Thread: I need advice on a crumbling edge.

God bless your efforts, it seems like everytime I run into this stuff its on an older razor( Ithink its due to the older forging processes) and the only thing I can do is to keep honing until the bad metal is gone. And some of these are WORK!

Thanks again Bart. You do a grand job. If needs be just be aggressive with it. Perhaps its a learning exercise for everyone. Whatever the case, dont beat yourself up about it and if you get sick of it then just send it back. I dont want to be making you tired of honing or even taking up your time.

Why not use 4 or 5 layers of tape now until you get it back into good metal. Then remove tape and do a final reset with a single layer or maybe 2. If you have to have that angle to keep it from crumbling then the steel is still no good and it won't hold up anyway.

One thing I'm curious about in general. Do you have a micrometer? If so, next time you change tape can you measure the spine thickness at a few spots without the tape and then measure again with all the tape? Not to find out how thick 3 or 4 layers of tape are but to find out how evenly it's possible to apply it. Electrical type tape stretches very easily (decrease in thickness). You're going to stretch it by simply removing it from the roll. Then you're going to stretch it (or "bunch" it up) again during application and smoothing it on. I'm wondering how much variance in thickness results from this? With more than one layer I'd expect this effect to be magnified.

That's a valuable suggestion, honing with a steeper angle till I strike sound steel.
I was too optimistic last night. Honed some more today, to deal with the neglected tip, and all I found was more crumbles... But there is noticeable improvement, compared the the initial condition.

One of my problems with this job is tool related. My DMT-C and F both have lapped a vast amount of Coticules, and although not completely worn out, the diamonds have been tamed seriously.

More work tonight. I'm going to take your advice on the tape.

Speaking about tape: you're right. Not only because it introduces unevenness at the spine (The spine of the W&B is very uneven to start with), but also because multiple layers introduce a clear cushion effect, preventing any crisp keenness if you apply the least pressure. The solution is to use aluminum tape underneath one layer of electrical tape. (Oddly enough the electrical tape seems more wear resistant than the aluminum).

Thanks for the good observations,
Bart.

Interesting thread. So it's possible to hone an absolutely crisp bevel on both sides but have a corroded "bubble" encased in seemingly sound steel?

I'm in no way suspecting that whoever restored the blade ruined the temper on a portion of the razor. I can only share a personal experience. When I first built by abrasive belt grinder and took it for a test spin I selected a Dahlgren Swedish steel razor as a sacrificial blade and ended up ruining the temper on the toe half of the razor. The edge portion (extending approximately 3/16" up from the edge) would even crumble to light touch. It would crumble away. The steel in that area with the edge so thin was unmistakably brittle.

If you showed me that photo and described your difficulties based only on my experience (limited experience, yes so take FWIW) my opinion would have been temper issues not knowing about corrosion, etc.

Chris L

Thanks, Chris.
I don't know the cause either. Too bad no one came up with a reliable test to discern between temper and corrosion issues. But I think the course of action to deal with both problems is the same: removing steel in the hope that the problem is localized enough to get past it.

Bart.

One thing I noticed in examining the temper ruined razor I spoke of is that pressing the damaged edge portion of that razor head on and perpendicular to the edge of my thumbnail showed that my thumbnail easily pressed into the edge damaging it. Crumbly is the best descriptor. I corroded edge that apparently can appear to be normal I would think would NOT yield so easily to a fingernail, etc. On a corroded edge that "good" steel is still tempered. You may want to try, under low magnification, pressing the edge into something like a pin in an area known to have given you problems. I would argue that if anywhere along that area, the edge crumbles, I don't think corrosion is the problem with this razor. Just a guess.

Chris L

I've been around that razor long enough now, that I don't need to try. The affected part of the edge crumbles even from doing a HHT.
But I 'm not sure about the premise that only steel with messed up temper would display that behavior. I think it also depend on how the temper was ruined. If overheated steel is quenched immediately, it could be brittle. If not quenched, it could be annealed (too a degree) and overly soft. I'm certainly no specialist in this field.
If I've understood the various posts in this thread well, then also corrosion can take different incarnations.

Bart.

Hello Bart,

ChrisL just brought this thread to my attention. It has been a very interesting read, especially about the hidden corrosion.

In the case of a wedge about the only thing to do is exactly what you have already done. Breadknife, set bevel up to 8000, if chipping occurs the go back, breadknife, set the bevel up to 8000, if chipping occurs, breadknife etc.
I do agree with the use of 3 layers of tape on the old wedges. The spine thickness usually has been severely compromised.

There is no easy way out of this, it is just plain grunt work.
It sounds like you are almost done. Keep trucking!

Two things:

Firstly I should like to speak up for and reiterate what I think has been said already. The restoration was done by a very well respected member of the SRP community. He has told me he did nothing to affect the temper of the blade and thats good enough for me. I hold his handywork in high regard and feel the problem here is 100% to do with the steel itself. It has nothing to do with and SRP member here.

Secondly- Hooray for Bart! I recieved my first two razors in the post today- the Dovo Black Star and the mystery titanium one. Bart, I too am suprised at the titanium one! I did a TPT on it and it sliced clean through my thumb pad! And the Dovo is also the first razor I have actually witnessed passing a proper genuine HHT in front of my eyes. I'm about to go shave with one for the first time but all the signs are good. I will report back afterwards though.

One question remains: What was that stuff you packaged it up in? It looked like something like a curtain rail!