4. BioChromes

Research

Natural pigments are substances that have been used for millennia to impart color to different materials, such as fabrics, paints, foods and cosmetics. Their origin dates back to the first human civilizations, and they were mainly obtained from three main sources: minerals, plants and animals. Here I detail the origin of each type:

1.Minerals: Mineral pigments are derived from natural rocks and minerals. Some of the oldest and best known are:

Ocher: An earthy pigment found in various shades of yellow, red and brown. It is composed mainly of iron oxides, and was one of the first used by humans, as in cave paintings from more than 40,000 years ago. Ultramarine Blue: Originally obtained from lapis lazuli, a gemstone mined in Afghanistan. It was one of the most expensive pigments in ancient times, used in religious works of art. Malachite green and azurite blue: Copper minerals that were used in ancient times, especially in Egypt and Rome.

2.Plants: Plants have been a rich source of pigments due to the natural compounds they produce, such as flavonoids, carotenoids, and anthocyanins. Some examples are:

Indigo: Derived from the Indigofera tinctoria plant and other similar plants. This deep blue pigment was widely used in ancient India, Africa and America. Alizarin (red): Obtained from the root of the madder plant (Rubia tinctorum), used in Egypt, Persia and Greece to dye fabrics. Chlorophyll: Although its main function in plants is photosynthesis, it has also been used as a green pigment in foods and cosmetics.

3.Animals: Although less common, some pigments were extracted from animals. A notable example is:

Tyrian Purple: A pigment obtained from the glands of certain marine mollusks. It was very valuable in ancient times, especially in Phoenicia and the Roman Empire, where it was reserved for royalty and clergy. Cochineal (red): This bright red dye is obtained from an insect, the cochineal (Dactylopius coccus), which grows on cacti. It was widely used in America before European colonization and later exported around the world.

Other Origins: In some cultures, pigments of human origin, such as blood or charcoal derived from burned bones, were also used to obtain dark colors such as black or brown.

Historical Uses: Natural pigments have had cultural and artistic use throughout the world. The first cave paintings, dyed textiles in Egypt, frescoes from Pompeii or illuminated manuscripts in the Middle Ages are historical examples of the use of these pigments.

In Mexico, natural pigments have been an integral part of indigenous cultures and their art since pre-Hispanic times. Mesoamerican people developed a rich color palette using natural elements they obtained from their environment. Here I mention some of the most important pigments that have been used in Mexico:

1.Cochineal/Grana (carmine red) Origin: It comes from the insect Dactylopius coccus, which breeds on nopales (cactus). This insect produces carminic acid, which is transformed into the famous red pigment. Uses: It was used in textiles, paints and cosmetics. During colonial times, cochineal became one of Mexico's most valuable export products. Currently, it continues to be used in textile crafts, especially in Oaxaca fabrics. Colors: The pigment that is extracted can vary between intense red, pink and purple, depending on the treatments given. Many artisan communities in Mexico, especially in Oaxaca and Chiapas, continue to use these natural pigments to dye textiles, make artisanal paints, and produce ceramics. The preservation of this traditional knowledge is fundamental in Mexican culture.

Fig. 1 Cochinilla

2.Indigo/maya blue (indigo) Origin: Indigo, known in Mexico as indigo, comes from the Indigofera suffruticosa plant. Although it was more associated with southern Mesoamerica (mainly in regions of what is now El Salvador and Guatemala), it was also used in Mexico. Uses: Mainly for dyeing textiles. This pigment produces a deep blue, highly valued by pre-Hispanic cultures and Spanish colonizers. Colors: Ranging from light blue to dark blue.

Fig. 2 Indigo

3.Tezontle (red) Origin: Tezontle is a porous volcanic rock that, when pulverized, was used as a pigment. This material is typical of volcanic areas of Mexico, such as the Valley of Mexico. Uses: It was used in architecture and to decorate pre-Hispanic buildings and temples. It was also used in the creation of murals. Colors: Reddish or terracotta tone.

Fig. 3 Tenzontle

4.Ocher (yellow, red and brown) Origin: Ocher is an earthy pigment composed of iron oxides that is found in various shades, such as yellow, red and brown. It was found naturally in several regions of Mexico. Uses: In murals, ceramics and sculptures. It was used by many cultures, including the Mayans, Aztecs and Mixtecs. Colors: Yellow, red, brown and intermediate variations.

Fig. 4 Ocre

5.Ashes and charcoal (black) Origin: Black was obtained from burning different materials such as wood, bones or charcoal. Pulverized wood or bone charcoal was also used. Uses: It was used to decorate ceramics, murals and in rituals. Additionally, black derived from charcoal was used in tattoos and body paint in many Mesoamerican cultures. Colors: Black and gray.

Fig. 5 Charcoal

6.Jamaica (red and purple) Origin: The hibiscus flower (Hibiscus sabdariffa) has been used both in infusions and to obtain pigments. Although it is best known for its use in beverages, a natural red dye is also extracted. Uses: In addition to being used in gastronomy, it is used to dye textiles and in some artisan products. Colors: Dark red and purple.

Fig. 6 Hibiscus

7.Chlorophyll (green) Origin: Chlorophyll is the green pigment found in plants. In Mexico, it was used to extract green color from various leaves and plants. Uses: To dye textiles, in mural painting and in ceramic decorations. Colors: Green.

Fig. 7 Leaves

8.Cempasuchil flower (yellow and orange) Origin: The marigold flower (Tagetes erecta) is a very representative flower of Mexico, especially on the Day of the Dead. A bright yellow pigment is extracted from its petals. Uses: In the creation of dyes and colorants for textiles, in food and in ritual ceremonies. Colors: Yellow and orange.

Fig. 8 Cempasuchil flower

These pigments, in addition to their aesthetic value, had deep cultural and symbolic meanings related to the indigenous worldview.

Activity Description:

1. Color font selection This activity was done in two parts, the research that was done with the fab puebla team and the one that I did personally. As a team we work to do the color extraction using bougainvillea petals, hibiscus, avocado seed, spirulina, turmeric, muitle, annatto and indigo. I worked with the extraction of colors from rose petals that were waste from a flower shop and muicle leaves.

2. Color extraction/modification The pieces of fabric were pretreated with sodium carbonate to eliminate impurities (10% w/v) 30 min, 60 C. Subsequently, the fabrics were placed with the solution of 25 g of aluminum sulfate per 10 g of fabrics and 500 mL at 60 C. 200 g of leaves or petals were used.

Fig. 1 Blanket

Fig. 2 Wool

Fig. 3 Muicle infusion

Fig. 4 Rose petals infusion

Color modification was done by adding 1 ml of a 1% w/v NaOH solution to 50 mL of color solution.

Fig. 5 Muicle basic pH

Fig. 6 Muicle modified pH

Fig. 7 Color comparation with pH modifified

With the group, color extractions and modifications were made with each of the previously mentioned materials. The blanket and wool were dyed.

Fig. 8 Final result: wool, blanket, and pH modification

Fig. 9 Chromatic circle

Results and more

The colors obtained with the muicle and rose petals are very intense, softer colors can also be obtained by making dilutions. The color obtained in the fibers of animal origin (wool) in all cases was always more intense than that obtained in the fibers of plant origin (blanket).

There is a plant in southern Mexico that produces a fruit from which very fine structures can be recovered that can be used for threads, but more research is required. But they were also dyed.

Fig. 1 Pochote tree

Fig. 2 Pochote fiber

Fig. 3 Wool, blanket, and pochote´s fiber dyed with rose petals extraction

There is a technique widely used in India to print fabrics which is "block printing". I did a test on an untreated fabric, just to see if it would work. The wool could not absorb this pigment, but it did in the blanket. Although the pigment runs through the blanket and the result is of low quality, you can make prints on the fabric with this technique and obtain new colors by changing the pH.

Fig. 3 Block printing test

Fig. 4 Block printing with acid on dyed blanket

Fig. 5 Block printing with acid on dyed blanket

Conclusion

In summary, the origin of natural pigments is deeply linked to the resources that different civilizations had at their disposal, and their use has been crucial for both art and science throughout history. It is necessary to expand research on dyes, especially in a country like Mexico. The extraction method can be evaluated: organic solvents, temperature, cold press, etc. The type of pretreatment of the fabrics, the mordant and in each case its concentrations can also be evaluated. In this activity, studies were only carried out on fabrics such as wool, blankets and pochotes fibers. However, the analysis of more fabrics is required as well as the evaluation of these dyes over time and after use and washing. I consider that the treatments that allow maintaining the intensity of the colors should be analyzed.

References & Inspiration

• Blockprinter - [Blockprinter] (https://trayectotextil.com/blockprinting/)
• Blockprinter - [Maiwa] (https://maiwa.com/collections/block-printing)