On Leena Riihela’s blog there is a post with some useful comments about some Finnish sources of information about chickweed and some suggestions as to how the misleading notion that chickweed could be used as a mordant might have come about. The post is written in Finnish but there is an English translation underneath. Some of the comments on Leena’s post are also interesting.
If you click on the link to “Riihivilla” on the right hand side of my blog, you will find a link there to Leena’s blog.
Also, in a German dyeing book, “Farben aus der Natur” by Gretel Fieler, published in 1981, I have found a reference to a recipe from 1817 in a German dyeing book by Johann Hinrich Ehlers, in which he mentions the use of chickweed plus alum as a mordant used with logwood for dyeing shades of blue. However, although chickweed is mentioned in the mordanting paragraph, alum is added to the chickweed solution before the wool is mordanted, so it is the alum which is the true mordant here, not the chickweed. I think it is possible that the chickweed may have been used for its potash content, which could shift the colour from the logwood from purple towards blue. It is interesting to find such an old recipe, which is almost identical to those mentioned in the more recent books from so long ago.
Now I must find the time to try out this recipe with chickweed, alum and logwood, to see how it compares with the colours from logwood when chickweed is not included. But before I do anything else, I must continue working on my new book.