No mordant?

Alum mordanted yarn hung out to dry, after making a rediscovery in my own stash. There might be some plant dyeing happening around here after all! I was inspired to begin with these. A plant that I’ve tried to get rid of in my horse paddocks, but I’m sure I can find some still. Result report guaranteed  if and when!

I often come upon blogs about plant dyeing, usually beginning dyers, mentioning how they mordant their yarns with vinegar or salt. Don’t get me wrong, I’m not rallying against beginners, like myself!, posting about their passions and experiences. But this being a pet peeve of mine, I’m going to mention it again: Those are NOT “mordants”.

A mordant is something which “opens” up the fiber to soaking up more dye stuff = colour as well as keeping it there, making your yarn more light- and wash fast. Usually it’s a metal salt, alum, iron (which I think works better with alum too); also copper and tin which are quite poisonous and chrome which is actually not available in many countries as it can alter your DNA. Not worth the trouble imho. I have a very small jar of tin salt to get deep, bright reds from madder, that’s it.

Vinegar can in some cases be used as a modifier = alter a colour which is pH sensitive. Mostly it does nothing however, but your wool does love you for not throwing it into an alkaline bath, which will break down the fibers eventually. (so will iron btw)

Salt? Is used in dyeing cellulose fibers with synthetic fiber reactive dyes. In plant dyeing? Hell if I know! And yes, I’ve added salt to a couple of dyes just because, and well. Nothing.

I’ve also dyed a few skeins here and there without alum mordant to get pastels and to compare. Top row are the same bath, with mordant. These skeins have been hidden away in a box, but kept in sunlight, the unmordanted versions also fade more easily than the others. These were just what I could find today, the really pale ones are long gone.


So my recommendation for obtaining pale colours is: short dye baths, low plant to yarn weight ratio or use the dye bath multiple times. But do make the effort of alum mordanting everything. (the exception being woad and indigo dye, which is a completely different story anyways)


10 thoughts on “No mordant?

  1. I second that. All those strange things circulating as “mordanting”. Gratz on finding a hidden treasure (stash).

  2. Good one again, Pia! Yourbadvice works for eco dyeing/printing, too. True, one can get a print often enough without alum as mordant- but will it last? Thanks for bringing this subject up.

    1. I’ve been very curious about the whole soy milk, sea water etc. thing but having only tried it on cotton which is imho more difficult to dye than protein fibers in any case, I haven’t yet found it to be effective.

  3. Very interesting. Wow, I actually did not know what a mordant was – I kinda guessed it was a “fixative” i.e. it stops the dye running out again next time it gets in water. I’ve never dyed anything the natural way (I think once I dyed fabric when I was a teenager, the dye came from the store) so am clueless about the methods. Probably never will dye anything, but I’m happy that I know more about it now!

    1. I have great fun reading about crafts other than my own – just have to keep resisting the urge to want to try all the things myself. Just relax and enjoy watching/admiring.

  4. Having had an enforced period of unpluggedment (that is so a word!) courtesy of a broken laptop I’m only just reading this post and wondering if you can hear me cheering from afar! It really bugs me how often lately I see glossy posts on natural dyeing written by beginners who really don’t have a clue. I’m not knocking their sharing their journey to understanding but I have studied and practised plant dyeing on and off for 30 years and seem to be far more humble about what I know precisely because I’ve grasped how much I don’t. It’s an easy entry craft but mastering it is a whole other ball game. Salt as mordant on naturally dyed wool and what are stains being described as dyes are two of my biggest bugbears. I’m all for an eco friendly approach and don’t bother too much about colours fading because even with alum so many are quite fugitive, but then I take care about what I knit up with what. Those of us who know better need to speak out I think before the myths being perpetuated by the fly by night crafters – who will have moved on to the next website traffic generating fad they know little about by next week – spread too far. Sorry, mini rant over, can you tell I feel strongly about this!

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