Blues Brothers,
Cars, Cars, Cars.
To understand Fender custom colors you have to know what the colors are based on. The answer, of course, is automobiles. Cars in the United States had more social influence than just about anything at the time (even more than Elvis). Fender's only in-house paint mixes during the 50's and 60's were Sunburst and Blond (and Candy Apple Red to a point: more on this color later). All other colors originated directly from the cars of the time, and most of these colors were from General Motor's cars.
Let me back up and tell you exactly how I researched this. I've been doing car and guitar finishes since I was in high school. And I constantly get guitar clients asking for the wide array of Fender colors that were offered during the 1960's. But I always turned them away from doing all colors except those I could accurately reproduce: white, black, and blond. After all, white is white and black is black, and everyone has seen a million blond Teles. It's pretty hard to screw up those colors. Finally I decided to do some research on the other colors.
The first step was to look at the original Fender custom color charts. If you don't have originals to examine, use "the Fender Stratocaster" book (new edition) by A.R. Duchossoir, page 31. Thanks to the 1960 color chart, Fender provided us with the manufacturer, type and paint code for every color on this chart (though it's not obvious).
Take the first color, Lake Placid Blue, for example. The paint type is "Lucite", which is DuPont's brand name for acrylic lacquer. The number, 2876L next to "Lucite", is the DuPont paint code identifying the paint formula for Lake Placid Blue (note some colors are "Duco", which is DuPont's brand name for their nitrocellulose lacquer).
If you bring the paint code 2876L to your local DuPont automotive paint dealer, you can identify which car originally used this color. In Lake Placid Blue's case, that would be a 1958 Cadillac color available in acrylic lacquer (Lucite).
But you say, "acrylic lacquer? I thought Fender used nitrocellulose lacquer?". Fender used both acrylic and nitrocellulose lacquer in the color coat. To understand why, we have to understand what the difference is between acrylic and nitrocellulose lacquer.