Rhubarb mordant part 2

I have long last concluded my first test of using rhubarb leaves as mordant instead of chemical ones. (even though they are in fact toxic, they are natural. Or, as MotherOwl points out below, even though they are natural, they are in fact toxic!)

And I have to say, it’s not really worth the effort. Not only does it not help the wool take up the dye any more than an unmordanted skein, in fact sometimes I could hardly see the difference. It also doesn’t add to lightfastness, both of which are the whole point of mordanting in the first place.

I tried both wool and cotton and none had better results than the other for me.


Top to bottom and left to right: Alum + rhubarb simmer not boil, boiled rhubarb + iron, boiled rhubarb, rhubarb + madder, rhubarb + weld, rhubarb + french marigold.

The alum mordanted, rhubarb dyed skein was also a handsome yellow in itself for sure, although it has faded a bit in just a month even without light. Without mordant they are a varying shade of beige depending on how hard you heat the dyebath. The madder is also quite alright, although not any kind of red exactly.

It did have one redeeming feature though: I really liked the shade I got from overdyeing with woad. From historical textiles we can see that some yellows fade away, leaving a once green section of fabric blue, but I’m not really expecting anything I make to live for 600 years. I’ll be forgotten and the line will die out when I do. It’s a patchy dye job because the vat had too little water and too much yarn, so I believe the darkest strands are the “truest” had it been done properly.


Check also under comments in my first post for additional info.


Ikke den helt store gevinst efter min mening, hvilket vi også debatterede under foregående indlæg. Garnet bliver ikke lysægte eller optager farve i samme grad som med alun, de gule farver kan knap nok ses ovenpå selve rabarberfarven som bliver mørk beige hvis man koger den. Det brunlige garn på billedet er krap, og den er vel ok, den grønne er overfarvet med vaid, og blev ret god, bortset fra jeg havde for lidt vand i gryden, så den er lidt skjoldet.


hhock10Remember this jar on the right?

It was eventually done cooking on the stove. 2 days like the other 3 skeins, ph 2, as high as I managed to get it. Pure vinegar with some acetic acid. I measured again when done and it was closer to 1.

I was very excited to see if it would keep its rose tint during the dye process and of course after. Well, here you go:

Dry skein reeking of vinegar
Skein rinsed then dried again.

Unfortunately it seems that rinsing out the vinegar will push it towards purple once it dries. Even if there is actually a bit of vinegar in the 2nd rinse water. OR it could be heat. See, I wanted to wrap up this post and put the yarn close to the stove. The most wet ends turned more purplish than the rest before I noticed and moved it. Sic! So, heat definitely pushes it towards purple. As well as time.

I meant to do another skein in there upping the ph slightly – but I lost steam, didn’t get to mordant more yarn, and, well.

I’m going to re-photograph all the skeins later, as they do seem to change a bit after curing. I also don’t always rinse them until they’ve dried and rested for a bit.

And here they are:

* * *

Dre asked me about pH change during the process. I did not measure at each temperature shift, but the juice in the above photos, which started out at 8 and 2, are now 6 and 1 (or that’s as low as my strip goes). The two jars in the window however have not changed since I made them, they’ve been in temps between 15-20 C.

Just for fun I think I’ll stuff some fleece in the highly acidic jar, then afterwards dip it in the former alkaline jar. Which is now no longer alkaline, where did that ammonia go?!

Fun fact which unfortunately I wasn’t allowed to document: when I hung the pink skein to drip in the shower (white floor), the splash pattern was pink in the middle with a larger ring of drops around it, they were indigo blue! As well as the run off between the tiles, dark, dark blue.

Anyone care to take a guess at what happened there and is it related to the pink/purple issue of the finished skein?