I’ve been using fountain pens for a long time, but I only recently began to appreciate ink. Yes, there are more colors than black and blue-black.
One of the more difficult thing is to choose a color that actually pleases you. Of course, you can browse online stores to get ink, but the colors presented in the swatches are not all that fateful to the actual color you will get out of your fountain pen. Sometimes you have a nice surprise, sometimes you’re disappointed.
Anyway, while exploring the colors, I’ve decided to keep record, and to this end I’ve devised a simple template for swatches that you can download in french or in english (both are released under the WTFPL).
The best way I found so far of making a good, uniform mark is to use a Q-tip, soak it fully, and paint the paper as uniformly as possible. Voilà, you’ve got a record of that color. Keep in a dry place, away from light.
The three good sources for ink I use are The Writing Desk in the UK, Goulet Pens in the US, and stylo.ca in Canada. I really like all three of them, they all give excellent service, and the first two are family businesses.