Thread: Is "Resting a blade" complete bull?

Originally Posted by Phoenix51

Any thoughts on whether or not to tape the blade while it is resting??

VHS is a good bet (cutting edge!), but resting razors tend to remain rather inactive for a while (pining for the fjords), so some sort of time-lapse might be in order.

Regards,
Neil

Originally Posted by Phoenix51

Any thoughts on whether or not to tape the blade while it is resting??

Might be a boring video.

Bob

I am going to mention something my brother in-law told me. For reference he is a metallurgist at Northern Illinois University. When I asked him what tempering steel was all about he told me this. That steel has residual stress when put out of position by outside forces. When steel is heated and forged or taken out of its original shape when it was heated that as it cools there is tension in the material, and when the steel is heated back up to 'X' percentage of the melting point (I can't remember what he said that was) for a certain time it restores a balance to the steel taking out that tension. Kind of similar to how an extension chord that's been rolled up for a while wants to stay wavy when you unroll it until it sits in the sun or heat for a bit and "relaxes" then at the end of the day it wants to stay straight. (this analogy may only make sense to those who have used them in the colder months) Based on that I would think that the edge when shaved with and minimally put out of position, will have stress put on it causing it to re-align itself to a degree and there is stress in the material of the edge until it has sometime to get back into position. You can also see this on a large scale if you have ever seen a large flatbed semi trailer get unloaded. Those are made with arced beams that flatten out when loaded up and when that stress is taken off the bed it flexes back to the arced position. Maybe that's what is meant by letting it rest. I don't know. Take it for what it's worth.

Originally Posted by JazzWillie

I am going to mention something my brother in-law told me. For reference he is a metallurgist at Northern Illinois University. When I asked him what tempering steel was all about he told me this. That steel has residual stress when put out of position by outside forces. When steel is heated and forged or taken out of its original shape when it was heated that as it cools there is tension in the material, and when the steel is heated back up to 'X' percentage of the melting point (I can't remember what he said that was) for a certain time it restores a balance to the steel taking out that tension. Kind of similar to how an extension chord that's been rolled up for a while wants to stay wavy when you unroll it until it sits in the sun or heat for a bit and "relaxes" then at the end of the day it wants to stay straight. (this analogy may only make sense to those who have used them in the colder months) Based on that I would think that the edge when shaved with and minimally put out of position, will have stress put on it causing it to re-align itself to a degree and there is stress in the material of the edge until it has sometime to get back into position. You can also see this on a large scale if you have ever seen a large flatbed semi trailer get unloaded. Those are made with arced beams that flatten out when loaded up and when that stress is taken off the bed it flexes back to the arced position. Maybe that's what is meant by letting it rest. I don't know. Take it for what it's worth.

So, do we let the blade, "fin" for 12-24 hours or strop that puppy silly right after shaving with it?

I have stropped my razors post shave for as long as I have been using straights. Works just fine for me. YMMV.
I certainly can understand Dovo and other manufacturers recommending blade rest periods
and I would say the same if I were trying to sell you another razor to use while one rests.
Better yet I would try and sell you a 7 day set. : )

Originally Posted by JazzWillie

You can also see this on a large scale if you have ever seen a large flatbed semi trailer get unloaded. Those are made with arced beams that flatten out when loaded up and when that stress is taken off the bed it flexes back to the arced position. Maybe that's what is meant by letting it rest. I don't know. Take it for what it's worth.

True but a 3" razor isn't gonna change its shape to the degree a 60 foot flat bed will or it would imply that the razor is not tempered correctly.

One tool you will see change it's shape is the dual sided Japannese knife. The iron & stel laminates have different qualities & sometimes you need to restraighten these a few times.

I guess I might as well toss my 2 cents worth in as well.

Finning does exist. You can experience with a bow saw on a cold day.
While in your nice warm house where you keep yours saws carefully protected, sharpen the teeth and make sure the teeth are all in line (which I'm sure that everyone does ). Afterwards, you can run your finger down the side of the blade and it is smooth. Let it sit outside for about 15 minutes in near freezing temperatures, then run your finger down the side of the blade and you will feel that the teeth have shifted. Go cut some nice green wood with the saw to the point where steam is coming off the wood and run a gloved hand down the side of the blade again. Different teeth will have shifted. Now take the saw back into the house and lovingly clean and polish it. If you run your hand down the side of the blade you will still feel teeth out of alignment. Wait 24 hours and run your hand down the side of the blade again and it will be smooth and the teeth all aligned.

If you listen closely to some old "singing" saws, you can hear teeth ping as they settle back into position during cool down.

Now, does this affect razors?
Without going into metallurgical detail and phase diagrams and all that mechanics of materials stuff...
At worst, my razors see water temperature extremes from 65 to 120 degrees F and the blade itself may go from 72 to 105 degrees F. I don't think the temperature swing is enough to cause the fins to move more than a nanometer or two. So I don't worry about my blades resting.

Step back in history 100 years or more and consider Solingen in the winter, in an unheated bathroom, and shaving with hot water - yes I believe that the fins would move a micron or two and that could eat a strop and stropping could actually break the fins off leaving a rough edge. So resting the blade would have been a good idea.

Maybe Dovo should consider updating their instructions every century or so?

And now I feel compelled to take a microscope with me when I go on vacation this winter to see if this happens. I can't wait to hear what my wife says about my shaving addiction then...

I don't rest my razors intentionally but they all have 9 days rest on my rotation (i have 10 razors on my rotation - 1 in use and 9 at rest) but i do 20 passes on leather strop after shave to dry the edge of the blade. I don't see any problem doing this.

Originally Posted by onimaru55

True but a 3" razor isn't gonna change its shape to the degree a 60 foot flat bed will or it would imply that the razor is not tempered correctly.

One tool you will see change it's shape is the dual sided Japannese knife. The iron & stel laminates have different qualities & sometimes you need to restraighten these a few times.

The steel would still have the same amount of ability to flex per inch though wouldn't it? I.e. If we made a 3" trailer or a 60' razor the 3 trailer would have the same amount of flex as a razor and vice versa?

I forgot to mention it earler in all the excitement, but my favourite razor is actually taking a good long rest right now.

It booked itself a 119 day long cruise on Fred Olsen line to see all the wonders of the far east.

I had been working it hard, to be honest.. It recently sent me some delightful photos of itself on The Great Wall of China, and the change in it is quite remarkable. It had been developing a slight frown, but in the photos it is sporting a wide smile.

Upon my word, the rest has worked wonders on it!

I am now a firm believer in metal realignment and the benefits of resting a razor...

Regards,
Neil