The painting above was done on silk treated with an antidiffusant instead of using a linear resist such as gutta. This allows you to paint in a watercolor-like fashion .I use Jacquards No-Flow antidiffusant, which is a heat tolerant starch that stiffens the silk making it more paper-like. This makes the silk easier to draw on and also adds resistance to the dye spread so that you can paint in a more watercolor like fashion. You must be careful not to get the silk too wet, drying each layer of color with a hair dryer before adding the next or you will lose the antidiffusants ability to act as a resist. You also will lose some of that wonderful blending quality you get with untreated silk and have to work a little harder carefully wetting down small areas that you want to blend without getting the silk so wet that it bleeds into other areas. You will also not be able to get as good results on treated silk with salt and alcohol, although the alcohol will work better than the salt.
Some people use a spray starch called Magic Sizing, I tried using regular starches from grocery stores with mixed results. Because I steam my silk pieces twice the starch I use must be very heat resistant or it will scorch leaving a yellow cast to the silk, so far Jacquards product is the only one I have found that leaves no cast to the silk after steaming as long as you steam for no longer than two hours per steaming.
Jacquards antidiffusant will wash out with hot water and laundry detergent. It sometimes leaves a very slight feel but I am not that fussy about rinsing because I am framing all my work so if you wash carefully I think you could remove it all. As with all of the highest quality silk painting products it is expensive but to me it is worth the price for the effects it produces. It available through Dharma Trading: http://www.dharmatrading.com/.
This painting also was created using an antidiffusant. The only linear resist that was used was the outline on the water and white resist to preserve the snow on the branches of the evergreens. Even the small trees were painted using just a very dry brush on the treated silk.
