In addition to the tech it publicly releases, Apple invests in some pretty wacky technology most people never hear about.

One example? The half a gallon of synthetic sweat it produces every single day to test its products to see how well they’ll withstand the day-to-day rigors of everyday use. Yes, really!

The intriguing tidbit was shared by Vice journalist Arielle Duhaime-Ross as part of an article exploring Apple’s environmental efforts.

On Monday this week, Duhaime-Ross visited Apple HQ, where she was shown Apple Watch cases and AirPods placed in containers filled with synthetic human sweat to make sure they’re safe to wear over long periods of time.

To be clear, Apple’s doing nothing fundamentally different by doing this. Sweat testing is used in many, many different manufacturing sectors, ranging from jewelry and clothing to cosmetics, leather manufacturers, and credit card companies. Doing so allows companies to test products for possible harmful or unsightly corrosion, or to test the “colorfastness” of dyes and materials used in the production process.

There are even companies like Pickering Laboratories in Space Park Way, Mountain View, which specialize in working out perfect formulas for synthetic sweat. What differs with Apple, as befits a company that has sold upwards of 1 billion iPhones, is simply the mind-boggling scale that it’s carried out at.

We presume the job of whoever produces Apple’s fake sweat will find themselves even busier when Apple finally gets its proposed sweat sensor working for a future Apple Watch…

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