Quilting 101 - Mordants & Tannins (Part Two)

Let's go back to basics and discuss hand dyeing your own fabrics. In this three-part Quilting 101 series I'll share everything I've learnt so far and show you my results!

When dyeing our own fabrics, we're looking for bright, long lasting colours. The key to achieving the best results is treating the fabric with a mordant before dyeing or using the natural tannins found in some plant ingredients. 

Today I'm discussing mordants and tannins, and I want to preface this post by saying, there is a lot of conflicting information out there. Some dyers swear that salt, vinegar or soy milk yields perfect results, while other dyers refute this claim and suggest mineral mordants such as alum, iron and copper give the best results.

As with every new thing we learn, experimentation is key, and research is vital. One particular video I watched showed a range of options including using soy milk as a mordant, but her results were inconclusive due to the fabric being water damaged prior to dyeing. Although she assured us it works, I saw no result!

Experimentation is required but I'll share the information I found useful, and all the conflicting information, so you can make an informed choice - please do some extra research on the mordant you decide to use.

{photo from Apple Oak Fibre Works}

What is a Mordant?

The word mordant derives from the French word "to bite".  

It's a binding agent that helps natural dyes adhere (or bite) to fabric fibres, resulting in long lasting colours and vibrant hues. A plant may yield a beautiful coloured dye, but this will fade over time without the use of a mordant.

Mordants are mineral based, most commonly alum, iron and copper. They can influence the shade and vibrancy of your hand dyed fabrics producing even more variations in colour.

Because we want to use, wash and enjoy our quilts, protecting the colour from fading or abrasion is key, and a mordant will help keep the colour strong.

What is Tannin?

Tannins are an extra gift from Mother Nature and can be found in most plants, but some plants are richer in tannin than others making them perfect for hand dyed fabrics without the use of a mordant.

They act the same way as mordants, but it was interesting to learn that the tannin level in some fruit/plants decreases as they ripen or age. 

Onion skins, avocado, black tea, walnut, sumac and pomegranate are wonderful natural ingredients high in tannin, that do not require a mordant and are perfect for beginner dyers.

I wasn't sure whether dyeing my own fabrics was an itch I needed to scratch or something I wanted to delve headfirst into, so in Part Three of this Quilting 101 series, I'll share my results, thoughts and my project using fabric that I dyed using onion skins. It was super easy, super gratifying and it didn't require a mordant making it a great place to start.

Are Mordants Toxic?

Working with natural dye is safe and better for the environment, but are mordants toxic? 

Mordants that are dissolved metal oxides like chrome and tin, are toxic and not recommended for hand dyeing fabrics.

Natural fabric dyers prefer to use alum and iron as mordants and used correctly they are the safest. That being said, always protect yourself with rubber gloves, a face mask and apron and only use the products in a well-ventilated area or outdoors. Do not use your tools for any other purpose but mordants and dyeing.

It is a chemical process so treat it as such and protect yourself.

{photos from George Weil}

Types of Mordants

Let's take a look at the three most commonly used mordants:

Alum (Aluminum Potassium Sulphate)

Alum is easy to use, easy to find, the most inexpensive and less toxic mordant available, and it's the most popular with hand dyers. 

From my research, the majority of hand dyers prefer this option because the results are long lasting, the colours are intense and very little of the product is required. 

A mordant bath is created by dissolving the alum in hot water and then the fabric is added, and you leave it to do its own thing - no fuss or bother! Cream of tartar can also be added to ensure brightness of colour.

Recipe for Alum Mordant: weigh fabric and add 10% alum and 8% cream of tartar.

Iron (Ferrous Sulphate)

Iron is preferred by hand dyers for darkening the colour of their dyes. It can be used to mordant the fabric first, but generally its added after the dye bath to modify the colour.

You can take blue to navy or indigo to black using an iron mordant. It expands your colour palette, but it can also damage the fibres of your fabric, so be careful.

Interesting fact, you can also use iron powder from vitamins. Just sprinkle a small amount into your dye bath to intensify the colour.

Recipe for Iron Mordant: weigh fabric and add 5% iron.

Copper (Copper Sulphate)

Copper mordant is slightly poisonous and it must be handled carefully. It does create vibrant blues and greens, particularly turquoise and deep olive, but it's not suitable to use with red dyes.

This one was the least popular with hand dyers, but experienced and confident dyers do create some amazing colour. Use this mordant with extreme caution.

Recipe for Copper Mordant: weigh fabric and add 2% copper and 4% vinegar

Other Mordants

Tin & Chrome

Tin is referred to as mildly poisonous and chrome as highly toxic. Neither of these mordants were recommended by the hand dyers I researched, and I believe are not readily available.

Tara Powder (Tannin)

Tara powder is the most common source of tannin, and it works well with plant-based fabrics as a mordant.  

Recipe for Tannin Mordant: weigh fabric and add 10% of Tara powder to a nylon stocking, then add it to a pot of hot water.

Vinegar or Salt:

This is where information begins to become conflicting. Some dyers swear that using vinegar or salt acts as a mordant where others refute these claims.

The general consensus however was that vinegar is a mild mordant but unreliable. If you're looking for long-lasting results, then it's widely suggested you use alum or iron sulphate.

Soy Milk:

Soy milk is more of a binder than a mordant, yet some dyers swear by it.

I watched the process and even though the results were contaminated, it appeared laborious and not a process I was prepared to try. It's essentially coating the fabric multiple times in the soy milk, building up layers that absorb the dye.

Recipe for Soy Milk Mordant: add 500ml soy milk to 2.5 litres of water and soak fabric for 24 hours. Spin and dry in a shaded spot. Dip fabric back into soy mix for 2-3 minutes, spin and dry in a shaded spot (repeat this last step four times).

Urine:

Yes urine! Specifically stale urine or more precisely the ammonia. It's an old practice and I read that chamber pots were collected for the purpose of mordanting fabrics.

I'll let you do your own research on this one ;)

Can I make my own mordants?

Absolutely! 

To make an alum mordant simply add aluminum foil to a mason jar of water, screw on the lid and leave it soaking until a gel forms. Remove as much gel as required.

To make an iron mordant, soak a handful of rusty nails, bolts or screws in a mason jar with 1 cup of vinegar and 2 cups of water. Loosely screw on the lid and let it sit for 2 weeks where it will turn a rusty orange colour.

As you use the iron mordant, simply add more vinegar and water at a 2:1 ratio to refill the jar.

You can make your own copper mordant by following the same steps as the iron mordant except using copper wire, pennies, pipe etc. - use with extreme caution.

How much water for a mordant bath?

This was another area where I found a lot of conflicting information, but it appears that as long as the fabric is fully immerged in the mordant bath, then you're good. 

I saw one dyer add more water to a mordant bath that was pre-used, to prepare it for another soaking, so I don't think it weakens with too much water. I also saw another dyer top up her mordant as it was processing, and she assured her viewers this was fine.

There wasn't a definite formula for me to share with you, but I guess this would also need to be modified due to the weight or size of the fabric - check the label of your mordant.

If any dyers can add some insight, please leave a comment and share your wisdom.

Things to remember:

• Mordants must be treated as a chemical process, so safety first! Always!

• Fabric must be scoured prior to using a mordant - see Part One!

• Mordants will modify colours depending on the type of mordant used and whether it is added as a pre-mordant, during the dye process or after dyeing.

• If you're a beginner, then opt for the natural tannins in onion skins, avocado, sumac, black tea and pomegranate. You can experiment and see if fabric dyeing is for you without the use of mordants.

• Be willing to experiment and see what works best for you.

So that's everything I learnt about mordants and tannins. 

Next Wednesday we'll look at how to make your natural fabric dye and dye some fabric. I'll also share this month's mini quilt Diana in some hand dyed fabrics, and I'll give you my conclusions on the whole process.

I hope these posts are inspiring you to give hand dyeing a try - all of this information might sound daunting but there's so much fun to be had and colour to be created by experimenting with something new.

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Happy quilting :)