Why are there colored dots on my soda can?

Most people have noticed that soda cans and other containers (tubs of yogurt, for example) frequently have a series of small, colored dots on them. Since I was a very young kid, I’ve wondered what those dots were for. I hypothesized that, since the colors of the dots were usually similar to the colors on the container, they must have something to do with the printing process. But I waited until grad school to find a definite answer.

Soda Can Dots

I was standing at a reception with a bunch of classmates dressed in suits. We were waiting for a lecture by some Public Administration big-wig. And somebody was drinking a can of Pepsi. I looked over, noticed the dots on the can and thought, “Yeah, what are those?” I threw the question out there. So, we did what any self-respecting American would do – we got on the phone and called Pepsi’s customer service line. They were ready with a quick answer, so they must get the question a lot…

Turns out, the dots are part of the printing process. Each color applied to a container of food is put there by a separate ink-spraying machine. Each of these machines applies the appropriate colors for the product design, and then sprays on a simple colored dot. It may do this in an inconspicuous part of the main label (as seen above), or sometimes even on the bottom of the container. This makes it really easy for employees to figure out what’s happening if the container designs start looking funny. Instead of having to go to every ink machine to check if it’s out of ink or malfunctioning, they can simply pick up a misprinted container, check to see which dot doesn’t look right, and go fix that machine. It’s a pretty cool and simple solution for making manufacturing quality control that much quicker!

Interested in learning more? Nordson is a company that makes some of these ink-application machines, and their literature for their Ink-Dot I.D. System has some pretty interesting facts about the process.

Also, I went looking for a YouTube video of this process in action. Though I did find video of labels being rolled onto cans, I couldn’t find any videos of the ink-spraying system. But the YouTube search results included this video, which it would be morally irresponsible for me not to share…

2 Responses

  1. Masood Mustufa January 4, 2018 / 8:28 pm

    I was also looking for answer.


  2. Frank Roberts December 11, 2018 / 8:30 pm

    The colors are register marks. They’re used to keep all the different print in the proper location in relationship to the other colors. Electronic eyes scan for them and if they’re out of place , either sideways or “running” register , the machine will make adjustments to correct.

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