Medieval Dyeing: Blue
There are two sources of natural blue dye: woad and indigo. The woad plant was widely used in Britain right through the medieval period and earlier whereas indigo was a later immigrant to Europe. Both plants produce the same colourant 'indigotin' which makes it impossible to tell by chemical analysis which was used in any particular find. Therefore archaeologists have relied on information about what plants were grown, and on documentary evidence of trade in both dyestuffs to decide whether any specific textile find was dyed with woad or indigo. There is an excellent article about woad in The Thirty Year Journal of Academic Papers published for the SCA's 30 year anniversary.
My first experiment with woad was from plants grown in my own garden. The method used and described below is NOT a medieval method. This gave a nice soft blue - like faded jeans.
- 218gms Woad leaves
- 50 gms wool: one of these skeins had been dyed yellow with marigold
- 1 tsp washing soda
- 50 gms hydrosulphite (dye remover e.g. Run Away)
Make the dye liquor
- Crush the woad leaves, cover with boiling water and steep for a 1/2 hour. Then strain the liquor and squeeze out the leaves.
- Add 1 tsp washing soda and beat vigourously to oxygenate (we used an electric mixer) until all of the liquid has turned blue and then back to yellow.
- Heat liquor to 50 C - it is very important that this temperature is kept evenly and not allowed to increase above 50.
- Sprinkle 1 tsp of hydrosulphite over the still liquor and let sit of 1/2 hour DO NOT STIR (from now on the mix must be kept as still as possible). The hydrosulphite is removing the oxygen from the liqour - when the dyed wool is later exposed to air it will change colour.
Prepare the fibre
- While the liquor is sitting (still at 50 C) add the fibre to be dyed to a pot of bucket of warm water so that it is thoroughly wetted.
- It is not necessary to mordant fibre to be dyed with woad or indigo
Dye the wool
- Once the liquor is ready squeeze the excess water out of the fibre and gently add to the liqour - minimising any agitation of the liqour
- Keeping the temperature at 50 C - leave the fibre in the pot for 1/2 hour
- Remove the fibre minimising agitation of the liqour
- Squeeze excess liqour into a holding pot (NOT the dye pot) and rest the fibre in the air for 5 - 15 minutes. The colour will develop over this time but help it along by teaseng the fibre open so that it is all exposed to the air as this is what causes the colour change.
- You can continue to dip and remove the fibre until the depth of colour desired is acheived or the dye bath is exhausted.
- If necessary repeat the final stage of perparing the liqor by sprinkling more hydrosulphite on top of the bath and leaving it 1/2 hour.
Indigo is an eastern plant which came into Europe in a big way in the later medieval and early renaissance period. The following method of dyeing is again not the period method - it uses indigo blocks purchased from a local craft shop and is similar to the woad recipe.
- 185 gms wool + an extra skein dyed yellow with marigold
- 42 gm block of indigo
- 100 gms washing soda
- 50 gms hydrosulphite (dye remover such as Run Away)
Prepare the dye liquor
- Break up the block of indigo and pulverise finely
- Blend indigo with small amount of warm water and mix to a smooth paste
- Blend 100 g washing soda with small amount of water and mix to smooth paste
- Add two pastes together
- Warm large pot of water to 50 C (as above - it will have to be held at this temperature for the entire process)
- Add the dye / soda mix and stir well
- Sprinkle 50 gms hydrosulphite over the still dye liquor and allow to sit for 30 minutes so that the liquor is fully de-oxygenated
Dyeing the fibre
- Make sure that the fibre is thoroughly wetted in warm water.
- Add the fibre to the dye liquor - try to avoid agitating it at all. All the fibre needs to well under the the liquor surface
- Leave in the 50 C dye liquor for 15 - 30 minutes
- Remove carefully, trying not to agitate the liquor. Squeeze out excess liquor into a waiting pot (NOT the dye pot)
- Allow the fibre to air for 5 - 15 minutes and tease it a bit to improve even contact with the air. As with woad it is the exposure to the air that causes the fibre to change colour
- You can repeat this process to get a darker colour - although even our first dip gave a strong royal blue
- Rinse the fibre a couple of times and then once with 1/2 Cup white vinegar with the water
- Finally wash in warm water and rinse and allow to dry