A few months back, having mostly given up on my Gillette Mach 3, I decided to go all old school and get myself a safety razor. While I cut myself occasionally (one day I cut myself right on my Adam’s apple, giving me a minor scare that I’d slit my throat), I’m significantly happier with the results of this razor, compared to the Mach 3.
I find that I need to shave only a single time, compared to two rounds with the Mach3, and cleaning the razor in the middle of the shave is also far easier. And while it isn’t absolutely smooth, it leaves me mostly satisfied at the end of the shave. And I’m not even mentioning the cost saving here!
The only “problem” with using an old-school safety razor is that it takes in double-edged blades. Having used multi-blade cartridges all my shaving life thus far (my father had bought me a Sensor Excel when I was first ready to shave, which I later traded for a Mach3), I started using a single side of the blade to complete the entire shave.
In my experience, a decent blade should last about 6 shaves, as long as you use both edges of the blade equally. The challenge here was to know (visually) which side of the blade you had used, so that you could get the maximum out of the blade!
Initially I thought of using stickers or some such paraphernalia to indicate which side of the blade I’d used each time. After a little thought, however, I realised that if this was a common problem, the razor itself would’ve come with an asymmetrical head, so I could keep track. There should be a better way to keep track, I reasoned.
And so I decided that I would use each edge of the blade half-and-half in each shave. The first day, it worked. The second, I had finished shaving half my face, when I realised I’d suddenly forgotten which side I’d used. An improved method was required.
So the solution I’ve finally hit on is to randomise the edge of the blade I use each time I rinse my blade in the middle of the shave. So each time I rinse the blade, I give it a random twirl, and use whatever edge that twirl turns up for my next set of strokes. And so forth. This way, in terms of expected value, both edges of the blade are likely to wear by a similar amount by the end of each shave!
And so if I find one day that an edge is blunt, it is highly likely that the opposite edge is also as blunt, and it is a clear indication to put in a new blade!
It is remarkable how so often randomised algorithms can help you trivially solve problems that cannot easily be solved by deterministic methods!
Interesting use of randomization. This made me think about another problem and was wondering if you have any thoughts on it:
Let’s say I have around 40 T-shirts – from which I have to select one when I step out of home. I maintain this as two “columns” on a shelf in my ward-robe. I am mostly a top-of-the-shelf guy (with little to no fashion sense for this analysis). When I wash my T-shirt, I immediately get it pressed and place it -yes, at top of one of the two columns in the shelf.
The problem is that – even though the population of T-shirt is large – I end up wearing a subset of it (say:10) in a given quarter. What algo to use to make the usage optimal ?
Interesting question. I guess the problem is that you use a stack, and because of that the same T-shirts keep getting reused. I have this suggestion – everytime you add T-shirts to the stack, flip the entire stack! That can kinda turn the stack into a queue and your problem will be solved!
Speaking of which, have you seen the “pancake flipping problem”?
https://en.wikipedia.org/wiki/Pancake_sorting
Thanks 🙂 . This pancake flipping problem is awesome. Will try this the next time I need to set my t-shirts 🙂
One more place where this probably has more applicability is for inner-vests (mostly-homogenous-color) – and also because it’s bought as a pack (And not loose additions like t-shirts).