Eastern Redbud Natural Dye Experiment

The eastern redbud trees near my home bloom every spring and are so beautiful with their branches covered in purple/pink! The branches are covered in thousands of tiny little flowers:

I am going a bit crazy with dyeing things and wanted to see if these flowers would make a lasting dye (I picked my flowers off the ground under the trees because it seemed like a shame to take them off branches). Remember, most plants won't work for dyeing (either the color won't stick to fabric, or it will fade quickly, or something of the sort). This was an exploratory experiment!! If you want to try this or any similar experiments on your own, remember to use separate utensils/pots for dyeing and food, ventilate well, and don't trespass or take stuff that isn't yours when collecting dyestuffs.

For all tests below, I tested bits of wool (Lion Brand Fisherman's Wool, in Natural) and cotton (Bernat Handicrafter Cotton, in White). As usual, nothing fancy.

Experiment 1 - vinegar, moderate heat, no mordant, wool and cotton
Dye extraction: Pour 3 handfuls of flowers into a glass jar that can withstand boiling water. A teacup also works. Boil water and pour into jar/cup, enough to cover flowers. Insulate (e.g. in a cooler or insulated bag) overnight or up to 48 hours. Strain out flower pieces. Mine were a soggy gray/brown color when I took them out, so it looked like most of the pink color had transferred to the dye bath.

Dyeing: Add yarn to be dyed into the dye bath jar. I let the jar sit for about 24 hours on a windowsill. I noticed the dye bath got more colorless, and the cotton yarn turned a beautiful medium pink. The wool yarn looked pretty unchanged... so I added a splash of vinegar. The vinegar immediately brightened up the dye bath to almost hot pink. Then I boiled some more water, filled 2 separate jars with the hot water, and put it all in an insulated bag overnight so the hot water bottles would gently warm up the dyebath. I let this sit for a weekend (obviously it wasn't hot anymore after the first few hours) and then rinsed out the yarn.

Results: The cotton was a beautiful pink before rinsing (unfortunately had my hands full so didn't take a picture at this stage), but most of the pink rinsed out leaving a pale gray-ish lavender. It's subtle, but I like it. In hindsight, I wasn't sure whether the vinegar addition changed the cotton, so tested without vinegar in round 2 (below). I'll be washing this sample a few more times to see if it sticks. The wool didn't do much, maybe got a bit dingier or dirtier looking.

Top: Undyed wool sample in skein with the dyed (basically unchanged) small sample on top
Bottom: Undyed cotton in skein with dyed (lavender) small sample on top

Experiment 2 - salt, moderate heat, alum mordant, wool and cotton
Pre-mordanting: Soak yarn for a few hours in a glass jar that can withstand boiling water. I poured off most of the water and replaced it with boiling water (pouring along the sides of the jar and not directly onto the wool to avoid felting). Then I poured in alum (wear a mask! make sure you have ventilation! alum can be irritating) and gently swirled the jar to dissolve. I placed this in my insulated bag from round 1 with another jar of hot water and let it sit overnight (while simultaneously extracting the dye).

Dye extraction: Same as round 1, extracted for about 20 hours. I used a different jar and cozied the extracting dye jar up to the mordant solution jar in the insulated bag.

Dyeing: Move the yarn directly from the mordant solution into the dye bath. I boiled some more water, filled 2 more jars with hot water, and put it all in the insulated bag for 48 hours, replacing the hot water every 12 hours or so.

Results: The cotton was again a beautiful pink before rinsing, and washed out to a grayish-purple, but this time slightly darker than in experiment 1. In the picture below, I washed only half the sample so you can see both the washed and unwashed colors.

Left: results from experiment 2. Unwashed portion is at top (more pink) and washed portion is at bottom (more light purple).
Right: results from experiment 1, for reference.
Back: undyed white cotton skein, for reference.

When I later washed out the pinker area (previously unwashed), most of the pink came out and it was a (very very) slightly darker version of the washed section (bottom left portion of the experiment 2 picture above).

The wool didn't do much (no picture of this, because I immediately tossed it into experiment 3).

Experiment 3 - stovetop heat, acid and salt, wool and cotton
As a final test, I used the wool from experiment 2 (previously treated with alum) and the cotton from experiment 1 (no alum), dumped the dyebath from experiment 2 into my dyeing pot with a splash of lemon juice and salt, and heated it to a simmer for 30 minutes.

Results: No changes!

Conclusions
Eastern Redbud flowers don't give the most vibrant dye, but they do dye cotton (which is notoriously difficult for most natural dyes) to a cool lavender. Alum helps deepen the color a bit. Wool doesn't seem to work with this dye.

Also, if you're looking to naturally dye something pink that won't be washed (e.g. a macrame wall hanging or plant hanger), then this could be an option. Bonus points since Eastern Redbud flowers are supposedly edible (but I can't verify this) and alum is an irritant but not poisonous, so the dye is relatively non-toxic.

Here is a picture of the cotton from experiment 2 after about a week of direct sun exposure (to test fading). I didn't plan ahead so I didn't keep half of the sample out of the sun, so there's nothing to compare to. I think it faded a little bit, but it's still clearly different from the undyed white color.

Future Directions - unanswered questions that I might explore in the future

• What if I use more flowers for a smaller amount of yarn?
• It seems that most of the pink color in the dyebath isn't a true dye, but there is a more subtle purple color that does dye the cotton. The purple is only at the bottoms of the flowers (and you can see it more clearly when the flowers dry out), so there's not much of it to work with. Would I get a darker color using twice the number of flowers? I didn't weigh anything in these experiments, but would be worth considering for future.
• Does this work with frozen flowers?
• How long does this dye last? (How many months or how many washes?)
• Does simmering on stovetop help with dye extraction? Development of color? Dye fastness?
• Do other mordants give darker/richer color? E.g. commonly-used cotton mordants like aluminum acetate or alum-tannin?