Have you ever wondered where the colors of colorful murals, gorgeous textiles, and even the cosmetics we use in daily life come from? One of the answers is pigments. Throughout the long history, humans have always been curious about colors and have been exploring the production methods of various pigments. Among them, organic pigments are favored because of their natural and environmentally friendly characteristics.
Organic pigments refer to pigments extracted or synthesized from nature with organic compounds as the main components. They are rich and delicate in color, with unique texture and luster. Compared with artificially synthesized inorganic pigments, organic pigments can better reflect the beauty of nature and are more in line with modern people's pursuit of health and environmental protection.
1.1 Definition of organic pigments
Organic pigments refer to pigments mainly composed of organic compounds. These compounds usually have complex molecular structures and can absorb light of specific wavelengths, thus showing a variety of colors.
1.2
Origin of organic pigments
Ancient times: The earliest pigments used by humans mostly came from nature, such as minerals, plants and animals. For example, red pigments were made from hematite and blue pigments were made from azurite.
Ancient civilizations: In ancient civilizations such as the Egyptians and Romans, people had mastered the technology of extracting dyes from plants, such as madder red and indigo.
Modern development: With the development of organic chemistry, people began to synthesize various organic compounds and discovered many substances with pigment properties. In the mid-19th century, the industrial production of synthetic organic dyes opened a new chapter in the development of organic pigments.
1.3
The development history of organic pigments
Natural dye era: Humans mainly use plants, animals and minerals in nature to make pigments.
Synthetic dye era: Marked by the invention of aniline purple, synthetic dyes developed rapidly and replaced most natural dyes.
·Modern organic pigment era: With the advancement of science and technology, the types and properties of organic pigments are constantly improving, and the scope of application is becoming wider and wider.
1.4 Characteristics of organic pigments
Rich colors: Organic pigments have a very wide range of colors and can be mixed into a variety of colors.
Strong tinting power: Organic pigments have strong tinting power and can achieve good coloring effects with a small amount.
High transparency: Many organic pigments have high transparency and can be used in combination to produce rich and varied color effects.
Poor light resistance:
Compared with inorganic pigments, organic pigments have relatively poor light resistance and are easy to fade.
1.5
Classification of organic pigments
Organic pigments can be classified according to their sources, chemical structures, etc.:
·Natural organic pigments: from plants, animals and minerals.
·Synthetic organic pigments: prepared by chemical synthesis.
·Azo pigments, phthalocyanine pigments, quinacridone pigments, etc.
1.6 Application of organic pigments
Organic pigments are widely used in various fields:
Painting: watercolor, oil painting, acrylic painting, etc.
·Dyeing and weaving: dyeing and weaving natural fibers such as silk, cotton and linen.
·Printing: printing books, magazines, packaging, etc.
·Plastics: coloring plastic products.
·Coatings: used for architectural coatings, automotive coatings, etc.
·Cosmetics: making lipsticks, eye shadows, etc.
Chapter 2: Types of organic pigments
Organic pigments, as the name implies, are mainly derived from organic matter. They are rich in color, have bright colors and good tinting power. According to the different sources, organic pigments can be divided into the following categories:：
2.1 Pigments from plant sources
Plants are one of the most colorful resources in nature. From flowers, fruits to leaves and rhizomes, a variety of pigments can be extracted. Common plant pigments are:
· Alizarin red: from madder root, dark red in color, a common dye in ancient times.
· Indigo: from plants such as Polygonum indigo, dark blue in color, the main dye for denim.
· Gardenia yellow: from gardenia fruit, bright yellow in color, often used in painting and dyeing.
· Onion skin yellow: extracted from onion skin, golden in color, easy to obtain.
2.2 Pigments from Animals
Animals are also an important source of organic pigments. Some insects, shellfish, and specific parts of mammals are rich in pigments.
· Cochineal red: from cochineal, bright red in color, a noble dye.
· Violet: from violet shells, purple in color, with a pearly luster.
· Bone black: made from animal bones, black in color.
2.3 Organic pigments from minerals
Although minerals are generally considered to be the source of inorganic pigments, some minerals contain organic components and can also be extracted from organic pigments. For example:
· Coal black: made from coal, black in color.
2.4 Synthetic organic pigments
With the development of the chemical industry, people can obtain a variety of organic pigments through artificial synthesis. Synthetic organic pigments have the advantages of bright colors, complete color spectrum, good light and heat resistance, etc., and are widely used in various fields.
2.5 Characteristics of organic pigments
· Rich colors: Organic pigments have a very wide range of colors and can be mixed into a variety of colors.
· High transparency: Many organic pigments have high transparency and can be used in layers to produce rich and varied color effects.
· Poor light fastness: Compared with inorganic pigments, organic pigments have relatively poor light fastness and are easy to fade.
2.6 Application of organic pigments
Organic pigments are widely used in painting, dyeing, printing, plastics, coatings and other fields. For example:
· Painting: Organic pigments can be used in watercolor, oil painting, acrylic painting, etc.
· Dyeing: Organic pigments can be used to dye and weave natural fibers such as silk, cotton and linen.
· Printing: Organic pigments can be used to print books, magazines, packaging, etc.
· Plastics: Organic pigments can be used to color plastic products.
Coatings: Organic pigments can be used in architectural coatings, automotive coatings, etc.
Chapter 3: Production of plant pigments
Plants are natural "dye factories" that contain a wealth of colors. Below, we take the production of alizarin red as an example to introduce the production process of plant pigments in detail.
3.1 Production of Alizarin Red
Madder root is the main raw material for making madder red. Madder red is a stable red dye that was widely used for dyeing and weaving in ancient times.
Steps:
1. Collect madder roots: Select madder roots with a longer growth period and wash away the dirt.
2. Drying: Cut the madder roots into small pieces and place them in a cool and ventilated place to dry, or dry them at low temperature.
3. Crushing: Use a grinding tool to crush the dried madder roots into fine powder.
4. Extraction: Put the madder powder into a container, add water or alcohol, heat and boil, and fully extract the pigment.
5. Filter: Filter the extract to remove impurities.
6. Concentrate: Heat and concentrate the filtrate until a thick liquid or solid is obtained.
7. Preparation: Mix the concentrate with an appropriate amount of adhesive (such as gum arabic) to make a pigment.
3.2 Production of other plant pigments
In addition to alizarin red, there are many plants that can be used to make pigments, such as:
·Indigo: Extract indigo by fermenting the leaves of Polygonum tinctorium.
·Gangkine: Boil the fruits of Garcinia to extract the yellow pigment.
·Gardenia yellow: Mash the fruits of Gardenia and soak them in water to extract the yellow pigment.
Precautions for the production of plant pigments:
·Season: The pigment content of plants will vary in different seasons. Generally speaking, the pigment content is higher when collected in the season when plants grow vigorously.
·Solvent: Different plant pigments have different solubility in solvents. Choosing a suitable solvent can improve the extraction efficiency.
·Acidity and alkalinity: Some plant pigments are sensitive to acidity and alkalinity. Pay attention to controlling the pH value of the solution during the extraction process.
·Temperature: High temperature will destroy some pigments, so pay attention to controlling the temperature during extraction.
3.3 Advantages and Disadvantages of Plant Pigments
·Advantages:
o Natural and environmentally friendly
o Rich colors
o Soft colors
·Disadvantages:
o Poor color stability
o Relatively weak coloring power
o Complicated production process
3.4 Application of Plant Pigments
Plant pigments can be used for:
·Painting: making watercolor pigments, oil pigments, etc.
·Dyeing and weaving: dyeing and weaving natural fibers such as silk, cotton and linen.
·Makeup: making natural lipstick, blush, etc.
·Food: making natural food pigments.
Chapter 4: Production of Mineral Pigments
Mineral pigments are one of the earliest pigments used by humans. They have stable colors and good light resistance, and are indispensable materials in traditional painting.
4.1 Types of Mineral Pigments
Common mineral pigments include:
Ochre: The color ranges from yellow to reddish brown and contains iron oxide.
Hematite: The color is reddish brown and the main component is iron oxide.
Azurite: The color is blue and the main component is copper carbonate.
Pyrite: The color is green and the main component is basic copper carbonate.
Ultramarine: It is blue in color and its main component is natural lapis lazuli.
Ochre, Hematite, Azurite, Malachite, Ultramarine
4.2 Production of Mineral Pigments
The production of mineral pigments is relatively simple and mainly includes the following steps:
1. Collection: Collect ore containing pigment components from mines or nature.
2. Crushing: Crushing the ore into small pieces.
3. Grinding: Grinding the crushed ore into fine powder with a grinding tool.
4. Purification: Some minerals need to be purified to remove impurities.
5. Preparation: Mix the ground mineral powder with a binder to make a pigment.
4.3 Characteristics of Mineral Pigments
Color stability: Mineral pigments have very good color stability and are not easy to fade.
Good light resistance: Mineral pigments have strong light resistance and are not easily affected by light.
Strong covering power: Mineral pigments have strong covering power and can cover the base color.
4.4 Application of Mineral Pigments
Mineral pigments are widely used in:
Painting: It is a commonly used pigment in traditional painting.
Ceramics: Used for coloring ceramics.
Architecture: used for exterior wall decoration of buildings.
4.5 Precautions for mineral pigments
Toxicity: Some mineral pigments contain heavy metals and are toxic. Be careful when using them.
Particle size: The particle size of mineral pigments affects the coloring power and transparency of the pigments.
Chapter 5: Pigments from Animals
Animals are also a natural source of pigments. Although the use of animal pigments has gradually decreased with the development of human civilization, their status in history cannot be ignored.
5.1 Cochineal
Cochineal is an insect that parasitizes on cacti. By drying and grinding female cochineal, a bright red dye, cochineal, can be extracted. Cochineal was widely used in dyeing and cosmetics in ancient times.
Cochineal and cochineal red
5.2 Bone black
Bone black is a black pigment obtained by calcining animal bones at high temperatures. Bone black has good adsorption properties and is often used in painting and ink making.
5.3 Squid Ink
Squid ink is a defensive secretion in the body of the squid and a natural black pigment. Squid ink has unique fluidity and luster and is widely used in painting and food additives.
5.4 Advantages and disadvantages of animal pigments
·Advantages:
o Bright colors
o Unique colors
o Some animal pigments have special texture and luster
·Disadvantages
o Limited production
o Complex extraction process
o Harm to animals
5.5 Application of animal pigments
Animal pigments were widely used in ancient times:
·Painting: making murals, oil paintings, etc.
·Dyeing and weaving: dyeing and weaving natural fibers such as silk, cotton and linen.
·Makeup: making lipstick, rouge, etc.
As people's awareness of animal protection increases, the use of animal pigments is becoming less and less, replaced by synthetic pigments and plant pigments.
5.6 Other animal pigments
In addition to the above-mentioned ones, there are many animals that can provide pigments, such as:
·Shells: The inner layer of some shells has a pearly luster and can be ground into pigments.
·Insects: The body fluids or shells of some insects contain pigments.
·Birds: The feathers of some birds can provide color.
Chapter 6: Synthetic organic pigments
With the development of organic chemistry, humans gradually mastered the method of synthesizing organic pigments. Synthetic organic pigments have the advantages of rich colors, complete color spectrum, and stable performance, and have been widely used in modern industry.
6.1 Advantages of synthetic organic pigments
· Rich colors: Synthetic organic pigments have a very wide range of colors and can be mixed into a variety of colors, including colors that are difficult to find in nature.
· Stable performance: Synthetic organic pigments have better light resistance, heat resistance, chemical resistance and other properties than natural organic pigments.
· Large output: Synthetic organic pigments can be produced industrially with large output and low cost.
6.2 Classification of synthetic organic pigments
According to different chemical structures, synthetic organic pigments can be divided into the following categories:
· Azo pigments: The most common type of synthetic organic pigments, with bright colors and wide applications.
· Phthalocyanine pigments: With excellent light resistance, heat resistance, and chemical resistance, they are often used in printing inks, plastic coloring, etc.
· Quinacridone pigments: Bright colors, good light resistance, and are often used in art pigments and automotive coatings.
· Anthraquinone pigments: With good heat resistance and chemical resistance, they are often used in high-temperature coatings.
6.3 Production process of synthetic organic pigments
The production process of synthetic organic pigments is relatively complex and generally includes the following steps:
1. Raw material selection: Select suitable raw materials, such as aniline, naphthalene, etc.
2. Synthesis reaction: Synthesize pigment intermediates through a series of chemical reactions.
3. Coupling reaction: Couple the intermediates to form pigment molecules.
4. Refining: Refine the pigment to remove impurities.
5. Dispersion: Disperse the pigment in a carrier to make a usable pigment product.
6.4 Application of synthetic organic pigments
Synthetic organic pigments are widely used in:
· Paint industry: Manufacture of various paints, such as architectural paints, automotive paints, etc.
· Plastic industry: Coloring plastic products.
· Textile industry: Dyeing and weaving fibers.
· Cosmetic industry: Making cosmetics.
6.5 Environmental impact of synthetic organic pigments
During the production and use of synthetic organic pigments, some harmful substances may be produced, causing pollution to the environment. Therefore, the development of environmentally friendly synthetic organic pigments is the future development direction.
How can the organic pigments produced maintain their bright colors for a long time and exert their greatest artistic effect?This is about the preservation and use of pigments.
7.1 Methods for preserving pigments·
o Dry preservation: After the prepared pigments are fully dried, they are placed in sealed glass bottles or ceramic jars to avoid contact with air.
o Light-proof preservation: Light will accelerate the oxidation and fading of the pigments, so the pigments should be stored in a cool and dry place.
o Moisture-proof preservation: A humid environment will breed mold and destroy the structure of the pigment. Therefore, the container for storing the pigment must be well sealed.
7.2 Tips for color matching of pigments
o Three primary colors: Red, yellow, and blue are the three primary colors of color. By mixing these three colors in different proportions, almost all colors can be mixed.
o Hue wheel: The hue wheel can help us better understand the relationship between colors, so as to mix colors more accurately.
o Contrasting colors: Contrasting colors refer to colors that are 180 degrees apart on the hue wheel. When they are matched together, they can produce a strong visual impact.
o Complementary colors: Complementary colors refer to corresponding colors on the color wheel, which can produce gray when mixed together.
7.3 Application of pigments in different media
o Painting: Organic pigments can be used in a variety of painting forms such as watercolor, oil painting, and acrylic painting.
o Dyeing and weaving: Organic pigments can be used to dye and weave natural fibers such as silk, cotton and linen.
o Makeup: Some natural organic pigments can be used to make cosmetics such as lipstick and eye shadow.
o Others: Organic pigments can also be used in ceramics, murals, decoration and other fields.
Chapter 8: FAQ
In the process of making organic pigments, you may encounter various problems. Below, I will answer some common questions for you.
·* How to choose suitable plants?
Generally speaking, plants with bright colors and hard textures are more suitable for extracting pigments. Common plants include: madder, hematoxylin, comfrey, gardenia, onion skin, etc.
·* How to improve the stability of pigments?
The stability of pigments can be improved by adding appropriate amounts of binders and stabilizers. Common binders include gum arabic, egg white, gelatin, etc.
·* How to deal with poisonous plants or minerals?
When handling poisonous plants or minerals, be sure to wear protective equipment such as gloves and masks to avoid direct contact with the skin and respiratory tract.
· Precautions for making organic pigments
o Pay attention to safety: During the production process, pay attention to fire prevention and explosion prevention, and avoid contact with toxic substances.
o Be patient: Making organic pigments requires a certain amount of patience and carefulness.
o Environmental awareness: Choose natural raw materials to reduce pollution to the environment.
Chapter 9: Conclusion
The development process of organic pigments is from nature to artificial, from simple to complex. With the continuous advancement of science and technology, the types and performance of organic pigments are constantly improving, and they are developing in the direction of richer colors, more stable performance, and more environmentally friendly. In the future, organic pigments will show greater potential in more fields.
Making organic pigments is not only an interesting experiment, but also a way to communicate with nature. By making pigments by hand, we can have a deeper understanding of the mystery of color and experience the joy of creation. I hope this article can inspire your interest and let you try it!