Cut up Tansy flower tops and soak overnight in water (pond or river water if available).
Boil up in stainless steel pan; simmer for an hour or more until water is well coloured; then leave to cool to hand hot only. (Cotton can be simmered, but silk may get matted and rough if boiled).
Agitate silk in dye bath occasionally, redistributing evenly in liquid during first 15 -30 mins to ensure all areas are covered when first absorbing dye. After first absorption, remove to a china or glass bowl, to agitate easily. Use an upside down lid to keep silk beneath surface.
Transfer boiled liquid from steel pan to bowl for easy silk soaking and ocassional moving for even dye distribution.
Soak silk for some hours in cooled dye bath liquid. The colour of the dye bath water is no indication of the final outcome on dry silk. Remove soon if you want a pale colour; leave overnight for stronger colour.