Basically my question consists of the title and the addtional query ‘How was/is this done?’. I have seen such a pattern most often on wrapping paper and the side and endpapers of Webster’s Dictionary (a rather large unabridged edition in some library).
An example of the pattern can be found on the wallpaper at this link: http://www.thefleetwoods.com
That’s “marbleized paper.” We used to do it in grade school. Here are some simple instructions - you can use any color paint you want, really, of course, not just their red and green.
Two ways I can think of to do that ( I don’t know of any special name for it).
Just warp some lines in photoshop.
Lay some lines of thick heavy paint down ( in the example in a upper-right to lower-left direction), then use a stick or something to drag the paint around. You would curve the lines you were making to get the pattern shown there. Tempera ( poster paint) or plain old house paint on wood, ( you want to paint on something that won’t absorb the paint too well) would probably be best for doing that effect.
I used to restore antique books. Take them down to individual pages, wash them and sew them back together again prior to binding. Sometimes the ‘end-papers’ on the original binding were marbled so the new ones were marbled too.
I’m afraid I can’t remember the exact details but basically it was oil paints, any choice of colour, blobbed onto a tray (cat litter tray is ideal) of water. (You can add some wallpaper paste to the water for increased viscosity.) COMB the paint gently into swirls, using any suitable tool, then place paper on top.
The paper is best lowered gently, you should hold both ends, one lower than the other, with a slight sag to it. Make sure the first end to go on to the mix is lifted (v gently) before the last end has touched the surface. Be as smooth as poss with this ‘curving’ action to avoid ‘smudges’.
Have fun.
In Japanese, it’s called suminagashi.