The first dye plant we tried at Armley Mills was woad. Someone later commented that this was like starting at the back of the chemistry book –going right in at the deep end. The benefits of being based in the Industrial Museum meant we got a lot of very helpful advice. I have a clear memory in my mind of looking despondently at the dye pot thinking it had failed to work –only for one of the resident felt makers to hold the pot up to the light and point out the blue particles precipitating out of the solution. Despite woad being tricky it is definitely worth the effort. The numerous colour changes that occur during the reaction make it a definite spectacle.
We used Jenny Dean’s method ; but after numerous searches of supermarket shelves concluded that old fashioned colour run remover no longer exists. We substituted it for a chemical reducing agent brought from an online natural dye website.
The process starts with picking a large amount of green leaves. Somehow, possibly due to the Braveheart movie, most people seem to know that woad is blue. So when picking woad leaves it is very tempting to inspect the leaves to try and see any hint of the blue colour in the green leaves. The leaves give little sign to being the only blue dye producing plant in the British Isles. How anyone ever discovered woad is lost in the mist of time. Traditional woad production involved the use of stale urine –which smelt so bad that during Queen Elizabeth I time there were laws banning woad production within four miles of any royal palace .
The modern method does not smell particularly foul. The leaves are stewed to make a sherry coloured liquid; which with a few additions and a lot of shaking of the jar (adding oxygen) turned blue. The addition of another chemical turns the solution yellow. While the solution is in the yellow state the fabric is added. Only when the fabric is removed does it turn slowly, and slightly magically, from yellow to a beautiful blue (the magic ingredient is the exposure to the oxygen in the air). The never quite knowing if it has worked until the end adds a level of suspense –and a desire to show off the finished fabric.
Woad like all natural dyes is seasonal. To get the best blue colour you need to pick the first-year woad leaves when they have had maximum sun exposure (August/September time) but before the frost which saps the blue colour. You can make the woad solution and store it, but somehow part of the magic is being able to go from fresh green leaves to blue fabric.
Woad blue was eventually surpassed by indigo from the Americas and then by synthetic indigo. In the UK it was still being grown in East Anglia and being used as a component for the blue policeman’s uniforms until the 1920’s . Despite no longer being used commercially, the subtle variations of colour make woad a much loved natural dye.
Because woad self-seeds, it can now be found growing wild along the stretch of the Leeds-Liverpool canal which passes the Leeds Industrial Museum.
 Dean, J., 2009. Colours From Nature. Tunbridge Wells: Search Pr.
Goodwin, J., 1982. A Dyer's Manual. 2nd ed. London: Pelham Books.
 Goodwin, J., 1982. A Dyer's Manual. 2nd ed. London: Pelham Books.