Why kill an edge

[AcesandEights]

A quick back story.

I purchased a custom razor from SRP member Frans awhile back. Upon receiving, the initial and subsequent shaves were beautiful...like NO other razor I have in my stable, be it new, used, rehoned by myself or by others. It was amazing. Fast forward a lot of shaves (I shave daily), I felt it needed to be touched up. I contaced Frans to ask him his honeing/stropping, because it was such a fantastic shaver. He, in fact, shot a quick video of him honing. So, out came the 4/8K and 12K. I went to touching it up as I normally do (taped, like Frans did), then onto the strop. However, it just wasn't up to snuff, even compared to any of my other razors I have honed. Fast forward, I contacted Glen (GSSIXGUN), who suggested I kill the edge, hone, repeat maybe 3 times. He said he has run into brand new custom razors, upon rehoning require the edge to be killed a few times. OK, that's what I did...Killed the edge on glass, then to 4K, 8K, 12K, then stropped....then repeated the same 2 more times. Test shave and viola...What the heck?!?! It WORKED! It shaved beautifully! Not that I doubted you, Glen. But, it just don't make sense to me. How can a razor that shows ALL outward signs, from ink, to hair popping, to feel on the hones, etc., etc., etc., yet shave badly. Yet, after 3 kills and hones, it shaves as smooth as greased glass?

Here's another example. I received another model of one of Frans custom razors, not too long after the 1st one. This, too, shaved wonderfully right out of the gate. When time for it to be touched up, I thought, "I'll try my way 1st. 1 and done." NOPE, it pulled like a freight train. So, yesterday, I went to Glen's 3 Kill method. 3 kills and hones, then to the strop. This morning I used it and that one, too, worked as the other. It was heavenly!

[JimmyHAD]

There was a guy on SRP years ago named Bart, from Belgium. A coticule connoisseur, and said to be quite a honer.

He was the first person I ever heard to suggest dulling the edge on a water glass. In that case it was so the honer was starting from zero and wasn't getting 'false positives' in his sharpness tests as he progressed in the honing.

Not to contradict Glen, he has undoubtedly honed way more razors than I have, but, having tried it once after Bart posted the suggestion, I've never 'killed' an edge since and so far so good. Interesting that it worked so well for you.

If I ever run into that situation maybe I'll give it another try.

[gssixgun]

Bart was by no means the first...

In fact there are many old barber's hones / stones that show the corner cut marks from them "Killing the Edge"
It is also a tool sharpening trick, we all act like we invented the wheel, it simply isn't true we adapt ages old concepts to our use, sometimes things that were used by ages old SR users..

Killing the edge on many of these new customs works because the original edge was over worked to begin with so you want to get past that steel

[DoughBoy68]

Never did understand the concept as to why/how it works but over the years have run into a few that just wouldn't 'pop' to coin a phrase for Glen. You can hone and hone on one with no results then kill the edge a time or two and 'Bingo' shaves like a dream.....go figure!

[criswilson10]

I heard a theory from an old tool maker that applies to new plane irons and I think new razors as well: During heat treatment the edge gets hotter than the body which leads to a harder edge after the quench. Essentially about 1/32 of an inch at the edge is over hardened. If honed immediately then you will get a smooth edge, but the next honing will relieve the stress in the edge and the blade will be chippy. You then have to keep honing until the over hardened (chippy) edge is removed. Killing the edge just speeds up the process and three to five kill/hone cycles will get you to the properly hardened metal.

That was his theory and I just follow his advice: If a new blade gets chippy, kill it and hone back the edge a hair.

[Phrank]

Interesting- as when I started to learn, I'd get to 8k, after shaving arm hairs at 1 and 4, and most every time the edge would die and I'd kill it and start over - presto, seemed to get a great edge.

Finally after doing things twice, I killed the edge before I started, and smooth sailing since. I read somewhere that aside from getting new steel, it also has some "joining" effect...I have no idea, still a novice, but works for me....:-)

[JHBBlade]

Interesting!

I'm in the middle of muddling my way through a Tuckmar that was NOS, and just does not want to form a nice edge to the bevel.

I can get it to shave okay, but never at the level of my other razors. Fresh off the hone it feels more like a razor with a week and a half under its belt.

Having spent a lot of time looking at the edge in between honing I've come to the conclusion that the edge might be over hardened due to evidence of likely chipping on the very edge of the bevel. Also in some areas the material near the edge looks like it had suffered corrosion at a micro-level. So I'm now taking off material from the bevel until I can get to shave off the 1k. The more material I take off using the 1k, the better the edge of the bevel starts to look,confirming my gut feel that was telling me I need to find fresh steel.......... If I eventually succeed then I'll be in 100% agreement with the 3 killed edge technique!

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[Euclid440]

I see this often on customs, that may be harder that production razors. It may be the heat treat, over heating the edge, work hardening or aggressive use of belts.

I also see this, when doing edge restoration, where a bit of the edge has been removed as in large chip removal. And with new honers. where low grit stones, Diamonds or lots of pressure and/or laps, will “overwork” an edge or cut deep into the steel.

Diamond plates are notorious for cutting deep and weakening the steel below, (even after the stria has been removed) and, I suspect some of the newer aggressive Ceramic belts can do the same. The razor may shave well, but maintenance stropping flexes the weakened edge and it eventually breaks off, causing a micro-chipped edge.

When I encounter this, I remove the micro-chipped edge and re-set it. Once the bevels are flat and in the proper angle, it is quick and easy, to bring the bevels back to meeting. As said sometimes the edge will have to be remove 2-3 times, the amount of material removed is still, microscopic.

How you remove the edge does not matter much. Running it on glass or other hard surface, rolls the fin and honing cuts it off, jointing on the corner of a stone, cuts the edge off cleanly, or you can also just hone it and eventually the edge will be removed, or add a layer of tape and create a micro bevel or new higher angle edge.

I like jointing on the corner of a stone, as I believe it is cleaner, quicker and leaves a straight edge that just needs to be brought back to meeting, a matter of just a few laps,10-15.

I often kill/joint an edge before going to the finish stone and reset on the finish stone, for a stronger edge.

If making a micro-bevel, try adding a layer of clear packing tape, it is thinner than electrical tape and stronger than scotch tape, that also works. Packing tape, (the clear one, not reinforced) is slick and very strong.

Exactly why this edge chipping occurs, I don’t think anyone knows for sure, Removing the edge and re-setting it is the cure.

[petercp4e]

My guess is that it both gets rid of a chippy edge and gets to better steel.
The times that I have killed an edge come from seeing chippiness on the edge when I have finished my regular honing routine to 16k.
I use an aprox. 500x scope to look at my edges. Once in a while the edge still looks chippy no matter what I do or how long I do it. Killing the edge and going back a step or two on the stones, then working back to finish has pretty much always worked for me in bringing back the total smoothness. Only on the rare occasion where there is deep pitting and really bad steel does it not work.

Pete <:-}

[JHBBlade]

This thread is very helpful. Thanks Gents.

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