For fiber reactive dye (Procion MX): 1–2 teaspoons (4–8g) of dye powder per 240ml of warm water for medium intensity. For dark colours, use 2–4 teaspoons. For pastels, use ½ teaspoon. Dissolve in a small amount of warm water first, then dilute to final volume.
Mix 35g (about 9 tablespoons) of soda ash per litre of warm water. Soak fabric for at least 20 minutes, then squeeze out the excess without rinsing. Soda ash raises pH to 10–11, which is needed for the fiber reactive dye to permanently bond with the fabric.
Fiber reactive dyes work best on 100% natural fibres: cotton, rayon, linen, bamboo, and silk. Polyester doesn't absorb these dyes. Cotton/poly blends will dye but the colour will appear lighter. Pre-wash fabric before dyeing to remove sizing and improve dye uptake.
Urea is a humectant — it attracts moisture and keeps the fabric damp during the dye reaction, giving more time for the chemical bond to form. It also helps dissolve dye powder more completely. Add 15–30g per litre of water. It's most useful in hot or dry environments.
Wrap your dyed project in plastic and leave it for 24–48 hours at room temperature. The longer you wait, the more vibrant the colours. After waiting, rinse in cold water until the water runs clear, then rinse with hot water, then wash separately with detergent.