About the same weight or twice as much as the fabric
The root of Murasaki, a perennial herb found in Japan, China, and the Amur region, is called Shikon (purple root). Designated as an endangered species in Japan, the root contains a purple pigment called shikonin. Purple was historically prized as a rare purple pigment, the highest on the Twelve Steps of the Crown. Fastness to sunlight is rather weak.
Soak in methanol or ethanol at room temperature overnight, strain through a cloth, and dilute with water. Although suitable for aluminum mordant dyeing, the dye is at 60-70°C because the dye changes at high temperatures. Alkaline treatment (5% soda ash solution or lye) after dyeing gives a bluish-purple color.