Weld also known as Dyers Rocket is a hardy biennial that produces attractive flat rosettes of long slender leaves throughout its first year and long, tall spikes in the second year, growing up to 1.5metres. It flowers between June and August and is also an excellent plant for attracting wildlife.
The highest yield of dye seems to be obtained from weld which is grown in alkaline soil and low in nitrogen. The seeds are very small and need light to germinate. The plant does not transplant well, so ideally the seeds should be sown in their flowering position in late summer or early spring, by preparing a fine tilth and sowing the seeds thinly on the surface of the soil.
To Harvest Weld
Cut the plant about 10 days after the start of it flowering. The leaves, flower heads, and seed capsules provide the maximum dye content. The plant can be used fresh or dried for storage to be used at a later date.
Weld is a Mediterranean herb that was used by the Romans to dye the robes of the Vestal Virgins. With alum mordant weld produces an outstanding primary yellow on wool and silk. Weld over-dyed with woad makes Lincoln Green which was the colour of Robin Hood and his merry men’s clothing! Weld is the yellow that all other yellows are judged against. The substance responsible for this yellow is luteolin.
To dye with weld
On alum mordanted wool, weld yields a light fast yellow.
- 200g of fresh weld or 100g of dried weld
- 100g of alum mordanted fibre or yarn (dry weight.)
- 10 litres of water
- 4g of chalk (calcium carbonate)
- 12 litre stainless steel bucket
If using dried weld soak it in the dye bucket overnight in the 10 litre of water.
If using fresh weld – chop and cover it with the 10 litres of water and simmer for an hour. If you live in a soft water area add the 4g of calcium carbonate to the water as weld performs better in hard water conditions. Allow to cool and then strain off the juice – this is your dyebath.
Meanwhile, soak the fibre or yarn to be dyed and leave for several hours – until you are ready to dye – at which point, squeeze the fibre/yarn and add to the dye pot. Slowly bring the dye pot to simmering point for about an hour. Gently move the fibres around from time to time, but do not agitate. Turn off the heat and allow to cool overnight.
Rinse in tepid water until the water runs clear and then wash gently using a mild liquid soap followed by a final rinse.
The dye remaining in the dye bucket can be used again to produce lighter shades of the same colour before it becomes exhausted.