Under cutting Water - Coticule

[driftwood]

Ok so I have a question about honing, but first some quick background.

I have taken to the foloowing honing progression: 800K King for bevel setting, 4K Norton, Very fast (but very small 1.5"X4") coticule with heavy slurry using a Dilicot and circles method down to water, finish on a different coticule using water then Smith's Honing Solution. 4 laps Crox then felt/leather. Usually get HHT results in the 3-4 range across the length of the blade.

During my dilicot on the first coticule I use circles combined with half strokes and X-strokes, I undercut the slurry during the whole phase. But once I get to water only the edge stops under cutting the plain water. So is this impacting the final result of my honing? Is it necessary to have undercutting at all? What is this telling me about the edge? Is it not keen enough and should I have spent more time on the watery slurry?


Out of curiousity what are peoples thoughts on undercutting in general, is it something you pay attention to?

 

[Gamma]

I found that testing and comparing the edge before/after having/not having undercut is what matters.
Not everyones technique, pressure, stone, blade, etc will yield the same results here.
For me - undercutting water or slurry is a relative thing and there are many degrees of undercutting.
Slurry will undercut more easily than water due to surface tension.
I rarely do water-only laps any more so there's that.

 

[blackhhawk]

I find that if I don't get an undercut on water there are a few options. Sometimes I'll just keep going with it and the undercut comes back. Sometimes I take a step back and raise a little slurry to work on the edge more. Sometimes it just takes some circles/pressure/half strokes. Pressure meaning just a tad more than what you were using. No need to bear down on the blade.

Ive vey never done any kind of comparison or testing to see if the undercut on the water stage effects anything, but I see it as an indicator of the edge making contact in that spot or the edge needing more work in that spot. Play around with it.

 

[Sando]

I use undercutting as a benchmark towards success. I definitely pay attention to it.
It's time dilute my slurry when I see it working good.
I think it's necessary to see it as I believe it's a signal that the bevel has come together completely.

 

[blackhhawk]

I use undercutting as a benchmark towards success. I definitely pay attention to it.
It's time dilute my slurry when I see it working good.
I think it's necessary to see it as I believe it's a signal that the bevel has come together completely.

It depends a lot on how much water you have on the stone too. I've seen undercut when the bevel wasn't ready to go, so if you pay attention to the undercut you can start to understand it enough to where it can help you analyze where your edge is in the process. I wouldn't say that it's a black and white indicator, but if you pay attention to it enough, it can be used as a tool like other types of feedback indicators.

 

[jpcwon]

I use undercut primarily to tell me that the entire edge is making good contact with the hone. Like Blackhawk said, it's not a 'black & white' indicator of keenness though, as there can occasionally be good undercut despite the edge not being quite 'there'(too much water on the hone, etc...) I usually try and "memorize" what the changes in the undercut start to look like & feel like as the edge starts to become keen, so I can use that as a feedback indicator down the road...

 

[Fuzzy Chops]

... 4K Norton, Very fast (but very small 1.5"X4") coticule with heavy slurry using a Dilicot and circles method down to wate,...

I don't think you should need more than a milky slurry after the 4k Norton. My guess is that you have a slightly convex bevel from the slurry and that prevents the undercut as you dilute (too quickly) to water.

 

[Disburden]

I don't think you should need more than a milky slurry after the 4k Norton. My guess is that you have a slightly convex bevel from the slurry and that prevents the undercut as you dilute (too quickly) to water.

I agree here.
All you neee is a skim milk like slurry after a 4k. A heavy slurry will cause you to start over on most coticules.

 

[Gamma]

yup

I don't think you should need more than a milky slurry after the 4k Norton. My guess is that you have a slightly convex bevel from the slurry and that prevents the undercut as you dilute (too quickly) to water.

I agree here.
All you neee is a skim milk like slurry after a 4k. A heavy slurry will cause you to start over on most coticules.

 

[PithorK]

After establishing the bevel, which I test by means of the thumb pad test and shaving arm hair at skin level, undercutting slurry is the main aspect I pay attention to to monitor progress. Although as said, there's different ways of undercutting, especially with water.

If you use a lot of water, it will be easier to undercut it. Also if you use soap in your water it will always undercut since the soap breaks the surface tension of the water. Also the degree of hollowness has something to do with it, or at least that's how it seems to me.

And yes, you don't need more than a milky slurry. In fact, the thicker your slurry, the lower the level of final sharpness is that you can get off that slurry. That is basically the reason for diluting: to decrease the level of slurry dulling. Very thick slurry will do nothing more than unnecessarily eat away lots of steel.

 

[driftwood]

Thanks guys!

Since a lot of my recent honing has been on restores I was going to a heavier slurry after 4K to ensure my bevel was set. I use a much more dilute slurry on razors that are not coming off the work bench.

The surface tension thing makes sense as I get my under cut back when I move to water/honing solution.

I'm at the stage now where I'm noticing things like undercutting and things as my pressure and honing stroke is now mostly auto pilot. Ill keep working with the two stones and various razors and figure it out, I'm sure.

Thanks again guys

 

[Neurotopia]

One thing I notice is that my Chosera 1k, when a bevel is really set well, the undercutting is almost unreal. Like I'm honing on a liquid that doesn't have hydrogen bonds or something, it just all shoots right up the edge uniformly along the length of the blade.

 

[driftwood]

Ok so I grabbed a new razor last night, a 7/8 Worsty that had be honed with tape previously. I reset the bevel without tape in my 6x2 la grise on a thinner slurry than I have been using (someone suggested that). I then used mostly circles and half strokes (after watching a Utube video by Maximus(?)). I took it through the dilutions then did an HHT, I got solid 3 and almost 4 on the toe and heel, but sweet nothing through the middle. I went back to water for some more circles, half strokes and X strokes, nothing changed. It was getting late so for giggles I did some finishing on the same stone using lather, still no improvement on the edge via the HHT. I then used a bit of CroX (10 laps) and I hit a minimum of HHT 3 across the length of the blade. Did 60/90 felt then leather and its waiting for it test shave this evening. I'm beginning to think the 6x2 Coti is a little bit finer than my smaller one so my plan is to focus on it, get consistently good edges then take one of those edges to the small Coti and see if there is a change and whether its an improvement or not.

Thanks again for all your input guys, very much appreciated and keep it coming.

Cheers