Well, the numbers on the blade are a quality control thing that helps the manufacturer correct and/or track down defects. (I could be snarky and say that good blades don't have numbers ). As for how long a blade "lasts." That is dependent on so many different factors. 1. How many passes per shave? 2. Thickness of stubble? (some people do have baby fuzz type hair. Others have copper wires for face fur). 3. Brand of blade? 4. Phase of the moon? Believe it or not, number 4 has the least effect on blade life. I'm above average, so I usually get 7-14 days out of a blade.
Various interesting answers, thank you - but one point nobody has answered is why with some makes there is 1 to 4 written on each cutting edge ?
They are tooling marks from the production line. If there is an issue in Quality control, the numbers help identify where the problem is.
They are used for keeping track of # shaves for me and thousands of other users, the new Astra SP blades are not marked at all with a # system to cut down on ink usage. More than likely used also for QC at the factory's. I like the # system but Kia blades do not use any markings, also other blades MFG's don't use it.
If im patient and take my time i have been able to get 15 plus shaves from a blade, but i enjoy using different blades so normally change out between 3 and 6. I dont flip the blade, i have no clue if it makes a difference. I tried palm stropping once and felt it dulled the blade.
Depends on your face and the blade. Strangely, I get the least use out of high $$ blades. Personna Crystals and Astras, will last me a week, or more, and still give great shaves.
I've been using several brands before ending up with Feathers. I use the blade 7 days, 4 days on side 1, 3 on side 2. (turn over on Friday, replace on Sunday) At the moment I just rinse the razor and store it. I don't loosen the blade, as shown in the informative video, as the current razor has to much play while tightening it. (awaiting a few replacements) Will loosening the blade while it dries really help, and switching sides every day? (has anybody experimented with that?)
I don't flip my blades and I simply use them until they start to tug and then they get tossed. For my face, if I cannot easily "buff", that's a strong indication that the blade is ready to go buh-bye.
Pretty much …. for me. I use the blade until it feels like it tugs then it goes. I find Astras last a shave or two longer than Feathers. I do take a blade out and let it air dry (blotting the excess water off with a tissue but not wiping the blade). I don't flip consciously but may do now and again as I just put the blade back in without thinking about it.