With lichee dye, for example, the color can be affected by the proportion of branches to leaves, by the season in which the branches and leaves are collected, by the intensity of the heat and the amount of time in boiling down the dyes, by the length of the soaking time for the cloth, and even by subtle differences between batches of raw fabric.
「植物染的變數很多」，張慧君舉例，是荔枝染，樹枝和葉子的比例，不同季節取得的枝葉，大火小火熬煮的間隔，浸泡的時間，甚至每一批不同的胚布都會影響染出來的顏色。