Numbers on DE blades

[abj]

Some blades have numbers on it. 1 & 2 on 1 side, 3 & 4 on the other side.
What's the use of it? First I thought to see which side you're using. But when in the razor you can't see those numbers.

 

[Bogeyman]

Manufacturing reference numbers.

 

[abj]

Thx

 

[Crossroads]

Some blades have numbers on it. 1 & 2 on 1 side, 3 & 4 on the other side.
What's the use of it? First I thought to see which side you're using. But when in the razor you can't see those numbers.View attachment 41679

A DE razor blade in practice has four cutting edges, place in your razor with 1&2 showing- after two shaves flip it over and rinse it, then you are ready for shaves 3&4. I use this method myself, which is why I prefer a razor with a butterfly opening, a Gillette Adjustable Fatboy 1959.
I read about blade flipping on a shaving forum, very likely this one, about a decade ago.

 

[chris.hale]

A DE razor blade in practise has two cutting edges.

The numbers are for quality control at the factory.

 

[Woody72]

Why would having identical numbers on every blade have anything to do with quality control?

 

[Blademonkey]

Why would having identical numbers on every blade have anything to do with quality control?

Because there are four grinding wheels grinding the blade as it goes through the line, in QC if they find one of the grinds are bad they can look at the number and check the correct grinding wheel. P.

 

[chris.hale]

Because there are four grinding wheels grinding the blade as it goes through the line, in QC if they find one of the grinds are bad they can look at the number and check the correct grinding wheel. P.

Exactly.