailing!

Tim’s recent post. (How effective is clean fabric?) and the clear micrographs posted, show the effects of stropping and pressure on the edge and brought up some thoughts on honing.

Its all about the pressure.

The micrographs show how edge trailing (stropping) puts most of the pressure on the trailing edge. Notice how half the fine stria at the edge has been removed in 40 lite laps on plain linen.

So, what happens on a stone?

When honing,(edge leading) the same thing happens, more pressure is put on the back of the bevel, not the leading edge. Yes, you can torque the razor and even out pressure to the leading side, (edge) of the blade. But on hollow ground razors it is probably easier than most think to flex the blade and lift the edge off the stone, compounding the issue, we are talking microns here.

Now, I am referring to finishing stones, as aggressive low grit stones grind the bevel flat mostly, and are used with more pressure, Finish stones are not as aggressive. A lot is technique driven.

This is easily tested, with sharpie ink, an often-overlooked definitive test. You are removing ink at the edge, or not. Colored ink is much easier to see with the naked eye, I use red, blue and green. Red is the easiest to see, I will often change colors, so as not to have to remove ink from a blade. WD40 on a paper towel will easily remove sharpie ink.

Having delved deep into finishing with Jnats, I turned to honing videos by long time Japanese finishers, of which there are many good old videos, Looking at traditional Jnat razor honing, many of these videos are not in English, but does not matter for viewing technique. Edge trailing is a common finishing technique, just a couple finish laps. I have adopted this for final finishing strokes on all stones in addition to stropping between stones as part of my honing routine to ensure the best finish on the edge at each stone. It’s all about the edge.

When used as a finish stroke in a progression, raising a burr is less of an issue, stropping between stones, lessens the burr potential even further. In progression, the next stone, edge leading will cut off any remaining burr.

It can be an issue for final finish strokes, if too much pressure or too many strokes are used, yes stropping can remove them, but it breaks off the burr as opposed to a clean cut from a stone. So, the trick is just a couple lite final finish strokes and not make a bur

If you are having edge issues honing, this is just something to try, and it may make you pay a little more attention to what is happening to the edge.

And it all can easily be reversed, by lightly jointing the edge with one stroke and 15-20 laps on the finish stone will bring the edge right back.

Your thoughts?


1st off the hone.


2nd off flax linen, look at the edge.

Dunno, I do a couple of edge trailing strokes on the hone followed by a couple of light edge

leading strokes when I am done on a hone.

Bob

I might be making assumptions here but we tend to use ink for mainly bevel setting or at least i do. Once i know i'm up to the edge then i lay down that sharpie and forget about it.
Skip forward to finishing on an Escher. Very light strokes with less pressure. For the record i don't use noticeable pressure anywhere in the progression but on an Escher i'd make an effort to use less pressure. Reason being is that i've seen what an Escher does under a scope and it's not pretty.
Those light strokes and even maybe the slight wearing down of the spine tape could or should mean that i'm not reaching the very edge at least in places. (or maybe not reaching certain parts as effectively as the rest of the bevel) This can show up as odd parts of the very edge reflecting light. Even though those reflecting parts pass HHT and shave well, probably because i arrived at the Escher in a good way and stropped well after the finising stone.

The reason for all this not reaching the edge totally on a finishing stone is because of what Marty said about more pressure being distributed to the rear of the bevel. This is something i have know for years.

Whilst writing this i can't help but think that maybe if there actually is a problem at all? We should finish with circles instead of X's because the uneven motion of a circle rocks and tilts the bevel making sure all parts hit the stone..
I have heard somewhere over the years that finishing with circles is a big, "No". Never tried it or even contemplated it until now.

I have just woken up so that excuses any craziness i may have just spoken

Circles, wavy, snake like up and down strokes and even up and down 90degree finish stroke appear to have been common with old school Japanese razor honers, just a few lite laps.

They all probably work for the same reason you mention.

It is technique driven, but for guys new to honing, more pressure can compound the ability to hone the edge and is something to think about.

Testing with ink is a quick, simple non-destructive test. Even looking at an edge with some magnification, that touches the edge can be edge damaging, not that much but some.

Just something to think about, when trying to improve an edge. A couple edge trailing finish laps is an easy thing to do.

You can use moderate finishing pressure then use very light finishing pressure. If you look, you can see a difference in how the stone hits the bevel, lighter pressure will build a finer pattern closer to the apex.

After honing, but before stropping, you can do a few light laps, say 4-6, on a smooth dry stone and that will boost the HHT a little. Alex Gilmore clued me on this. Later on, I was chatting with Takeshi at AFramesTokyo about this HHT boost and he immediately mentioned removing a finishing burr, so the idea did not seem unknown to him. I’m using a small piece of uchigumori, but most smooth jnats seem to accomplish the same boost.

Most definitely pressure is the biggest game changer. At the scale relevant to a razor's edge, pressure is extremely important, exponentially more so at the finish. Any trick you can use to reduce pressure beyond what is sensibly possible is a plus, when you are chasing that ultimate edge. Pressure regulation is more important than bumping up to the next finer honing medium. When I began holding my pasted balsa strops vertically instead of horizontally to take the razor's weight out of the equation, the difference was an epiphany.