Wasn't me saying "plastic, what could go wrong." But, yes, re: boiling metal.
Let's look at this from a chemical perspective. Unless you add a solvent to the water, boiling a metal razor for 5 minutes will not react with the metal. It's chemically impossible.
Now, if you insist on adding a solvent to the water, all bets are off. But, plain liquid H2O, no matter how hot it is, will not damage a metal razor.
Think about it from this perspective: what causes the most damage to metal over time? I'm going to bet that the main factors causing damage are from chemical reactions- especially from perspiration- and friction. After all, now matter how insignificant the chemical reaction from perspiration + damage from friction are in the moment, the combined effect of each over literally decades is likely to cause some change in the metal. Boiling metal for 5 minutes will not damage it. What it will do is kill any bacteria that may have built up over the decades.
Now, could you use something like rubbing alcohol or the like to disinfect a vintage razor? Of course. Clearly, you would prefer this approach. As for me, boiling is both less expensive than buying a bottle of rubbing alcohol for each time I buy a new razor, and I'd say that using any solvent is likely to react more with the metal than boiling water.
Note: the above comments apply to stainless steel and other metals that do not oxidise easily. Obviously, were a razor made of, say, wrought iron, this advice does not apply. Not sure I've ever seen a wrought iron razor, though. And, equally obvious, boiling a razor constructed of material that does not stand up to heat- for instance, plastic or wood- would be inadvisable.
Clean and sterilize tools - Hesperian Health Guides
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