How Marbled Paper Book Covers Were Made
Remember those books with swirly, patterned plates on the front and rear covers? Here's an awesome short film about the Cockerell Bindery, which produced marbled paper in a surprisingly handmade process. It's beautiful, retro, and super-British. If you just want to see the color marbling process itself, zoom ahead to 3:00 and watch the colors being applied.
This is one of those things I never thought to wonder about, but seeing it happen, I'm astonished at the craftsmanship involved. Humans are amazing. Enjoy:
If you're interested in creating marbled paper, here's a tutorial covering various methods.