There are many reasons that you might want to paint on sheer fabric, even though it's not the most obvious choice as a painting medium. Sheer fabric can be used for clothing, curtains, tablecloths and other household, personal or school projects. Painting on a sheer fabric often requires the use of either paint or dyes and sometimes both.
Preparing your Canvas
Any sheer fabric, be it silk, chiffon or rayon, must be stretched over a canvas before it can be painted on. This doesn't have to be a conventional stand or wooden frame. You can use any firm, flat surface as long as you have a way to fasten the fabric to it securely. Be cautious with fabrics such as nylon or rayon that may stretch during this process. You may want to stretch your fabric so the designs you paint on it shrink or change shape, but be careful that you alter the canvas evenly to avoid any unpleasant surprises after you unfasten it.
Paints and Dyes
Acrylics and special textile paints (or dyes) are the best choices for painting on sheer fabric, but if you have other water-based paints that you would like to use, just mix them with some acrylic paint or fabric dye. This way you can also make any colors that you might not be able to find ready-made. Wet on wet techniques, like those used in watercolor painting, are also commonly used when painting on sheer fabrics, in particular by silkscreen painters.
Borders and Fences
Any medium you choose to paint on will require you to use a medium such as wax or rubber to make a border before applying any colors. Sheer fabrics have virtually no absorbancy, so without a border or fence, your colors will run. Wax crayon is the cheapest and most accessible option for most, but other options include liquid rubber or petroleum jelly. Making an outline for your dye or paint will also help you do a first draft of your design.
Choosing Your Fabric
Sheer fabrics come in many colors and varieties, and some are easier to paint on than others. Beginners might prefer something with a higher thread count, such as silk, which will take a smoother and more even coat of paint. If you're using muslin or cotton, preshrink your fabric by washing it in hot water. This will ensure that no dust or lint is on the fabric to allow smooth application of the border medium and your choice of paint or dye.