Bright chrome finish, popular on automobiles bumpers and trim, is applied through a process called electroplating. Chromium, and other metals, are plated onto steel and other base metals, to prevent corrosion.
Bare metal parts are placed into a tank containing chemicals that include ions of the metal to be plated. The parts are hung from racks connected to a DC power supply; metal rods in the bath are also connected to the power supply. The application of current causes the metal ions in the solution to deposit out on the work pieces.
A metal plating shop specializing in chromium plating ran three (3) shifts. The night shift's production was always superior, despite only having one (1) operator doing the work of two (2) people. After spending the night observing the third shift operator, the owner did not find anything extraordinary. But the chrome finish was not as bright as previously produced.
Why was this one operator producing more than the other two shifts and what was different when the owner was present?
Here's the rest of the story.
The owner went back to observe the following day, but this time he hid in the shadows so the operator would not know he was there. The operator, who now thought he was alone, walked over to the big chromium plating tank, unzipped his pants, and urinated into the plating bath.
Once confronted the operator apologized profusely, pointing out that he couldn't leave that plating line alone so when he had to "go", he would urinate into the tank.
The next day, the owner called a plating consultant and told the story of the night shift operator. I'll bet its urea, exclaimed the consultant. Sure enough, urea and its cousin compounds are plating brighteners.
And so today, many plating baths contain urea.