Fiber Reactive vs Acid Dyes

Fiber Reactive vs Acid Dyes

I have always used acid dyes for wool and silk because the results are good, the colors are strong and the dye is fairly light and wash fast. Since I need to use fiber reactive dyes for my stitch class, I decided to see if fiber reactive dyes (Procion MX) would work on wool.

In class, while we were dyeing cotton threads, I decided to try some wool thread. With fiber reactive dye, you use soda ash as a fixative. So that’s what I used on the wool thread. The results were very disappointing. The colors didn’t hold at all and the resultant thread was not the color expected at all especially with blue dye.

Ann then suggested that I try using an acid as the fixative with the fiber reactive dyes. So my next trial was wool thread soaked in vinegar water and then dyed. These results were much better. Still not as strong as the acid dyes but the colors held much better, even the blue.

I discussed my findings with Gail Harker (my stitch class instructor) and she questioned whether these results would be light and wash fast. So more experiments to try. I decided to take the thread I had already dyed and put it outside in the sun and rain for a month and see what happened. The photo above shows the results. The threads on the left are the control threads which I did not put outside. The threads on the right were exposed to rain, weather and sunlight for one month. I just attached them to a card and stapled them to my picnic table outside which is in full sun all day.

The top three threads are wool dyed with Procion Mx and vinegar. The second set of three are wool dyed with acid dyes and vinegar. The third set of threads (only two) were wool dyed with Procion MX and soda ash. The last set of threads is cotton dyed with Procion MX and soda ash.

I’m not sure you can see this in the photo but the wool threads dyed with Procion and vinegar faded a moderate amount. The acid dyed wool held very well and had little fading. The wool dyed with Procion and soda ash faded significantly from the color that was already really off from the original dye color. The cotton threads faded slightly.

I also sent an e-mail to the good people at Dharma Trading to see if they had some input about the use of fiber reactive dyes with wool. I learned a lot from Sharon’s (Dharma) response. She said that fiber reactive dyes were originally developed to dye wool fabric in the 1950’s. The manufacturers were disappointed with the results but accidentally discovered how well they dyed plant fibers and happily marketed the fiber reactive dyes for that use.

Sharon also said that the blue fiber reactive dyes do not strike well on wool or silk and tends to come out half strength or less. Therefore, any mixtures with blue dye will have a shift in color for example, purple may come out magenta and black shifts to brown or maroon. Blue is also the slowest dye to strike on cotton or other plant based fibers.

Sharon recommended to treat the fiber reactive dyes just like acid dyes when dying wool Therefore, use acid as your fixative such as vinegar or acetic acid and steam the fiber for 30 minutes to help fix the dyes. She also states that rinsing with higher temperature water will rinse more of the dye out so you will always need to wash/rinse the dyed wool with cool water or dry clean it. She also reports that the fiber reactive dyes will not exhaust like the acid dyes so there will be more fiber reactive dye rinsed out at the end of the dyeing process than with acid dyes.

My next experiment will be with fiber reactive dyes, acid and heat. I’ll see if that helps set the dyes in the wool better than just the acid. The nice thing about fiber reactive dyes is that you don’t have to set the dye with heat in plant fibers. But if I only had to have one type of dye, that would be better so I’ll let you know the results the next time I dye.

I’d love to hear about any experiments you’ve done using fiber reactive dyes and wool and see photos of your results. Feel free to post them on Flickr or join us on the forum and start a discussion about dyeing results.

21 thoughts on “Fiber Reactive vs Acid Dyes

  1. Very interesting – b.t.w. I’m surprised that the colours held on at all after a month outside! I would have expected various shades of grey.

    1. Actually, most of them held their color very well. Just goes to show how well the dye works. Always fun to experiment πŸ™‚

  2. Were the Procion colours that you used on the wool the same both times, or two of them? It worked well with the vinegar. I haven’t tried Procion yet, I bought a yellow and blue recently, but haven’t had chance to read the instructions. I’ve tried acid dyes on bamboo and that gives lovely soft pastel shades. I dyed some cotton fabrics recently, and some cotton top, I’ll post about that, soon. I love the blue and green colours πŸ™‚

    1. The samples were cut from the same thread. So not all colors were dyed the same for the various samples but the control and the tested outdoors samples are the same. Does that make sense at all? I look forward to your post about dyeing.

  3. The best reason not to use fiber reactive dyes with soda ash on wool is that wool can be easily damaged by the higher pH of this method. Plant fibers dye well at high pH, protein fibers at low pH. When fiber reactive dyes are used with vinegar or citric acid instead of soda ash, they become acid dyes. The chemical bond is different.

    You might want to check out Paula Burch’s website, All About Hand Dyeing. Google should help you find it. Paula is a chemist and a dye expert.

    1. Thanks Julie – I really should have mentioned that about the soda ash on protein but forgot to include that in my post. I have checked out Paula’s site but I learn so much better by doing that I just keep experimenting. Thanks for pointing that out! :0)

  4. Sorry, I didn’t explain very well, on the wool samples where you used Procion, did you use the same colour dyes with soda ash as you did with vinegar?

    1. No – I didn’t. Mainly because I did one set in class and then did the other set at home. So I didn’t have the same dye mixtures and I wasn’t really thinking about the whole test thing at that point.

  5. I have used procion dyes with Vinegar. One does not soak the fiber in the acid as it is too much; I mix 1/4 tps of procion dye in a cup with 4 Tbls of water to make a slury then I use just a few tps of Vinegar, wrap in cellophane and nuke it in the microwave for 3 minutes. I Heat is what opens the cell walls in the wool to allow the dye to migrate into the cells. This method works beautifully on silk and wool alike. One time I mixed dye with water and dye thickener used a found object and stamped it onto felt (I forgot the vinegar) so after it was dry I STEAMED the wool vessel with vinegar for 20 minutes, let it cool totally before rinsing. It was totally wash fast.

    1. Thanks Deb. I am definitely going to try it with heat next time. I have stamped on felt with acid dyes but not procion dyes.

  6. my friend made a cushion using procion dyes but didn’t use any soda ash in the mix, how can she now fix it so that she can wash her cushion in the future?

    1. Did she rinse the fabric after dyeing? If so, it should be OK. If she didn’t rinse, I think she will lose a lot of color if she washes it. There isn’t really anything that will help at this point as far as I know. But the best bet would be to check with Dharma Trading or ProChem. They might be able to answer the question.

    2. she is going to spray it with a soda ash but not sure if that will help. thanks for answering.

  7. I just did my first experiments with fiber-reactive dyes this past weekend (I started dyeing with acid dyes in January), so I’m happy to have come across this post. I’m not sure what to make of the results. My instructions said that yarns dyed with FR dyes require “a lot of rinsing”, which was an understatement. I’m finding it a little frustrating that, unlike with acid dyes, there seems to be no way to definitely know that the dye process is actually finished; is this just a matter of experimenting? My instructions just said vaguely that curing time ranges from 4-24 hoursβ€” not terribly helpful, although they also hinted that the longer you let your yarn cure, the deeper the colors would be. I used the same dyes on 3 different yarns: organic cotton, 100% bamboo boucle, and a silk/bamboo blend.

    The silk blend was by far the most troublesomeβ€” I’m still not sure if I will be able to use it, because I’m not confident that the color won’t bleed. Question: If I had simply dyed this blend with acid dyes, would the color bleed from the 49% of the yarn that’s bamboo? I can’t find anything in any of my books that specifically answers this question.

    1. Hi,
      I’m no expert on dyeing and you’ll probably get a better response from Ruth or Ann as I haven’t tried my fibre reactive dyes yet. But I have tried acid dyes on bamboo, I dyed some plain white bamboo tops the same as I did silk-adding the dye directly, wrapping in cling film, and steaming. This is how they turned out using red, yellow and blue dyes
      It’s pale, but nice, so you might get an idea of how the bamboo part of the yarn might look.
      I never had any bleeding or fading either. I hope that helps a little πŸ™‚

    2. Fiber reactive dye always does require a lot of rinsing, much more than acid dye. I usually do three cold rinses to get most of the loose dye particles out. Then I soak the dyed material in hot water with a small amount of Synthropol type detergent. Then I rinse three more times. That usually takes care of any run off. On curing time, I do overnight just to be on the safe side.

      If you dyed the silk/bamboo blend with acid dyes, the silk would have accepted much more color than the bamboo. If you dyed it in a pot and the dye bath water exhausted and became clear, you would not need to do much rinsing at all. That is the beauty of the acid dyes compared to the FR dyes. You would have had variegated colors with the silk being much darker than the bamboo.

      It does take a lot of experimentation to find what method of dyeing you like best. You can find a lot of good information on Paula Burch’s site about many dyeing methods.

  8. I’ve had the same experience with Procion dyes. A lot of rinsing and less vibrant colors than acid dyes. I also like acid dyes because you can mix a color in water, seal it tightly and keep it for a long time as long as it’s stored in a cool place. You can mix, dilute, etc. This eliminates dealing the “powder” very often. I only use Procion on plant based fibers.

    Colormusing you can always overdye the silk if you’re not happy. However, there is usually shrinkage every time you do. Good luck!

  9. Has anyone used citric acid with Procion dyes instead of vinegar or acetic acid?

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