Wash and dry the cotton fabric for the batik technique. Cut out sections for each child of about 1 foot square or larger.
Cover a table in plastic. Anchor the cotton pieces onto the plastic with masking tape to reduce the chance of slippage.
Pour water-based resist into a squeeze bottle and cap it securely.
Draw the outline of shapes onto the dry cotton square with the resist. The resist covers lines of the fabric and prevents the dye from coloring these areas, thereby producing designs and color differences on the finished product.
Paint over larger areas that should remain white with a paintbrush dipped in the resist. Let the resist dry for the time specified on the product.
Dilute one or more heat-set dyes with water if desired to achieve a particular intensity of color.
Dip another paintbrush in one of the heat-set dyes and apply it onto the surface of the fabric. Cover as much area as desired. It is not strictly necessary to color between the resist lines, as the white outlines will show up after the process is finished anyway.
Add in extra color if necessary with another paintbrush dipped in another color of heat-set dye. Keep colored areas separate, or blend them together in whatever manner is most appealing.
Allow the dye to dry for the time specified on the product instructions.
Sandwich the finished fabric between two sheets of parchment paper and apply heat from an iron.
Fill up the sink with water that is not too hot to touch, in case burns occur.
Soak the fabric in the sink until the water-based resist comes off the fabric. The dye may run into the water, but this normal.
Rinse all of the excess dye and resist from the fabric with clean, cold water, and hang the material up to dry, or dry it in a mechanical dryer.