We use the RIT brand of tie-dye. Below are the instructions from their website on setting the colour to prevent it washing out:
- To help set the dye, we recommend using your microwave. Wrap the dyed fabric in plastic wrap and seal the edges. Place the wrapped fabric on a paper towel in the microwave and heat for 1 to 2 minutes. Plastic will puff up, creating a heat chamber that helps bond the dye with the fabric. Once the microwave is done, remove the fabric and open the plastic, letting it cool down.
- Rinse in cool water until rinse water begins to run clear.
- Hand wash in warm water with a mild detergent, rinse and dry.