We produced some amazing work in my class Sunday November 6th, using the Serti technique to paint on silk. Serti is French, meaning fence; the resist line makes a fence to keep the dye in. Ideally, the dye goes up to the resist line and stops, making a sharply defined image. Without the resist, the line is soft, and if there is a hole in your resist fence, the dye will escape!
Sharpie permanent pens can provide a resist effect, though not as effectively as the Pebeo resist that comes in tubes from Dharma Trading. In this piece, Maya did the roses and butterfly first, using the Sharpie to outline before applying the rose colors with a brush. Then she outlined them with the Pebeo resist before painting in the black background color. The effect is stunning!
Ariel's Rainbow Dragon, done with the Sharpie pen for resist, is wonderfully enhanced by using salt to give texture to the background. Ariel and Maya both used Jaquard Red Label dyes, which are quite wet and wick through the silk quite a ways before "striking"--that is, stopping the onward march of color through the fabric.
The Sharpie pen is permanent; it will not wash out.
Dharma Pigment Dye seems to work better with the Sharpie pens as resist than the Jaquard dyes do, I think because of the solid pigments in it; it doesn't wick through the fabric as quickly. Even so, the Sharpie doesn't hold as well as the Pepeo resists do.
The white lines in this piece are the Pebeo resist. I use the clear, and it washes out easily in water. If you look closely, you can see where the dye escaped my fence! (hint--the green water lilies pads in front)