While I'm on the topic, here are a couple more examples of color shifts/changes within printings of color illustrations in the Oz books.
One of the best known changes is in The Emerald City of Oz. The earliest printings used an additional color of ink, green metallic, on the color plates to help create an Ozzy feeling. Later printings dropped the extra ink, leaving white areas within the plates. Fortunately, in most cases the green ink was used as a minor embellishment, and the images hold together quite well. In some cases. you actually see more detail without the green ink.
In the case of the illustration to the right, dropping the green ink meant losing the border of the image. This isn't a vital part of the illustration itself, but there is a lot of humor in the missing words. To the best of my knowledge, illustrator John R. Neill devised the nonsense words himself, without the assistance of L. Frank Baum. It reads:
Soandso, and soandso, oh yes, I don't know it might be so I calculate but I don't know, intre mintry cuteycorn appleseeds and fly away Jack. Six sixes are not sixty-six? And we still hold to folderol de doodle all day, if I had a donkey that wouldn't go I'd buy a fiddle for fifty cents and rattle his bones over the stones it's only a beggar whom nobody owns, listen??
The character shown talking to the Wizard is from Rigmarole Town, where people talk in circles. I think Neill grasped this pretty well!
Ozma of Oz was printed with color illustrations for many years, and there is a definite shift towards brighter color in later editions. Shown above are the frontispiece from a first state copy (left) and a 1920's edition (right). Ozma looks like she's been in the sun a little too long in the later printing, and can sometimes be very blotchy. Part of the reason for this is that the early printings were on a smoother paper stock. By the 1920's, the Oz books were being printed on a much pulpier paper which soaked up more ink, resulting in brighter and harsher color.
In the image to the right, a similar result can be seen with the earlier plate on the left and the later on the right.