1. Fill a plastic container with one gallon / 3.78 liters of water.
2. Add one cup soda ash and stir.
3. Completely submerge your pillowcase cover or linen into the container for 15 minutes.
4. Wring out the linen and empty the container.
5. Add a dish drainer or drying rack (we used a letter tray) on top of the plastic container.
6. Lay the pillowcase or linen onto the drainer or rack. You can bundle it up depending on desired design effect.
7. Completely cover the pillowcase or linen with ice cubes.
8. Using plastic gloves, start applying the cold water dye over the ice cubes. Add less for more of a watercolor effect or more dye for more vibrant colors.
9. Once the ice is completely covered in dye, let it sit for 24 hours.
10. Wash and dry the pillowcase or linen as usual.