Sunday, January 27, 2013

Natural Dyes - Mordants Part 3

The Maiwa Guide to Natural Dyes
What they are and how to use them

Cotton mordanted with alum.

How To Mordant
Here we give the procedure for mordanting. Once again, the procedure depends on the fibre type.

Always use clean non-reactive vessels: stainless steel, unchipped enamel, glass, or plastic. Iron or copper vessels can also be used but the metal will react with the dyebath. Iron will dull or “sadden” colours. Copper will tend to brighten them.

Mordanting wool, silk or protein fibres
  1. Weigh the fibre dry, then scour.
  2. Measure alum at 15% WOF
  3. Measure cream of tartar at 6% WOF (optional, see cream of tartar, mordants part 1).
  4. Dissolve both the alum and the cream of tartar in very hot water in a non-reactive container.
  5. Add the dissolved chemicals to the dye kettle with enough warm water 45º C (110º F) to cover the fibre when it is added - usually a 30:1 ratio of water to fibre. Stir well.
  6. Add the scoured, wet fibre. Over 30-45 minutes bring the temperature up to 90º C (195ºF) Just under simmer for wool, and 85ºC (185ºF) for silk. Hold for one hour, gently turning the fibre regularly. 
  7. Let cool in the bath for 20 minutes. 
  8. Remove the fibre from the mordant bath. Allow to hang evenly over a non-reactive rod (stainless steel, plastic) until it stops dripping. Rotate the yarn or fabric frequently so the alum is evenly distributed. 
  9. Store the yarn or cloth in a damp white cloth for 24-48 hours. Keep it damp during this entire period if proceeding to dyeing. If you are going to store the fibre longer, then it needs to dry completely and then be stored in a dark place.

Mordanting cotton or cellulose fibres
  1. Weigh the fibre dry, then scour. 
  2. Choose your mordants (see individual dyes for recommendations). For multiple mordant baths tannin must always be done first. Each bath must be completed before starting the next one. 
Cotton after treating with pomegranate.

tannin 
  1. Measure tannin to the recommended WOF for the tannin you are using. Dissolve in hot water. Add to mordanting kettle. Fill the kettle with enough water to fully cover the fibre when added. 
  2. Add scoured, wet fibre. 
  3. Heat to 87 - 93ºC (190 - 200ºF) hold for 45 minutes, gently turning the fibre regularly. 
  4. At this point the fibre may be rinsed and mordanted with alum, or left to steep for 8-24 hours before rinsing (steeping will give deeper colours). 
Aluminum Potassium Sulfate 
  1. Measure alum at 15% WOF. Dissolve in hot water. Add to mordanting kettle. Fill the kettle with enough water to fully cover the fibre when added. 
  2. Add wet fibre (already mordanted with tannin). 
  3. Heat to 87 - 93ºC (190 - 200ºF) hold for 45 minutes, gently turning the fibre regularly. . 
  4. At this point the fibre may be a) rinsed and remordanted, b)rinsed and dyed, or c) left to steep for 8-24 hours before rinsing (steeping will give deeper colours). If you are going to store the fibre then it needs to dry completely and then be stored in a dark place.
Aluminum Acetate 

 For this mordant you do not “cook” the fibre. You begin with very hot tap water 38 - 50ºC (100 - 120 ºF) but do not maintain heat. Because it is not heated, a plastic container may be used for mordanting.
  1. Measure aluminum acetate at 8% WOF, dissolve in hot water, add to mordanting kettle. Or use your homemade aluminum acetate. Top up the kettle with enough hot tap water 38 - 50ºC (100 - 120 ºF) to fully cover the fibre when added. 
  2. Add wet fibre (already mordanted with tannin). 
  3. Let fibre sit for 1 - 2 hours stirring from time to time. Keep the kettle covered so that it retains its heat.
  4. Remove fibre and hang to dry. 5 Chalk(1) (fix) the fibre. Dissolve 50 g of chalk (calcium carbonate) in 5 litres of warm water. Dip fibre into this solution. Fully wet the fibre, wring out and proceed to dyeing. If using wheat bran, mix 100 g of wheat bran in 5 litres of warm water, fully wet the fibre, wring out and proceed to dyeing. These solutions may be maintained over time and occasionally refreshed (after every 10 kg of fibre).
  5. Proceed to dyeing or if you are going to store the fibre then it needs to dry completely and then be stored in a dark place.

*Aluminum acetate must be fixed to the fibre prior to dyeing. In some cultures this is known as “dunging” as cow dung is used. Dung is high in phosphates, but you may also use wheat bran or calcium carbonate (our preferred choice).


 Iron

Iron may be added to the dyepot or it may be done as a separate step after dyeing.
  1. Measure iron at 2% WOF. Dissolve in hot water. Add to mordanting kettle. Fill the kettle with enough water to fully cover the fibre when added. 
  2. Add wet, mordanted fibre 
  3. Heat to 71 - 77ºC (160 - 170ºF) hold for 30 minutes. 
  4. Rinse well. Remember always thoroughly scrub a pot that has been used to iron mordant or it will sadden the next dye bath. Note cellulose fibres can be fully dried and stored before dyeing. Fibres do not need to be remordanted between dyes. Once a fibre has been mordanted it can be dyed and then overdyed without any further mordanting.

Osage on wool. Top at 20% WOF. Bottom with Iron at 2% WOF.




The Maiwa Guide to Natural Dyes



13 comments:

  1. What would you recommend as a mordant for mixed fibres like hemp silk, which is both cellulose and protein?

    ReplyDelete
  2. Hello morgen

    For mixed protein - cellulose fibres, mordant as if they were cellulose with the following cautions:

    1) If the fibre is a wool blend control temperature as for wools to avoid felting.

    2) Understand that the different fibre types will not dye evenly. The protein fibre is very likely to dye heavily and the cellulose lightly. The difference will depend on the exact fibres and the dyes used.

    ReplyDelete
    Replies
    1. Thank-you - I wondered about the uneven color aspect.

      Delete
  3. We received the following question via email:

    QUESTION:

    Other dyer's instructions (particularly Jenny Dean's Wild Color book) call for rinsing well after alum mordanting. Your instructions don't call for any rinsing. What is the difference? I work in a classroom setting with several students putting fiber into the same pot. Which way would be better in this situation?

    ANSWER:


    Thanks for contacting us. We quite like Jenny Dean's book - it has interested so many people in natural dyes.

    In our experience the mordanting step is more effective if the mordant has longer contact with the fibre. You want to achieve two things - thorough contact of the mordant with the fibres and evenness. This is why we encourage a "curing" stage after the mordant bath is complete. You can, of course, rinse fibres after mordanting, but the mordanting step will be less effective.

    We find that if you do alum for an hour and then go onto dyeing a short rinse is good. If you cure alum in the bath overnight then a rinse makes no difference. We lightly rinse after tannin, but generally don't after alum. However, some people feel the alum left in the mordanted fabric effects the pH of the bath - and so when pH needs to be higher rinsing is more important.

    In a class situation, especially if you are pressed for time, rinsing after the mordant would be acceptable, especially if you are working with yarns rather than cloth.

    If students are all putting fibre into the same pot (either for mordanting or for actual dyeing) then there are a couple of key points to remember:

    1) There should be ample room for the fibers in the pot.

    2) Different fibre types should not be put in the same pot together. Some fibres attract the dye or mordant at a much faster rate than others. The effect is that some fibres will come out beautifully dyed while others will show very disappointing results.

    3) Even if using the same fibre type - fibres should all go into the pot at the same time to receive the mordant or dye equally.

    Maiwa

    ReplyDelete
  4. Thank you so much for compiling all of this information. Would it be o.k. if I print this out to offer to students who would like a copy in a workshop? I would not charge for this. It would be a great take home resource. I would, of course, give credit to you, along with your blog/web address.

    Many thanks to you,
    Dawn

    ReplyDelete
    Replies
    1. Hello Dawn,

      Here is a link to our Guide to Natural Dyes as a PDF. It has a creative commons licence - which means we are happy to have it redistributed if it retains the Maiwa name and the notice at the bottom. It has the $1 at the top because we sell the printed version in our store.

      http://www.maiwa.com/pdf/natural_dyeing.pdf

      Delete
  5. Thank you very much for the link and the permission...Much, much appreciated....Such great information.

    ReplyDelete
  6. In your general instructions for mordanting on cellulose fibers, you recommend 8% WOG for the aluminum acetate. But, for the specific dyes, you often recommend 15% for an alum mordant on cellulose fibers. Could you please explain? Is the 15% WOG for alum and 8 % WOG for aluminum acetate?

    Thanks,
    Carmen

    ReplyDelete
  7. If I'm mordanting in successive batches where I'm reusing the same solution, should I add 8% WOG aluminum acetate each time? If I end up having too much aluminum acetate in the solution, is that a problem?

    Thanks!
    Carmen

    ReplyDelete
  8. In the general instructions we are referring to alum (potassium aluminum sulfate) as the mordant and we generally use 15% WOF. We use this mordant for protein fibre and it can definitely be used (with a tannin) for cellulose fibres. However, aluminum acetate is our preferred mordant for cellulose fibres - and we use that at 8%.

    ReplyDelete
  9. Hi All! I am working on my first cellulose dye. I steeped the fibers in tannin for 24 hours, rinsed, and then used alum acetate as a second mordant. Should I let the fibers post alum acetate dry completely before fixing in chalk?

    Thanks!
    Mo

    ReplyDelete
  10. Using vinegar or salt is not effective?

    ReplyDelete
  11. Is there a fix for to much alum mordant on wool? It is very harsh now.

    ReplyDelete

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