Usually, when you place your brush on the silk the paint/dyes spread uncontrolled. Unless there is a resist line, the color won't stop. But you could spread some kind of substance on top of the silk to slow this process. These substances are called antispreads or antifusants. When antispread is painted on silk and let dry before applying the dyes, it will stop the flow of colours. The silk becomes almost like a piece of paper, and the dyes can be painted directly on the silk without using gutta or other type of resists. Very detailed works with no outlines can be achieve by this method.
Jacquard's No Flow
Paint this onto your silk and let it dry before using any silk dye. It's like painting on a primer and then painting over it with your dyes. The dyes will now hold their line without spreading across the fabric. You can now paint without any resists. Washes out easily with soap and water. Can be steamed but a little harder to get out afterward. Works with all dyes. Some artists use primers like this so they can paint their signature in a corner of their piece.
Sennelier's Stop Flow
Call it what you will, it is painted onto the silk (and dried) before the paint or dye, which it then keeps from spreading when it touches the silk. The dye stays put where you want it instead of wicking all over the place. Allows for freehand painting without Gutta or other resists to "fence" the dye. Think of it as sizing to prep the canvas with. It washes out with water in the end. This is the only one that can also be used with flowable paints like Dynaflow and Setacolor.
2M Antifusant by Dupont
(Not available in the U.S.) Antifusant 2M is made of Essence F (a solvent) and can be applied on white or coloured silk. It does not effect or change the colour of already painted silk, and it keeps its soft hand and brilliance.
Solvent Based Antispread
You can make your own 2M Antispread by mixing Essence F plus Essence F-based gutta, or any other solvent-based gutta plus its solvent.
1HO Antifusant by Dupont
Antifusant 1HO is water based and should be used only on white silk.
Water Based Antispread
You can make your own 1HO Antispread by mixing water based gutta plus water.
Magic Sizing (a fabric finishing spray similar to spray starch) can be sprayed onto dry stretched silk. Once evenly applied, the surface can be air dried or set with a hot hair dryer. Painting on the finished surface is much like painting on watercolor paper.
Very little dye is needed and dry brush techniques are recommended as the sizing works as a ‘stop flow’ . It fills in the fibers of the silk and prevents the dyes from flooding the surface. A stiffer brush may be used to ‘scrub’ the colors into the surface of the silk.
For use in smaller areas, such as reflections, the sizing can be sprayed into a glass and brushed on to selected areas to protect the white surface.
After setting the dyes as recommended by your particular dye, the Magic Sizing washes out of the finish work leaving no film or thickness to the dye.
Anti-spread by Beatriz Castro