My post about 'How to mordant Linen and Cotton successfully' talks about a 2step process, explaining how to mordant natural plant fibres by using Tannin and an Alum/Soda Ash combination.
The drawback in the above recipe is, that the natural tannin colour will stain the fabric after the first mordanting step. I generally don't mind, but if you are after delicate pinks and your cloth is stained a buttery yellow - well, that might not work!
First, not all tannins stain badly. Always aim for the gallic tannins, like Tara or Oak Gall for the least stained results. Myrobalan or Pomegranate, though also gallic tannins, will, on the other hand, definitely leave behind colour.
This beautiful dress by Nadarra Studio has been dyed with Pomegranate peels only. You can see it will leave a beautiful buttery yellow behind.
My go to plant fibre mordant is always the two step process, but it can be replaced by creating your own Aluminum acetate. As you most likely know, you can buy Acetate in some craft/fibre stores, but it is expensive, has a very short shelf life and only comes in powder form. None of these qualities work for me!
I like to be able to make my mordant on the spot when I need it, inexpensive and no health hazard. To create your Aluminum Acetate mordant three ingredients are required.
Alum,
Sodium acetate and
Chalk.
You will be delighted to hear, that this is also a 2 step process, if a little faster and less hassle. No, I am sorry to disappoint, but simple doesn't go with Natural Dyeing - ever.
You first create your acetate by combining Alum with Sodium acetate. No need for calculations and no need for a big pot to float your fabric in, either. This mordant is very powerful and only needs a quick 3-5 minute soak with constant kneading and moving in a small pot to keep the acetate as concentrated as possible. Followed by drying on the washing line or your dryer on medium heat. (No rinsing!)
Once your fabric is dry you can move onto the second step. As with all plant fibres, there is no affinity to Alum, unless it is bonded with tannin and locking the tannin into the fabric, or, like here, being locked in by chalk. This process was called Dunging in the past and literally is what you are thinking. Cow manure provided the dyer with many phosphates and enzymes and was used to neutralize and fix mordants in the fabric. Nowadays we use Chalk (Calcium carbonate) for fixing mordants and a combination of Wheat bran and chalk to neutralize Mordants. However the name stuck and it is still called dunging today.
Recipe for a concentrated Alum acetate bath
Ingredients Mordant:
Alum 120g
Sodium Acetate 100g
Warm tap water enough to make 1L
Ingredients Dunging Solution:
10g Chalk (Calcium carbonate/L of hot water)
Mordanting steps
- Mix only enough mordant solution to immerse the textile. The fabric does not have to float freely.
- While wearing rubber gloves, immerse the prewetted textile for 3-5min until thoroughly wetted through.
- Remove and squeeze mordant back into the container, for the next piece.
- Without rinsing, dry the fabric on the line or dryer on medium heat.
Dunging Steps
- Dung the dried textile in a solution of Chalk until fully wetted through, to set the concentrated Alum mordant. (If you skip this step, your Alum mordant will not be fixed to the fibre properly and wash off over time)
- Rinse well in clear water.
- Any leftover Alum mordant can be thickened for print applications with Guar Gum.
Proceed with dyeing or dry and store for later use.
Thank you for reading!
Hi ! Thankyou so much for this information !! I am just wondering what you are referring too in the below statement of using leftover alum for printing? Do you have a post on this?
Thankyou!
Hello Andrea, yes 5kg is about accurate for a medium Linen 145cm wide.
Hello Michelle! Thank you for your comment! Because you are actually making Aluminum acetate, the Alum you add is Alum sulphate – Pottassium Aluminum Sulphate Dodecahydrate.
When you list Alum 120g are you referring to Alum sulfate or Alum acetate?
This alum acetate mixture appears to be extremely strong. How much fabric can be treated with this amount? German recipes say up to 5 kg … Thanks for your reply.
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