Fading / Lightfastness

One question I’m often asked is how much fading do you get with natural dyes? It’s a good and important question and I want to be able to give an answer that is backed by some evidence; evidence that I can show you.


Whenever I dye new colours, different combinations of dye materials or new yarn bases I like to set up a fade test. This is just a homemade test, it doesn’t provide quantitative results but gives me a visual indication of what to expect.


I wind a sample of each yarn/colour I want to test around a piece of cardboard, and record the set up date, yarn base and dye material, and the light side and dark side marked. I cover half the card (the dark side) with 2 layers of dark paper and secure in place. I then take a photograph and place it in a sunny spot and leave it exposed for a month/4 weeks.

Test cards

Test cards 1 & 2 ready for fade test

I usually shift it around to catch the sun as I want to see the “worst case” fade risk. I might then leave it longer to see how it progresses, but the 4-week test is the standard part.


At the end of a month, I take another photograph, and document details. In this way I can check the repeatability of observations. (And in case you’re wondering if all this sounds a little persnickety ?…. yes I am an ex-medical laboratory scientist; this analytical approach to natural dyeing gives me a buzz, and I love that natural dyeing is the intersection of my long time passion for wool crafts and my professional career.)



While all dyes, natural and man-made chemical dyes do fade in time as the materials they have coloured (fabric, leather, wool etc) are exposed to sunlight, some dyes fade more quickly than others.

The observations I’ve made so far reflect the information kindly shared with me by expert dyer Doe Arnot from Oamaru, and also that which I’ve found published in books and on internet by established, reputable dyers. (I can recommend the Art & Science of Natural Dyes by Joy Boutrup and Catherine Ellis.)

img_5770You can see in the photos that the yellow dyes from plants such as onion skins, marigolds, coreopsis and goldenrod do fade more than other colours such as the pink of cochineal.

The fading effect is not all bad however. It depends on what you want to knit, and having this information allows informed knitting choices.  For example if you are going to knit a cover to protect your car dashboard then most of the yellow dyes are going to fade sooner, but if you’re making a hot water bottle cover that won’t see harsh sunshine, and barely the light of day, then onion skin dyed wool will be ok.  The onion skin dye on this hot water bottle cover has faded slightly to a softer yellow – I dyed this wool (both the yellow and the grey) in June 2018 and knitted the cover in April 2019.  The grey was made with black bean jus, modified with iron and is also still a nice grey colour.

Fade tests also help me to continue improving my mahi; I can see which plants give better results, which combinations result in improved lightfastness – and I especially enjoy investigating and understanding the scientific basis for such results. I always use an Alum mordant (Potassium Aluminium Sulphate), it’s non-toxic and improves lightfastness across the board.

Lightfastness is an important consideration when planning a project with natural dyes, well with any dyes in fact. If you are going to knit, crochet or weave something that you want to last a long time, then you want to know that you are giving your project the best chance of being admired for years.







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