Resistant chipping

Greetings,

A fairly new shaver sent a couple blades for honing. He mentioned a few micro-chips in the edges, but not really much about the shaves from them. One is a custom damascus blade from a well known maker.

I looked at the damascus & ran it around on a med speed coti w/ very light slurry to see how it affected the chips. It either had little affect or old chips were replaced w/ new ones. 'So I tried a thuringian - same result. Asagi - pretty much the same. 'Wondering if there's anything specific to damascus blades that either make them prone to chips, or if there's a way to address them I've not thought of yet.

'Do appreciate your help.

My Very Good Friend,

I'm of no help but as you well know I have a thirst for knowledge especially about honing. While SRP's System should keep me informed via email about the responses to your thread, please keep me up to date if I miss something. :bow: :tu

Count on it, my friend.

Makes me wonder ...... since it is from a well known maker I assume the spine is plenty thick enough for the width of the blade to give proper geometry for honing ..... what is it 17 degrees or somewhere in that neighborhood ? Is it a wide bevel without a lot of meat ? Assume it is a wedge, 1/2 hollow, being a custom ? I'd probably put the coticule back in the drawer and maybe get the trusty old 1k chosera out and do light circles until the chips are gone and progress from there ...... but not being on the spot, or seeing the razor firsthand, I really don't know for sure. Someone will be along who knows for sure. :)

Just searched my Pics Library, I have some shots of a Damascus (Pattern Welded) that had come in for honing that had intermittent chipping issues, what I mean was one of the layers of steel was fine and the other was chippy.. You could see the difference under magnification..If I can find them I will post them..

I finally solved the issue with a complete bevel re-set then went Shapton 1-2-4-6-8 then added a second layer of tape and did a micro bevel on the 16-30 that did the trick on that razor..

Something to ponder on Rob, is if the chips are only in one layer or are they showing in both types of steel...

A temper/heat-treatment issue ?
Not from my razor honing skill set (very limited) but from my exposure to tool steels, high pressure pipe/welding.

Jimmy & Glen, Thank You both so much.

I was hesitant to go to the lower grit stones, 'cause it was really sharp to begin with.

I couldn't help but wonder if the spacing of the chips corresponded to the change in layers as it came into the bevel.

Jimmy, it looks 1/4 hollow - a bit more hollow than say, a Williams 1/4 grind. I Started with one layer of tape, and added a layer to see if it helped. I seem to talk myself out of what I should know better - which is when it fights me, go to bevel. I still remember thinking Glen was being immodest when answering the question - how do you know if a bevel needs a reset. He said - if I didn't set it. Its been a while since I concluded that was *not* immodest.

Gents, I'll post again after a reset. Again, Thank You both for your kind help.

Chosera, then Norton 4k. Clean Steel - whatta concept. As usual, gents - you nailed it again. No chips, thin, even bevel - occupies about 1/3 the area of the former bevel. 'Should be sweet, when done.

Thank You again!

Final result after Norton 8k > Gokumyo 20k > Few strokes on Asagi - lopped hair w/ authority 1.25"+ from point of hold. The tiniest of chips reappeared at 8k, but polished out. 'Makes me wonder if a few shaves will see them again. Either way, this one'll shave.

Would this be the Ockham's razor answer for a Razor honing question?

I honed a very hard razor today, displaying the same problem. When I come across this I do not go to the 1K but the 4K, Norton in my case, to re-set the bevel after lightly jointing on the corner of the stone. I do this 2-3 times, it does not take that long or remove that much metal, the bevel is already flat. You will get a straight edge stress free edge.

The goal is to get to good steel, you could just re hone, but jointing get the edge straight and the 4k re-sets the edge with a finer stria.

I suspect many of these problems come from aggressive honing on low grit stones or diamond plates on hard steel or makers grinding belts.

In this case it may be the steel and the bands of wootz steel, but it may be from the hardness of the steel.

This and an extra layer of tape, has work well for me on hard chippy blades.

I had two Damascus Razors from the same maker and they microchipped very easily. Maybe 10 shaves or so and they would start to appear and during honing once away from the lower grits they would appear while honing at the medium higher grits. I found by doing kamisori style honing the chips wouldn't appear while honing.

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Originally Posted by Euclid440

In this case it may be the steel and the bands of wootz steel, but it may be from the hardness of the steel.

This and an extra layer of tape, has work well for me on hard chippy blades.

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I don't want to sound picky here but I doubt the Damascus steel used contains any wootz steel. I know this site prides itself on giving accurate credible information and someone reading that might think that if they are buying a Damascus steel razor they are buying a razor made of wootz steel, which is unlikely to be the case :)

Neither are they likely to be Damascus steel, but we all know that modern pattern welded steel is commonly and incorrectly referred to as Wootz and or Damascus steel.

Pictures would help a great deal. Perhaps the next time the blade produces chips would be a good time since they sound as if they have been honed out.

That the chips would only occur in one layer versus the other would be a real treat to see. I have several questions that I would pose if that were the case. The steels used, any forging done and particularly questions about the blade's heat history are a few that come to mind. Knowing the setup of the blade prior to grinding may also be helpful as there could be some remaining decarburization. I think this is a more remote possibility because of the hollow grind, but it has to be accounted for.

Since this is a "well known" blade, it could be one of mine. I'm always interested in feedback in any case, as I would recommend for anyone making blades whether they are patterned or not. If it's not, I'm interested in the questions I have and would still encourage confidence in pattern welded steels regardless.

I had a discussion with a tool, knife and razor maker some time ago about the use of 'pattern welded' steels, especially with regards to the cutting edge.

He maintained that the best designs have a small layer of non-pattern welded steel along the cutting edge, maybe 1/4" or less in width. That was supposed to give a good homogeneous steel to hone.

He also said that all the newer pattern welded steel knives and razors he had used where the pattern runs into the bevel are 'toothy' because of the properties of the different steel make-ups.

I am not a steel master so I don't know if that is correct, but I do know that I have seen plenty of old 'damascene' blades (pattern welded) with this thin billet of steel. There must have been a reason they made the razor (a few were kamisori) in this fashion.

Regards,
Neil

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Originally Posted by Neil Miller

I had a discussion with a tool, knife and razor maker some time ago about the use of 'pattern welded' steels, especially with regards to the cutting edge....

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It is a useful discussion. There are specific conditions that could produce one layer that chips more than another. There are historical precedents for the development and use of patterned steels and for using a mono steel at the edge.

I can't speak for any one individual maker's choices of steels except my own. I'd like to believe that we have all had the same basic education about steels and mixtures in pattern development. I use 1095 and 15N20 (essentially 1075 with 2% nickel). The nickel resists etching and is what creates the contrast between layer "colors." Given carbon migration during welding the billet will end up being at or near 0.85% carbon and that is considered the eutectic sweet spot for carbon steels, neither too little carbon nor too much. When this steel is honed there will be a clean surface at the edge that does not show a pattern and since the carbon has averaged between both kinds of steel and there are not any other significant alloying differences, it should function as a mono steel that has a pattern only where etched. I do not expect one layer or the other to function, or risk not functioning, differently from the other. During heat treatment, both layers achieve the same hardness so there is no myth of hard or soft layers in PW steel. That would require thermal controls that only a very few makers I know are capable of and it's not of any practical value in an edge regardless. It is this reason I choose the steel types I do.

Other alloys with other content differences may perform differently and this is where the maker has their say and the obligation to explain those differences when they become apparent. Some pattern welded steel makers choose to use pure nickel shim stock in the layers. Not only will that nickel layer not harden (it won't chip but will deform), but that layer also functions as a barrier to carbon migration and the carbon averaging that I expect, cannot occur to the same degree.

Using a strip of steel along the edge can be a practical blacksmith practice. It allows the smith to save money by using a smaller amount of high quality edge steel and lesser quality PW steels for the spine, or it prevents a weld line from being exposed right at the edge where it would be a fatal flaw to the cutting ability of the piece. Sometimes a flat core is sandwiched between two layers of lesser carbon, pretty, pattern welded steel (san mai construction). In the case of a kamisori, the tool maker might traditionally use a non hardening material like wrought iron and a small "tooth" of good quality steel for the edge.

There are a lot of variables to be controlled beside the steel choices. Heat history can be critical depending on steel type too. If the thin blade section is heated long enough, in the right kind of forge atmosphere, carbon can be lost to the environment and the decarburized area can be insufficiently removed during grinding. This might leave a section of the blade susceptible to crumbling or chipping. I have too many questions.