1. Dyeing wool and silk with weld (Reseda luteola L.) Maarten van Bommel Marjolein Groot Wassink

2. Weld dyeing Recipe: - Lab recipe or original, 17th century recipe? - Mordants used? - Conditions applied? Do you want to obtain a specific colour or a reproducible recipe?

3. Weld dyeing Material Weld (Reseda luteola L.) from Anjou (south of France) - 10 kg - Chopped plant material Stem Leaves Flowers No roots How to sample! - Deionised water was used - Chemicals of analytical grade

4. Weld dyeing Lab recipe based on historical recipes - Both wool and silk were dyed - Only alum was used as mordant - Variation in the use of potash (potassium carbonate) - About half of recipes found described the use of potash to “extract the dye from the plant”

5. Mordanting Recipe: - 10.3 gram alum - 3.44 gram cream of tartar - 2.5 litre water - 50 gram silk For wool all values were doubled. - Boil for 1 hour - Cool down - Rinsed in streaming water Samples were taken prior to and directly after mordanting

6. Dyeing Wool Silk - 50 gram weld in cotton bag 37.5 gram weld - 6.25 gram potash 4.69 gram potash - 2.5 litre water - boiled for 30 minutes - remove dye bath from heating point - add 50 gram wool 25 gram silk - allow dyeing for 30 minutes under stirring - take wool out of dye bath and cool down - heat dye bath to boiling - remove dye bath from heating point - add the wool - allow dyeing for 15 minutes under stirring - take wool out of dye bath and cool down - rinsing with streaming water

7. Weld dyeing Without potash With potash

8. Weld dyeing With potash Without potash

9. Samples distributed - Untreated silk - Untreated wool - Washed wool - Mordanted silk - Mordanted wool - Wool dyed with weld - Wool dyed with weld and potash - Silk dyed with weld - Silk dyed with weld and potash - Plant material from Weld In addition, samples were taken from the dye bath during dyeing and analysed at ICN

10. Samples distributed Partners - OADC - KIK / IRPA - NGL - UNI-PG - ICN - GCI - NMS / UoE EU-Artech partners External partners

11. Main issue’s remaining - How can you sample the plant material in a homogeneous way prior to dyeing? - How do we store these reference materials? - How long are these materials guaranteed? - ?