Name: Carol
Message: I am wondering what dye is used on fabric that when dyed and laid in the sun, develops the dye color. If patterns are put over the fabric, then that part remains lighter or white. This is used making the Hawaiian sarongs or pareos.

There are three different ways to color fabric permanently with sun-developed images.

The easiest is actually sun painting, not dyeing. You saturate fabric with transparent fabric paint, arrange objects on the damp fabric, then expose the assemblage to the sun or any hot lamp. It is actually the infrared light (radiant heat) which does the trick. Exposed areas dry first, in the hot light; the drying exposed fabric sucks additional wet dye out from under whatever you have placed on top of the fabric. The result is lighter-colored 'shadows' wherever you placed the masking objects. The color is deeper where the light from the sun, or the hot lamp, was able to reach. It is not the ultraviolet in the light which does the work, but instead infrared, so a halogen lamp is more suitable than a fluorescent sun lamp. This procedure has been widely popularized for use with Seta Color brand fabric paint; for example, see the Klutz book of Sun Painting, entitled "Sun Paint: Use Sunshine to Make Colorful Fabric Prints". However, the same technique can be used with other brands of thin, transparent fabric paint, as well; for example, PRO Chemical & Dye provides instructions for "Sun Printing using PROfab Textile Paints". This is a highly suitable project for children and beginners.

Another method of sunprinting is to use Inkodyes. These are a type of dye which is chemically similar to vat dyes, but instead of being applied in an oxygen-free bath and being developed in the fabric by exposure to oxygen, Inkodyes are developed by light. Inkodyes are true dyes, not fabric paints. (A dye actually itself attaches to the fabric; fabric paint includes a glue-like binder, which imparts a stiffer feeling to the fabric.) The process is more difficult than the process of tie-dyeing with fiber reactive dyes. The only known retail source of Inkodye is Dharma Trading Company. Jean Ray Laury's book, Imagery on Fabric, provides information on how to use this type of dye.

A third method is to use blueprinting, or brownprinting, using exactly the same photographic techniques used in making architectural blueprints, in which fabric is treated with two chemicals, ammonium ferric citrate and potassium ferricyanide. Sometimes you can find pre-treated fabric, which simplifies matters drastically. The treated fabric, whether purchased pre-treated or prepared in the darkroom at home, must be stored in a light-proof bag. Working quickly, but not necessarily in the dark, you arrange your stencils or objects on the treated fabric, then expose it to the sun. A book on how to do this is Barbara Hewitt's "Blueprints on Fabric: Innovative uses for Cyanotype". The technique is also covered in Deborah Dryden's "Fabric Painting and Dyeing for the Theatre". The resulting fabric, or garments, can be washed by hand, but should not be line dried out-of-doors, since extended exposure to the sun will encourage fading. Blue Printables sells treated fabrics (and at least formerly also sold treated t-shirts), as well as chemicals for preparing your own fabric.