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Comment by 4death4 | Hacker News Reader

The coolest thing I've learned from this article is that road signs have a retroreflective coating on them. In hind sight, it makes sense: you always notice the signs light up as your drive by but don't necessarily notice the signs light up as others drive by. But it's not something I've ever really thought about.

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I saw someone with a running jacket that had something like this the other day. From a distance they shone like a road sign, but as I drove past them, under the street lights their jacket looked a medium grey.

I thought this was a pretty cool technology as in my country people like to wear dark clothes, and at night they are basically invisible on the road (lots of residential areas don't have street lights). A law was brought in a few years ago that pedestrians walking at night need a reflective band, but most people don't care.

3M and I think others make black retro reflecting stickers that turn silvery when reflecting at night. Craft and vinyl cutting machines can turn them into shapes, numbers, etc. Motorcycle riders will sometimes use them on their helmets or motorcycles which is how I came across this 25 years ago.

Motorcycle Black Reflective Tape 3M Scotchlite™ DYI Kit ME RK-99 https://a.co/d/2pNM5Js

It's been a clothing trend for awhile now

If you have access to laser pointer, shoot one at a road sign. They'll light up from many hundreds of meters away.

Make sure no one is behind you though, I have heard of people being pulled over for doing that due to inducing temporary blindness at night.

Technology connections has a good video about retroreflectors https://youtube.com/watch?v=Bi_Tp1H9CDs

The effect is particularly impressive/pronounced if you walk around with a headlamp (like literally a light on your head, as you might use when camping).

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