Weld

Weld (Reseda luteola), gives an acid yellow, depending on the mordant or olive greens with iron added.

Weld gives  a superb bright yellow rendered almost luminescent by a touch of ammonia (or stale urine if you are striving for authentic touch of the mediaeval dyer). With Indigo it gives  a wonderful lime green with one dip or a bright green with two. Weld is one of  the most lightfast of yellows and is an ancient dye – seeds of the weld plant have been found in iron-age sites, although it did not reach the UK till the 12th century.

Weld (Reseda luteola), gives an acid yellow, depending on the mordant or olive greens with iron added. It can also produce a grass green when over-dyed with Indigo or Woad.