Making hand-dyed shirts with food colouring can be an enjoyable activity for small children or an economical way to brighten up some of your old shirts. Food colouring is safe for kids because it's non-toxic and washes off their skin more easily than fabric dyes. Food colouring is inexpensive and dyeing clothing with it is easy because you do not have to put the dye through the washing machine or in a special colour-safe container.
Check the label on the shirts you want to dye. Do not use food colouring to dye cotton, acrylic or polyester because these fabrics won't hold food colouring, and the colour will come out when you rinse it or get it wet. Food colouring also doesn't work with linen, rayon or hemp. The dye will adhere well to wool, silk and nylon.
Mix a 50-50 solution of water and distilled white vinegar in a spray bottle. Spray the shirt all over to dampen it with the vinegar solution. The shirt should be wet to the touch but not drippy.
Lay the shirt in a large, shallow microwaveable bowl or dish with the side you want to dye facing up. Don't use a plastic dish because the colour may not come out of it after microwaving. Decorate the shirt by applying the food colouring directly to the fabric. If you want to decorate other parts of the shirt, use the tongs to turn it around.
Dye the whole shirt one colour by mixing about 2 cups of vinegar with the food dye in the bowl. Add enough dye to get a dark colour (at least 20 drops) and press the dampened shirt into it with the tongs. Let the shirt sit for a few minutes, stirring it gently with the tongs to spread the dye evenly. Lift the shirt out to check the colour. If it isn't dark enough, wring it out into the bowl (wear gloves if you don't want to dye your hands), add some more food colouring and try again.
Cover the bowl or dish tightly with the cellophane wrap and put it in the microwave. Turn the heat on high and heat the shirt until the cellophane starts to expand at the top. This should take at least 15 seconds, though it could take longer. Turn off the microwave as soon as the clingfilm/cellophane starts to expand to avoid drying or burning the shirt.
Take off the clingfilm/cellophane and allow the shirt to cool completely. When it's cool, rinse it in cold water until the dye stops running out.
Wash the shirt in cold water on the gentle cycle or hand wash the shirt when it gets dirty. Wash the shirt as little as possible to make the dye last longer.