Black Walnut

The black walnut tree is a native tree to eastern North America.  The hull of the black walnut tree is used for dyeing.  It contains juglones and some tannins.  The best, darkest brown is obtained from the fresh green hull of the walnut because, as the husks darken and rot the juglone is damaged and reacts with itself to form an insoluble pigment.  Since the walnut hulls need to be dried for storage and shipping, I collect the green walnuts as they drop from the trees and break off the hulls while still fresh and green and dry them quickly, so hopefully, as much soluble dye components are preserved as possible. 

Black walnut husks can be used to dye directly on protein/wool fibers without the use of a mordant.  Black walnut is one of the few direct dyes (substantive dyes) that do not need a mordant for the dye to bond to protein fibers.   A mordant, such as aluminum acetate, should be used when dyeing cellulose fibers with black walnut because cellulose fibers do not have the same electrical charge as protein/wool fibers. 

Fresh walnut hulls give the strongest color, but dried hulls are easy to store.  When dyeing with dried walnuts, about 20% WOF (weight of fiber) of hulls will give lighter colors, 50% WOF for medium shades and 100% WOF for dark browns.  If a light shade of brown is desired, either use a weaker dye bath or take the fiber out when you have achieved the desired color.  For a darker brown, give plenty of time for the color to be extracted from the hulls and plenty of time in the dye bath for the color to adhere to the fibers.  Walnut is not sensitive to heat, and iron will deepen the color. 

Please note that on regular, non-superwash wool and some cottons and linen, you are likely to only receive a tan color from black walnuts.  Dark brown can be achieved easily on superwash wool yarn and silk.  Superwash wool takes acid or natural dyes more deeply, and so you will get a darker, deeper color if you use superwash wool instead of regular wool.  Black walnut is a substantive dye and does not need a mordant to help it dye fibers, but you will likely get a darker color if you mordant the fiber before dyeing with black walnut.  An iron afterbath can help deepen the color as well.

A good black can be obtained by overdyeing walnut and indigo.

When dyeing cellulose fibers with black walnut, you can skip the tannin bath, since the hulls contain some tannins, but be sure to scour and mordant cellulose fibers properly.