Woad: Sarah's natural colour

Dyeing with woad

Dyeing with woad powder or dyeing directly with the leaves

Woad is like other indigo dyes.  The pigment is insoluable in water and must be reduced to a soluable form before it can be used to dye fabric, yarn or fibre. Dyeing with woad powder: To do this make a stock solution in a 1 litre glass jar: Grind the pigment with a stone mortar and pestle as finely as possible. Add to jar and make a paste with 1 tbsp. of water and 20 grams of indigo powder (or use the amount of powder that you have -- other chemicals remain the same) Fill jar 3/4 full of hot tap water (130F) Add 2 tsp. (10 grams) sodium carbonate (soda ash) to raise the pH to 10 Add 1 tsp.(5 grams)  thiourea dioxide as the reducing agent Stir and allow to sit 1 hour to reduce.  You will see a change in the colour of the liquid.  The liquid will turn from blue to brown or green and a foam of blue will float on the top of the jar.	20 grams of indigo may be extracted from 5 kg. of woad leaves harvested in July to September, using my innovative extraction method.
Fill 1/2 full  a separate dye vat with hot water (50C ) Add 1 tsp of thiourea dioxide (5 grams) Add 1 tsp. sodium carbonate (5 grams) Cover and allow to reduce 30 minutes	Dyeing directly with the leaves After extracting the indigo from fresh woad leaves follow the steps through to the oxidization phase.  Instead of waiting to allow the indigo to sink to the bottom follow these steps:   Omit the sodium carbonate, if your vat pH is 10. Continue as for dyeing with woad powder.
Add jar of stock solution to the prepared vat by lowering the jar below the surface of the vat and pouring out gently. Its important at this stage to avoid introducing oxygen to the vat.
To begin dyeing, enter prepared fiber, fabric or yarn into the dye vat.   Wait 15 minutes.  Remove the dyed article, being careful not to introduce oxygen into the vat.  Squeeze excess liquid out close to the surface of the vat to avoid splashing.  The dyed article will be a pale green colour as it rises out of the vat .  It will change to blue as it is exposed to oxygen -- the magic of indigo. Allow the article to oxydize for a full 15 minutes. Enter it into the vat again for 15 miinutes.  And again oxydize for 15 minutes.   Continue soaking in the vat and oxydizing for 15 minute intervals until the desired shade is reached. Indigo dyed tetiles are more colourfast when vatted and oxidized several times to build up the layers of colour rather than using a strong vat and dipping only once or twice.
For paler blues plan to dye the article at the end of your dyeing session, with an almost exhausted vat. The colour is more fast if it is dyed many times with oxydization rather than dyeing only once to the correct shade.
Indigo forms a mechanical bond with the fiber, rather than a chemical bond.  It builds up on the surface of the fabric like bricks and each dip in the vat increases the depth of the molecular structure on the fabric surface.  The more the depth of this molecular layer of indigo, the more resistant it is to rubbing off. Blue jeans are often dyed only once or twice in a very strong indigo vat to take advantage of this property of indigo and increase the worn out look of abused denim.