Long-handled string bags dyed with natural dyes including, madder, burnt ash, and sea salt. Botanics range of string bags is dyed using natural organic materials such as pomegranate, sea salt, and the madder plant. Why are natural dyes better? natural vegetable dyes are nontoxic and biodegradable. Please note: in the absence of the chemical mordants the vegetable dyes will fade in time and may stain light-coloured clothing. As a precaution, it is advisable to wash before use.