Nylon is preferred by people not only because is it strong but because it is a lightweight fabric. It can absorb moisture and yet dries easily, and it is easy to care for. Paint dries easily on it as well. Applying paint to nylon fiber can be done two ways, either by painting it on or by dyeing the fabric.
Wash the fabric to make sure no dirt is in or on the fabric. Washing also gets whatever shrinkage is going to occur out of the way. Do not skip this step even if the fabric is new. If you can, dry the fabric outside, under the sun; or just leave it out to air-dry.
Pin the fabric on a flat surface. Any material needs to remain still while being painted on. Placing wood or cardboard underneath the nylon fabric to avoid staining the other side is also a good idea, especially if the fabric has been sewn into clothing.
Draw the pattern on the nylon fabric.The pattern will serve as an outline minimizing any mistakes. Using a paper stencil will make the job easier and faster. Fill the spray bottle with paint and lightly spray paint on the nylon fabric.
Dip the brush lightly in the paint. Painting on nylon fabric is no different than painting on canvas. Follow the pattern drawn on the nylon fabric. Brush the excess paint lightly using a toothbrush. Paint tends to stiffen fabrics. Be careful not to use too much paint. When enough paint is on the brush, paint in one direction. A sponge will be useful, especially in areas where the brush is not practical, especially on the edges. You can avoid excess paint outside the outline if you use a sponge.
Hang the fabric up to dry. It is better to air-dry it. Do not touch it to test if it's dry. If you didn't use excessive paint, it will be completely dry after one to two hours under the sun.