Copyright infringement vs. public domain images

[Onboard 2.0 9083]

Wondering if any Surly lawyers can explain how you determine if an image is copy right protected or public domain.  

A few friends are creating a T shirt for a local festival, and want to use an image of an old 60's TV character (Floyd the Barber).

 I don't really know how you go about even finding that kind of info.  I've seen his likeness on dozens and dozens of items, shirts, mugs, posters, etc from many many different sellers.  The printer says we need a release to use his image to avoid copy right infringement.

Edited February 21, 2020 by Onboard 2.0

[Hornius Emeritus 12801]

Not a lawyer, but this guide will help you immensely.

https://blog.kenkaminesky.com/2017/07/27/how-to-legally-use-copyrighted-images-infographic/