How to extract blue dye from woad

This is a blog post on how to extract blue dye from woad plants. Once one knows how to extract blue dye from woad you will be able to use for fabric dyeing. Not too long ago I wrote a blog post on how to grow and harvest woad. Woad also is known as Isatis tinctoria is an ancient old blue dye plant. It is not an edible plant but grown for blue dye. The leaves itself don’t produce blue dyes instead it’s a process of seeping the leaves, harvesting it on its first year of growth, and agitating/ whisking it with washing soda that produces a blue dye. Therefore the purpose of this post is to explain and how to achieve that.

How to extract blue dye from woad

First all have some washing soda, separate dye pot that can be heated and a stove on hand. Then harvest the woad leaves. It’s been told in the natural dyeing books the best harvest is during in the morning sometime during summer. This period is sometime end of July and August on the first year of planting woad. Harvest the nice and broad and matured leaves. Don’t worry too much about cutting too much off woad plant will regrow pretty quick.

Collect as much as you can as much as it may seem the actual blue dye extract is not a lot. It is something like a kilo of leaves to 5 grams of dye powder. I have not measured of extracted the powder out of the blue dye I have prepared so I can’t really let you know exactly how much.

Then in a pan bring the water to boil with the leaves in it. The best water to use is rainwater as it contains less chlorine but it doesn’t matter if there isn’t any. Then let it boil for about 10 minutes. There will be a strong smell but that is where the leaves are producing the lovely brown red-wine colour liquid. Take the pot off the heat, cover and let the leaves steep. This so as to extract deeper colours. If you find it is not seeping more colours bring the mixture to boil then turn it off and let it rest again.

When there is the lovely rich brownish deep red color then add washing soda or soda ash. this will create a chemical reaction that will produce the blue dye powder. The liquid will turn into a deep green color. For further steps follow my previous blog post on preparing indigo for dyeing. also above are the fibre that I have dyed with woad solution. It is light in colour as the concentration not as high as indigo and also there is thiourea dioxide added.