Things You'll Need
Whitener and brightener fabric dye
Rubber or latex gloves
Broomstick or wooden spoon
Large glass, steel or plastic container
Many items glow fluorescent under a black light, including special paints, dyes and laundry detergents. With supplies from a grocery store or a home improvement store, you can treat fabrics such as cotton so that they glow when exposed to a black light. Dyes designed to whiten and brighten can be used to treat fabric as an economical alternative to purchasing specialized black light paints.
Follow the manufacturer's instructions to determine the amount of whitener and brightener dye necessary for the amount of fabric available. One dry packet of dye is used per pound of fabric, instructs RitDye.com.
Fill a container with lukewarm water, and pour the whitener and brightener dye into the water. Use enough water to cover the amount of fabric.
Place gloves on your hands and stir the water with a broomstick or a wooden spoon to fully combine and dissolve the whitener and brightener dye.
Place the fabric into the container of water, and allow it to saturate. Use the wooden spoon or broomstick to stir the fabric through the water, ensuring an even level of dye throughout.
Allow the fabric to soak according to the manufacturer's instructions. The fabric may be soaked for up to 4 hours if desired.
Remove the fabric and wring it to remove excess moisture. Dry the fabric outside on a line or hung in the bathroom so that any drips do not alter carpeting in the home. Fabric treated with whitener and brightener will glow a bright blue-white color under a black light.
A washing machine can be used for large amounts of fabric. Use the agitate setting to stir the fabric, and allow the machine to go through the rinse cycle when completed. After the fabric has been treated, run the washing machine for an empty cycle to remove residue.