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Comment by pbhjpbhj | Hacker News Reader

It's a shower proof seal for a toothbrush, literally just need an o-ring, you know like the one that keeps the water in the pipes. The parent said the old one had a replaceable battery and worked for 10 years, seems like they had already solved the water ingress issue.

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Yes, but you never used those old style electric toothbrushes in the shower right? An O-ring would just confer water resistance, not water proofness. You couldn’t really submerge it and expect it to continue working. There is a huge difference between hermetic sealing an an O ring or a gasket.

I washed my old toothbrush. It gathers toothpaste gunk if not properly washed. It worked just fine for a decade. The motor finally gave up.

No way is this new tooth brush going to last me 10 years.

And people making excuses - do you know that kids electric tooth brushes have replaceable batteries? Shouldn’t that be a bigger problem? Here’s the kicker - kids electric tooth brushes don’t have replaceable brush heads.

Yeah - this is nothing but planned obsolescence.

Kids toothbrushes aren’t designed to be used in the shower.

As a child, I had a $20 plastic submarine that was powered by AA batteries. It could sit at the bottom of a pool for days on end, without water ever getting into the battery compartment of the engine module (which was sealed with a rubber o-ring).

I bet there are hundreds of counter-examples to your claim that water-proofing with an o-ring is an engineering challenge of the utmost difficulty.

> An O-ring would just confer water resistance, not water proofness.

The comment you replied to explicitly said:

> > an o-ring, you know like the one that keeps the water in the pipes.

> You couldn’t really submerge it and expect it to continue working. There is a huge difference between hermetic sealing an an O ring or a gasket.

No, there isn't. O-rings and gaskets are exactly what one uses to make stuff waterproof.

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