Naturally Colored Cottons

I went to Sheer Fun on the Farm at Meridian Jacobs farm in Vacaville and in addition to looking at all the cute lambs I was able to sit down with Sally Fox for a few minutes to talk cotton. She has been breeding naturally colored cottons for over twenty years and continues to develop new varieties of FoxFibre naturally colored organic cottons. I needed some additional technical information about colored cottons and Sally was happy to give me all the details on her varieties.

Traditional colored cottons are very short, they can be spun by hand but not with modern spinning machinery. The minimum length for commercial processing is 0.9 inch (23 mm.) The original varieties that FoxFibre cottons were developed from are 0.75 inch (19 mm) for brown and 0.9 for green. The Peruvian colored cottons available from some spinning suppliers are about a half inch (13 mm.) Sally's improved varieties are Coyote brown (0.95 in/ 24 mm,) Buffalo brown (1.1 in/ 28 mm,) Palo Verde green (0.95 in) and the new Sea Green (1.2 in/ 30 mm.) Sea Green is a cross with Sea Island cotton, a long staple variety. Nearly all cotton grown is some type of white Upland, Gossypium hirsutum, including the Acala varieties widely planted in Southern California. Sea Island is a type of G. barbadense, like Pima. Naturally colored cottons are such a small portion of the market that they are essentially not even considered by the commercial industry. Sally's fibers are also organically grown and processed.

In addition to selecting for longer fiber length, Sally's cottons are finer than average white varieties. To talk about fiber fineness, she first explained how cotton fibers are measured in micronaires. The developing cotton fiber is round but as it matures it collapses into something that looks like a squashed oval, it's cross-section is lobed with a narrow middle. This means it's not obvious how to measure fineness — which way do you measure it?

The micronaire, abbreviated m, was developed to take into account the various dimensions of the fiber cross-section. Commercial white Upland cottons are about 4 to 5.5 micronaire. FoxFibre cottons are around 2.5 to 3 m for greens and 3 to 4 for the browns. Large commercial growers select varieties for maximum yield and coarser fibers weigh more. They also dye more evenly, a desirable trait. This has resulted in average fiber fineness creeping up as growers get closer and closer to the accepted upper limit of 5 m for quality cotton fibers.

One interesting property of colored cottons is that they darken with washing. To speed the process, boil for 20 to 40 minutes. The water you use affects the color also, so it is best to boil all the yarn for a project at the same time. Green cotton looks nearly yellow when spun but boiling brings out a rich shade that seems it cannot possibly be natural. Boiling also removes the natural wax from the fiber and makes it more absorbant.

Her varieties are also stronger than the original colored cottons. Cotton fiber strength is measured in grams per tex, where tex is a unit of linear density (milligrams per meter.) The Coyote variety is an improvement over the original brown from 17 to 22 g/tex and Buffalo even more. Normal Upland cotton has a strength of around 33 g/tex.

Like any agricultural pursuit, the cotton business has it's ups and downs. Until recently, FoxFibre cottons were processed in the Bay Area by Athena Mills of Richmond but they have closed. For a short while, fiber could be found in a local surplus warehouse — a nice surprise for San Francisco handspinners but an unhappy business loss for Sally. She has continued to develop new plant varieties and this season is growing a crop for a Japanese mill. In addition to cotton, she is breeding naturally colored sheep to produce wool in matching shades of brown.

Naturally colored cottons for handspinning, yarns and fabrics can be purchased directly through Vreseis Limited, Sally's retail mail order business. Some handspinning suppliers also sell the cotton fiber.