4. BioChromes¶

Research¶

This week we explore how to obtain colour from nature, studying how different molecules interact with with textile fibres. We learned the methods for preparing the textile, and even preparing and modifying the dye.

Colour has always been an extension of the body: a chemical language hidden in flowers, roots and spices. Natural dyeing is a collaboration: the fibers absorbe that which the living matter releases. And the most interesting part is that the result is not perfect nor fixed, it breathes, evolves and changes with time, as any organism.

Inspiration¶

Fortunately for me, México is a very colourful place, and it has a long tradition of extracting bright and saturated colours from nature.

For example we have Grana cochinilla (Dactylopius coccus) which is a parasitic insect that infects a particular edible cacti called nopal. This insect is sun dried and then powdered using an ancestral traditional grinder made from volcanic rock called metate. It provides a very recognizable deep red colour, and depending on its concentration and Ph, it is possible to have yellowish colours.

I also had the fortune to visit the Jacobo and María Ángeles alebrije workshop in Oaxaca, where they explained how to get some of the brightest colour pigments from combinations of lime stone and pommegranate, different kinds of wood, ash and how to extract some tannins from the bark of some trees. Most of the pigments they use nowadays are sinthetic, but they still share the ancient knowledge through courses and tours.

Pigment extraction¶

BioDyeing is the process of colouring textile fibers with pigments from natural origin, most of the time vegetable, fungi or microbe extracts, combined with ecological techniques that avoid toxic chemicals. How can we get this pigments?

Well the basic theory is to grab something colorful, like petals for example, then dry it, you could use a dehydrator machine for more replicable results, but the sun will do just fine. Having this dried materials, and voilá, for the dyeing process go further on the page.

Let's start from the beginning, we have to find colorful natural materials, i will be using rose petals, which give a purple-violet colour on the fabric.

We could air dry the petals, but because it is a slow process, the petals get oxidized and the colour becomes opaque. In order to preserve most of the colorful properties from the petals, we can use both a convection oven, or a dehydration machine. * The Convection oven process should be around 50°C (122°F) for 2-4 hours. * Using the dehydration machine the parameters should be around 35°-40°C (95°-104°F) for 8-10 hours.

The drying process turned the redish petals into a purple-ish mixture.

After having the petals dried, we used a blender in the softest setting so we got small pieces, but not powder. This coarse mixture will be used for dyeing on the next steps.

Just for a test we added linseed oil to try to recreate some kind of ink or oil paint. Not the best result but it was interesting. Next time we could extract the ink from the residual dye baths through filtering or boiling.

Dyeing¶

Dyeing means to fuse the colour on the fabric, in this case, for such process we use these techniques:

Washing: The process of washing the fibers removes oils, waxes, and impurities from the material.
Mordanting: This is the process for preparing the fibers so the pigment adheres better, somewhat like chemical bond.
PH Modification: With different compounds it is possible to change the PH of the pigments, changing the colours.

So that is how we did it.

Washing¶

We wash the textile patches with neutral soap to remove all the impurities and natural oils. It is also recommended, in order for the dye to remain longer, to use some natural tannins, like avocado skin, grape seeds and skins, or even black tea leaves. In this case we didn't do it as it was later recommended.

Mordanting¶

This process is easy but long and tedious, first we boil water and add alum stone, a semi transparent mineral, until it is disolved in the water, with a ratio of 15%-20% of the weight of the wool, and around 15% of the weight of the natural fibers like cotton or linen.
In this case the Wool weighted 152g, and the concentration of alum was 3.2g disolved on 1l of water. Also the linen cloth weighted 60.8g, and the alum concentration was 1.2g on 1l of water.
After everything is disolved, we soak the textiles for 1 hour in the low-simmering mixture.
After this is done, we squeeze out the liquid and let to cool down to room temperature.

Dyeing¶

In this process I prepared 3 different mixtures for each colour, one with lowered Ph, one without change, and the other with higher Ph. How is the PH difference accomplished? We use clorhidric acid for the lower Ph, and Sodium Sulfate for the higher Ph.
I used two natural pigments, for the yellow colours turmeric powder.
The acidic turmeric mixture was a bit orange, the alkaline mixture ended up being more saturated and earthy, the natural one was a middle point between these two.

The purple-ish colours were accomplished with dried rose petals, and the same procedure was done.
The acidic mixture was very red and the alkaline was blue-ish in tone, the natural one was more pink in general.

During the whole process for both dyes, the Ph was measured using Ph measuring strips that change colour deppending on the Ph of the liquid they absorbe. These twelve samples were donated to the bio-dyeing collection of the FabLab for further reference.