How do the manufacturers "test" their DE and disposable blades?

[MuzzleVelocity]

One of the things I find so frustrating about trying different honing methods is that there is no unbiased, scientific, quantitative way to "rate" the resulting sharpness. HHT varies immensely by the person's hair, among other factors.

Then you inevitably hear that the only "real" test is the shave test. But once again, its purely subjective. Human beings doing research inevitably (and subconsciously) lean towards finding what they want to find. Its like the audio-phile who swears that his $10,000 "oxygen-free copper" speaker cables just simply "sound better" than regular cables....

But anyway, I was wondering if anyone has ever had any experience in one of the factories where DE or disposable straight blades are manufactured. Surely they must have some sort of impartial test to determine if the blades being spit out of the machines are up to specification.

I remember seeing a discovery channel show called "World's Sharpest" and one of the things they showed was an aparatus for testing and rating the sharpness of various kitchen knives. The machine would press the knife into a stack of paper until it cut through it. By measuring the force exerted on the knife the sharpness could be rated. Also, by repeating the test numerous times they could rate which knives would stay sharpest longest.

[mdunn]

they probably did all kinds of tests way back when to design the blade and work out manufacturing technique, but now only do QA by looking at them under a microscope and seeing if they look the part.

[Sticky]

This link is a bit dated, but it says that hair was one of the methods used to test razor blades during manufacture (as was a variation of "optical flat" techniques).

[Lesslemming]

I recall having seen a documentary film on TV about the production of DE blades.
The quality control took a couple of DEs out of production and simply ran it through an REM (or similar) microscope
with an extremely high resolution. The man behind said something like
"look, under this magnification you still can see some unevenes in the edge"
(he was talking about (very) little waviness and some plastic flow on the very edge
that is of no consequence to the shaving experience)

A DE production is in many ways unsimilar to sharpening razors.
If you sharpen a couple of razors you have a huge amount of variables
that will change during the session. The pressure you apply, the width of the bevel etc...
A DE production is a continious process with close to none variables.
The pressure the sharpening machine applies is always the same,
the blades always have the same withs and so on.
That´s why if you get a DE production to run perfectly
you will hardly ever get different results.

And for the info, DE and other disposable producers do test-shave!

The razorbladeindustry has been working on stuff like this for decades.
They spend unbelievable amounts of time and money into inventing
new sharpening devices and such.
I feel sorry that I have no insight into this kind of knowledge.
What do you think they found out during 20 years of research?

IDK. But I know that the width of the very edge can be measured via REM( or better SEM).
This will give a very good clue of what will shave good.
We only look at the face of the edge, the bevel, when looking into a microscope.
SEM pictures can be taken from the top of the edge.
An average edge with is 0.35µm, gilette once said they made a 0.1µm blade

[Seraphim]

How do they test for sharpness?



By shipping it to you, the customer.

[JimmyHAD]

Years ago I read that Gillette had a cadre of individuals ..... I don't know how they were selected .... that they would send razors and blades to. I can't recall where I read it or when it was that I read it ( a couple of decades ago for sure) but these people were part of the R&D of Gillette's product line for both razors and blades.