Painting on silk is a unique art form. The colors and textures achieved are unlike anything else. It is a wonderfully fluid way to express yourself. I have briefly outlined the steps involved in silk painting. If you would like to try it, I would urge you to look at some of the many wonderful books on the subject. They will go into much greater detail than I do here.
THE FABRIC
Always start with white or natural silk that has been prepared for dyeing. The natural oils and gums have been removed, but no sizing or finishing chemicals have been applied. It is best to buy this from a company that specializes in fabrics for dyeing. Regular fabric store silk has been treated and will not readily accept the dye. Silk comes in many weights and weaves. To begin, it is best to use a smooth, lightweight silk.
THE SUPPLIES
There are many products available for silk painting. The traditional materials are French dye and gutta. I mainly use Tinfix and Super Tinfix, French dyes made by Sennelier. French dyes are for protein fibers, such as silk and wool. They come in an array of colors and can be intermixed for an infinite palette. Or if you'd like, you could mix all of your colors from yellow, cyan and fuchsia. French dye from different companies can also be mixed together. A mixture of distilled water and isopropyl alcohol is used as a dilutant.
Gutta is the resist used to form the lines on the silk. It is usually applied with a fine-tipped squeeze bottle. Resist acts as a barrier to the flowing dyes. Traditional gutta is a latex product and must be dry cleaned for removal. I use a water soluble resist called Resist Bein. After the finished painting is steam set, this resist is washed out in cold water. The downside of water soluble resist is that, unlike gutta, the dye cannot be painted over the resist line or it will leave a stain.
Clear resist and gutta leave a white (silk) line when removed. For variety resist is also available in black and metallic colors.
GETTING STARTED
The silk needs to be stretched tight and cannot touch the surface below. This can be done with a commercial stretcher, on a wooden frame, or across 2 x 4's clamped to a table. Either tack the silk edges to the stretcher unit, or hammer nails into the wood, every few inches and use heavy-duty thread to sew through the silk and around the nails.
APPLYING the DESIGN
You can work spontaneously and begin applying your design with the resist. But if you prefer to have more control and plan ahead, the design can be drawn on the silk using a disappearing ink pen. These are available at fabric stores. Be sure to use the kind that fades on its own, not one that has to be washed out. I use Dritz Disappearing Ink Marking Pens (they are purple). 
The lighter weight the silk is, the faster the ink will disappear, but you usually have a few hours. You can even draw your design in black ink on paper first and place it under the silk to be traced if you like. When you are ready to apply the resist, squeeze the bottle with the tip touching the silk. The resist must go all the way through the silk, otherwise the dye won't be stopped and will spread over the line. Be sure to let the resist dry before you begin painting.
PAINTING
My favorite brushes are natural bristles from Raphael's 800 Series, but I also use Chinese brushes and wide foam brushes for large areas. As you mix your colors, have a scrap piece of silk available for testing. The colors look much darker in the bottles than they do on the silk.
When you touch the dye-loaded brush to the silk, the dye will spread. It will take some practice to know how much dye to use and how close you can get to the resist line before the dye overflows. Colors can be mixed in the jars and to some extent on the silk as you paint. The dye dries quickly and if a wet edge meets a dry edge a dark permanent line will appear. This can be used as a design element if you are aware of it, but to avoid it, work out from the wet areas and carefully plan your design so there are no large awkward spaces to try to fill in.
Some special effects can be achieved with isopropyl alcohol, water, and salt. The alcohol or water can be dropped from an eyedropper or splattered on the dry areas of the painting to produce lighter spots circled in a darker ring. Salt can be sprinkled on wet areas to create a swirling, textured design. The salt absorbs some of the dye to create this look. Experiment with different size salt granules and different colors. Some colors and brands react much more than others.
FINISHING
Once the painting is completely dry it can be unstretched. If it gets wet at this point it will cause running or staining, so be sure your hands and the table are dry. Unless you used one of the new silk paints on the market that doesn't need steaming, the dye now needs to be steam-set. You can buy a commercial steamer, follow directions for steaming in a book, or obtain detailed directions for stovetop steaming from Dharma Trading Company. After steaming, the water soluble resist is washed out in cold water and the silk is ironed while still damp.
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