Fickle Hair test
I was having a similar conversation with a new honer recently about the varieties, fickleness of “Hair Test” and how to interpret.
I use hair test but not HHT, “Tree Top”, grab a hair after bevel set and between stones. I rest the spine on the skin and lift the edge about a ¼ inch and just see if it will grab a hair at the toe, middle and heel. I then look at the edge from the side, (for chips) and straight down for any shiny spots indicating the bevels are not fully meeting.
It is not uncommon that the edge will not grab or cut hair, but the bevels are meeting, and edge well formed, especially at higher grits.
The problem is that the edge fin is bent away from the edge. Which way it is bent depends on the direction of the last lap. So, if you flip the razor and retest often the edge will catch and cut, the fin is now bend down towards the skin. It does not take much bend for the edge not to cut. This can also occur with the blade parallel to the skin.
With the razor resting on skin and angled up, the little bit of fin deflection is exaggerated. Flipping the razor puts the actual edge almost level.
I typically strop on firehose or sailcloth strop between stones, (about 10 laps) to remove any loose fin and straighten, but often linen will not fully straighten the fin. It will remove loose flashing and polish the edge though.
Stropping on leather, as few as 10 laps will straighten the edge.
So, if the edge does not grab a hair or cut, first look at it from the side and straight down. If there are no major issues, try flipping the razor. Then strop on linen to remove loose flashing then strop on leather, to straighten, then back on linen to polish the straighten edge. Now do your hair test.
This is even more critical at the higher grits as the fin, (the actual cutting edge) gets thinner and longer.
Jointing is another option, cutting off the fin cleanly making a straight edge and building a new shorter fin. Try it, next time the edge does not cut hair, flip it, and try again, you might be surprised.
I was having a similar conversation with a new honer recently about the varieties, fickleness of “Hair Test” and how to interpret.
I use hair test but not HHT, “Tree Top”, grab a hair after bevel set and between stones. I rest the spine on the skin and lift the edge about a ¼ inch and just see if it will grab a hair at the toe, middle and heel. I then look at the edge from the side, (for chips) and straight down for any shiny spots indicating the bevels are not fully meeting.
It is not uncommon that the edge will not grab or cut hair, but the bevels are meeting, and edge well formed, especially at higher grits.
The problem is that the edge fin is bent away from the edge. Which way it is bent depends on the direction of the last lap. So, if you flip the razor and retest often the edge will catch and cut, the fin is now bend down towards the skin. It does not take much bend for the edge not to cut. This can also occur with the blade parallel to the skin.
With the razor resting on skin and angled up, the little bit of fin deflection is exaggerated. Flipping the razor puts the actual edge almost level.
I typically strop on firehose or sailcloth strop between stones, (about 10 laps) to remove any loose fin and straighten, but often linen will not fully straighten the fin. It will remove loose flashing and polish the edge though.
Stropping on leather, as few as 10 laps will straighten the edge.
So, if the edge does not grab a hair or cut, first look at it from the side and straight down. If there are no major issues, try flipping the razor. Then strop on linen to remove loose flashing then strop on leather, to straighten, then back on linen to polish the straighten edge. Now do your hair test.
This is even more critical at the higher grits as the fin, (the actual cutting edge) gets thinner and longer.
Jointing is another option, cutting off the fin cleanly making a straight edge and building a new shorter fin. Try it, next time the edge does not cut hair, flip it, and try again, you might be surprised.
