4. BioChromes

Research

Image Taken from Chemical dyes Lab at Bahir Dar University, Ethiopian Institute of Textile and Fashion Technology

Natural dye manufacturing involves extracting coloring compounds from renewable plant sources and applying them to textile fibers through eco-friendly processes. To manufacture natural dyes, we will first extract the color from plant materials by simmering them in water for about an hour. The liquid is then strained and used to dye fabric by simmering the damp fabric in the dye bath for another hour. For this week assignment I used turmeric powder, red onion skins, avocado pits, tea bags, and beetroot. For turmeric, we can simply mix the powder with hot water, while for avocado, it’s best to use pits and skins left to soak overnight before simmering. Tea leaves are steeped in hot water, and onion skins are typically simmered for an hour or more. The goal is to achieve lasting, aesthetically appealing colors while minimizing environmental impact.

Process and workflow

I. Extraction of Natural Dyes

The extraction process aims to release the pigment compounds from plant tissues into a liquid medium (usually water). The efficiency of extraction depends on factors such as temperature, time, material to water ratio, and plant type.

1. Preparation of Plant Materials

The first step is to prepare the dye sources to maximize color release: for this assignment I used the following plant materials: • Beetroot: Peel, chop, or blend raw beets to expose the pigment-rich interior (betanin).

• Turmeric: Use either fresh rhizomes or powdered form. When using powder, pre-mix it with hot water to make a smooth paste for even dispersion. I used the powdered turmeric.

• Avocado: Collect pits and skins both fresh and dried can be used. They contain tannins and anthocyanin-like compounds that yield soft pink to peach tones. For this assignment I used the pits one.

• Tea Leaves: Use loose black or green tea leaves (or tea bags) for warm brown tones. Tea bags are used.

• Onion Skins: Collect the dry outer layers of red or yellow onions; these provide golden to brownish shades due to quercetin pigments.

2. Simmering for Pigment Extraction

Transfer the prepared plant material into a non-reactive pot (stainless steel or enamel) and add enough water to submerge it completely. • Bring the mixture to a boil, then reduce it to a gentle simmer. • Simmer for 20 minutes to 1 hour, depending on the material: • Turmeric requires about 20 minutes. • Beetroot, tea leaves, and onion skins need 30–45 minutes.

• Avocado pits and skins can take up to 1 hour or more to release full color.

• During simmering, pigments dissolve into the water, forming a concentrated dye liquor.

3. Straining the Extract

After simmering: • Allow the mixture to cool slightly. • Strain it through a fine cloth or sieve into a clean container. • Discard the plant residue. The filtered liquid is now the natural dye solution ready for textile dyeing.

II. Fabric Dyeing Process

This stage involves transferring the extracted color from the dye bath onto the textile fiber. Proper preparation and controlled conditions ensure even, durable coloration.

1. Fabric Preparation

Before dyeing: • Wash the fabric thoroughly to remove oils, finishes, or impurities. • Pre-wet the fabric with clean water; this allows the dye to penetrate evenly during immersion. Optional: For better dye absorption and colorfastness, fabrics (especially cotton or silk) can be pre-treated with a mordant (e.g., alum, iron, or vinegar) but not used for this assignment. Mordants help bind natural dyes to the fiber structure.

2. Heating the Dye Bath

• Pour the strained dye extract into a clean pot. • Add enough water to allow the fabric to move freely without overcrowding. • Heat the bath until it reaches a gentle boil.

3. Dyeing Process

• Submerge the damp fabric into the hot dye bath. • Simmer gently for about one hour, stirring occasionally to ensure even color distribution. • Monitor the shade: longer simmering or repeated dipping can deepen the color.

4. Cooling and Rinsing

• Remove the fabric from the dye bath and allow it to cool naturally. • Squeeze out excess liquid gently without wringing. • Rinse the fabric in cool water until the water runs clear.

5. Drying and post-treatment

• Hang the fabric in the shade to dry (direct sunlight may fade the colors). • For best results, allow the fabric to rest for at least a week before the first wash. • Wash later using pH-neutral soap and cold water to preserve the dye.

III. Final outputs

RESULTS

Turmeric Avocado Pits Beetroot Tea Bags

Making Avocado Seed Lake Pigment Using Sodium Carbonate and Alum

Avocado seeds contain tannins and polyphenols that produce pink to reddish-brown dyes. When combined with alum and sodium carbonate, these natural colorants can be fixed onto an aluminum hydroxide base to form a stable avocado lake pigment.

Materials

• Avocado seeds (3–4 large seeds)
• Alum
• Sodium carbonate
• Distilled water
• Heat source (stove)
• Jars
• Filter paper or fine cloth
• Stirring rod

Procedure

1. Extract the Natural Dye
   • Wash and peel the avocado seeds to remove the brown outer skin.
   • Chop the seeds into small pieces or grate them.
   • Place the pieces in a pot with 100 mL of water.
   • Simmer gently for 30–45 minutes until the water turns a deep reddish-brown.
   • Strain the liquid to remove solids and keep the dye solution.

1. Prepare Alum Solution
   • Dissolve 10 g of alum in hot distilled water.
   • Stir until fully dissolved.
   • This provides aluminum ions that will bind with the dye.

1. Prepare Sodium Carbonate Solution
   • Dissolve 5 g of sodium carbonate in warm distilled water.
   • Stir until dissolved.
   • This will precipitate aluminum hydroxide when mixed with alum.

1. Combine the Solutions
2. Mix the avocado dye extract with the alum solution while stirring.
3. Slowly add the sodium carbonate solution drop by drop.
4. A colored precipitate will form this is the avocado lake pigment.
5. adding sodium carbonate until no more precipitate forms.

1. Settle and Filter
2. Allow the mixture to stand for several hours or overnight.
3. Filter the mixture using filter paper or a fine cloth.
4. Wash the precipitate several times with distilled water to remove excess salts.
   
5. Dry and Store
6. Spread the washed pigment on a clean surface or tray.
7. Let it dry completely at room temperature or in a warm, dry place.
8. Once dry, grind it gently into a fine powder.
9. Store in an airtight container away from light.

Result

I obtained a soft pink to reddish-brown lake pigment derived from avocado seed dye fixed onto an aluminum hydroxide base. The exact hue depends on the seed maturity, pH, and concentration of alum and sodium carbonate.

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