Giddy-Yap Lucy (Coloring Book Page)

Maybe fifteen years ago I won an auction for five I Love Lucy coloring pages. I am pretty sure I didn't spend more than 25 bucks for the lot. But I love the work so much. The unnamed artist has so much control of his line and really gets the anarchic side of Lucy. I don't know why I kept on forgetting to put this last page on the site. For those completists out there, forgive me.

But do me a favor friends. Please. Help. I have asked before and got crickets. What the hell is the red around the characters. I am sure it has something to do with reproduction and production but what? Someone out there has to know. I have a few coloring book pages that has this and I would just like to understand what the processes were. If you know, let us all be smarter. Thanks.