Dye Project: Bolete with Ferrous Sulfate

For my third mushroom dyeing project, I again decided to use the Boletus edulis that had popped up under the oak tree in our yard after fall and winter rains, and to recycle another cotton dish towel from my stash. The dish towel had been mordanted with alum, and I planned to use ferrous sulfate (iron) as a mordant additive for this dye experiment.

A Boletus edulis under the oak tree

Greenish-yellow mushroom underside

The dye color for B. edulis comes from the mushroom cap underside, which is very spongy. I separated the spongy underside to harvest the dye material. The color is greenish-yellow.

Extract the Dye

For this project, I had previously extracted the mushroom dye, and divided it for three different projects (with the plan to use alum, titanium oxalate, and ferrous sulfate as three separate mordant additives). For information about extracting the dye, see Dye Project: Bolete with Alum, the "Extract the Dye" section. Note that a film of mold had started to grow on the surface of the dye liquid, but I just skimmed it off. The pH of the liquid still registered 3 (moderately acid).

Dye the Fabric

Dye the fabric with the mushroom dye liquid. For this experiment, I recycled a cotton dish towel that had been mordanted with alum and then dyed with the second extract of logwood with an iron mordant additive, which had produced a pale gray [see Dye Project: Logwood Exhaust 2 (Alum + Iron)]. I used the remaining third of the dye and added ferrous sulfate as a mordant additive.

Ferrous sulfate (or iron) is known for "saddening" or darkening the dye. It produces a deeper tonal range or gives a gray/brown cast to a color. More on ferrous sulfate.

Boletus dye pot with ferrous sulfate additive

Place the extracted mushroom dye in a dye pot and stir in a pinch (about 1/4 teaspoon) of ferrous sulfate as an additive. I tested the pH of the liquid, which still registered 3. Meanwhile, place the dish towel in clear water to soak for 20-30 minutes, to enable the fibers to soak up the dye.

Heat the mushroom dye to 185 °F (this takes about an hour to reach the temperature). Squeeze out the wet towel, and place it in the dye. Simmer for one hour, maintaining the temperature at 185°. Add water periodically to keep the fabric covered with dye extract.

Steep the cotton fabric overnight

Turn off the heat and steep the fabric overnight. The next day, squeeze out excess dye, rinse the fabric, and then run it through the washing machine (cold water only), and hang to dry.

Full disclosure: I wasn't thinking, and actually added a mild textile soap [like Synthropol or Professional Textile Detergent (a.k.a., Dharma Dyer's Detergent)] to the rinse, and then dried the towel in the dryer (I usually just rinse and hang to dry, and then wash in mild detergent two weeks later, giving the dye time to set). It seemed to work OK, but was not my usual process.

Squeeze out excess dye and rinse thoroughly

The resulting color was a pale gray when wet (although slightly darker than the original), but it dried to a lighter shade. The photo really doesn't capture the actual color. Once again I wondered if the mushroom dye actually dyed the fabric at all, or did it simply cause a slight over-dye reaction with the previous Logwood extract dye?

The resulting color is pale gray (although slightly darker)

In summary, these three experiments using Boletus mushrooms have been interesting. I can't really tell if any actual dyeing happened, or were the original colors simply changed or intensified by the mordant additives (alum, titanium oxalate, and ferrous sulfate). So far I have to concur with the literature that mushroom dyes do not work as well with cotton fiber as protein fiber. For future mushroom dyeing projects, I plan to use protein fibers (silk and wool), which are known to respond well to mushroom dyes and are typically color and light fast. For the previous Boletus projects see: Dye Project: Bolete with Alum and Dye Project: Bolete with Titanium Oxalate.