Color, also called hue, is your crayon box. It is the rainbow plus all those earthy tones and any other one you can imagine.
I am not going to take on the impossible task of presenting an exhaustive study of color in weaving. Whole books have been written on color and color theory, even one specifically for fibers entitled Color and Fiber (Lambert, Fry and Staepelaera, Schiffer Publishing, 1997). I highly recommend this book for a thorough treatment on the subject.
If you are not familiar with, or own, a standard color wheel many can be found on the internet much like the one shown here. These can be very useful when planning hues for a project. Find the link to one here: Color Wheel
There are some basic hue combinations:
Complementary (hues opposite each other on the color wheel)
Split complementary (choose a hue, go to the complement and instead of picking that hue, go to the ones on either side of the complement)
Triadic (hues that form an equal triangle, using the points to pick the colors)
Analogous (hues next to each other on the color wheel)
Analogous with central color complement as accent (this is one of my favorites. Choose a set of analogous hues and also the complement of the middle one)
Warm colors (hues on the yellow, red, orange side)
Cool colors (hues on the green, blue, purple side)
Bluebonnet towel made with analogous hues of purple, blue and red with a
slightly yellowed-green as accent.
One thing you will want to watch out for in hue interactions with fibers, is putting two or three together that will gray out when seen from a distance. How does this happen? A hue mixed with its complement will gray (or make a muddy brown) visually. For example take a red warp and a green weft in plain weave. When seen up close you may see the red and green but move back from it and the hues blend visually to create a new hue. If this was your intention, fine. If not then you may want to separate the hues by using stripes or some other weave structure. I have an example of this effect from my own work. I made a weaving with surface pleats where the pleats transitioned from purple to green and the base cloth transitioned from green to purple. The weft I used was fuchsia. When viewed up close it is fun to walk from one end to the other watching the hues shift. The work, however, is large and when I stood back to photograph it the transition effect is lost and the entire work takes on a gray cast.
Here you can see the hues blend and gray-out when seen from a distance.
In the close up view you can see all the hues clearly.
You may be limited to the yarn hues commercially available unless you dye your own yarns and fibers. In the past several years I have used fewer and fewer commercially dyed yarns and have not purchased any. I prefer to dye my own and buy standard size yarn in either natural or bleached white. There are several reasons I choose to do this. One is my extensive use of 20/2 and 10/2 cottons. The 20/2 especially is getting difficult to find in a wide range of hues. Another reason is that I can produce the hues I want for each project without having to wait for an order to come in. I also dye my yarns so that I can make the quantity of yarn I need or the special effect I want in a yarn without having to purchase large quantities.
This summer Tien Chiu has been blogging about color in weaving as well with some terrific examples and advice. I recommend you visit her site and see what she has to offer. You can find the link by clicking on her name above.
When thinking of hues to use in a project one thing I do is look at my collection of images. I began this collection years ago on the advice of a professor. First you find and old book. Then you collect images from magazines and elsewhere and cut and paste them in the book. The only requirement is that you are, in some way, drawn to the image. You add no comments or doodles. Gradually this collection grows until you have a handy reference and can see trends and themes develop. If you do not have such a reference I recommend beginning one now.
Four color, network twill with echo. Warp is yellow-orange and navy, weft is red and light blue.