Mask & Paint
Your fabric needs to be mainly natural fibre (a small percentage of lycra will be ok), this technique won't work on synthetic fabrics. We've used a beautiful NZ Merino Wool for our leggings.
Start by masking out the design. We have taped the side panel of the ooh la leggings to brown paper. You can play around with different widths and spacing of your tape to create the design you want.
We have just used normal black acrylic paint and mixed it with a textile medium. Put two parts paint to one part textile medium. Mix together.
Start painting making sure you get a good coverage.
If you want to use a light colour, you need to mix with an opaque white fabric paint along with your textile medium.
Paint onto remaining sections.
Leave to dry, or if you're in a hurry like I always am, dry with a hairdryer.
Peel off masking tape.
Once it's completely dry, heat set your design by ironing for about two minutes. You might want to test first on a painted scrap piece to find the temperature that will work for your fabric. The textile medium will make your painted area slightly stiff but this will soften up after washing. Voila!