Weld - Reseda Luteola is also known as Dyers Weld, Dyers Rocket, and Dyers Mignonette produces an excellent light and washfast yellow and is a strong clear yellow to combine with indigo for emerald and leaf greens. It is traditionally cultivated throughout Europe as a yellow dye plant it still flourishes on embankments or beside railways and roads. Weld gives strong intense yellows which are clear and bright. The strength of these colors makes weld a good choice for over dyeing with indigo to obtain teals and greens. can be dyed at 30-50% WOF for a medium depth of shade.

Mordanting: 

• Protein Fibers: use alum mordant at 15% WOF
• Cellulose Fibers mordant with tannin at 8% WOF and then alum at 15%, or alum acetate at 8%.

Dyeing: pour boiling water over the plant material and allow to stand overnight. Add more water and bring the pot to a simmer but not more than 160 F as too high a temperature will dull the yellow. Strain off the dye liquor into the dye bath. The plant material can be reuses two or three times for light shades. Add the fiber to the dye bath and simmer below 160 F for about one hour. 

Weld develops best in slightly hard water. Adding finely ground chalk (or a Tum’s tablet – 1 to each 4 liters of water) brightens the weld color, especially if there is no lime in the local water.