this post was submitted on 23 Jun 2025
387 points (93.5% liked)
science
21630 readers
469 users here now
A community to post scientific articles, news, and civil discussion.
rule #1: be kind
founded 2 years ago
MODERATORS
you are viewing a single comment's thread
view the rest of the comments
view the rest of the comments
Not plastic caps, plastic paint. The printing on bottlecaps is a polymer and it gets scuffed.
Odd. I would have thought that the paint, being on the exterior, wouldn't leak into the beverage contained inside the glass.
But apparently, they found that blowing air over the caps reduced the amount of detected contamination by 60 per cent. So it seems like an easy fix that manufacturers can implement inexpensively (literally just an electric fan)
There is a real reason that the caps are painted. Glass beverage bottles are usually stored in a crate and grabbed from the top, so the design on the lid is what restaurant or store employees used to distinguish what drink is contained within it. This allows employees to distinguish similar-coloured drinks (e.g. Coca-Cola vs Pepsi or two different brands of beer) just from looking down at the top of the bottle.
But there probably is a way to paint them without using plastics
Then stamp/engrave the caps paint isn’t needed
Which is easier? Squatting down to count how many caps say "Coca-Cola" or counting the number of bottles with red caps?
Put a sticker on it after it's sealed.
The reason for paint is because the cheap, mild steel they use for bottle caps will begin to rust in minutes - literally minutes - if it is not protected from the oxygen in the air. The paint is necessary to keep the caps from oxidizing and leaving rust marks on everything they touch.
The color and logo on the caps are simply for marketing purposes.
Unfortunately, it's probably not going to be an electric fan, but compressed air. Even more unfortunately, compressed air turns out to be a major cost factor due to the cost of running compressors, which might prevent adoption.
The original paper mentions blowing the caps out with an "air bomb", which I'm pretty sure is a mistranslation stemming from the French term "Bombe d’Air Comprimé", i. e. an air duster, a can of compressed air. In an industrial setting, you'd use a compressor for this, naturally.
How exactly would that happen if the cap is ON the bottle?
You make a lot of them. They are flat. They get painted, they get punched out, (this is where the ‘magic’ happens) they get shuffled around to load into machines to put them on the bottles, they go through the machine and they get clamped to the bottles.
There! Instant plastics!