A Question of Chemistry: What are dyes? | Detailed Explanation

Looking down at your clothes, what color are you wearing? Do you know how the colors on our clothes are produced? That would benefit from the presence of dyes. What are dyes? Because of the birth of dyes, our clothing, bedding, cosmetics, and more articles for daily use can be rich and colorful. Let’s delve deeper into dyes through this article.

What are dyes?

Dyes are different from pigments in that the majority of the former are organic compounds, while the latter are inorganic or organic compounds. Dyes are used to add color to items, making them less prone to fading. They are soluble in water. It comes in both natural and synthetic forms. Natural dyes are generally obtained from plants, such as flowers. Indigo and others are artificial dyes.

Indigo may be the oldest known dye, extracted from plants. At present, the preferred dye for denim is still indigo, and the technology for synthesizing indigo is already very mature.

When it comes to natural dyes, log is currently the only natural dye still in use. Red Aspergillus extracted from the heartwood of cork produces hematoxylin, which is then oxidized to heme during the separation process. The combination of red heme and chromium produces shades of gray and black. It is mainly used for dyeing silk and leather.

Lilac was the first commercially successful synthetic dye, lilac, which appeared in the mid-19th century.

Types of dyes

There are currently many types of dyes on the market, and their classification methods are diverse. This article mainly introduces direct dyes, reactive dyes, acid dyes, basic dyes, and sulphur dyes.

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1.Direct dyes

Direct dyes are often very similar to fabrics and can be used well on textiles. It is water-soluble and has relatively poor wettability. Compared to other dyes, it is usually cheaper.

Direct dyes are used for cotton and paper, as well as pH indicators and biological dyes, carpets, etc. Affordable bed sheets and other items are made from direct dyes.

2.Reactive dyes

Reactive dyes are widely used in the textile industry, but they are most suitable for dyeing various types of cotton fabrics.

It is more washable, light-resistant, and sweat-resistant. It comes in powder, liquid, and paste form. It is soluble in water, making the dyeing process simpler and requiring lower temperatures.

3.Acid dyes

Acid dyes are insoluble in water and not washable, but have good light fastness. Their applications require acidic media.

4.Basic dyes

Basic dyes are soluble in alcohol and methylated alcohol, but not easily soluble in water. The color of this dye is relatively firm. They are mainly used for jute and other purposes. Dyeing is carried out at 98 ℃ and requires slow cooling to prevent the formation of wrinkles.

5.Sulphur dyes

They are insoluble in water and need to be applied under alkaline conditions, requiring oxidation to produce color, and generally producing relatively dark tones. This dye has poor color fastness. They are cheap in price.

Applications of dyes

lUsed to dye clothes

lUsed for hair dyes

lPolishing leather goods, such as shoes and bags

lMake colored cosmetics such as eye shadow and lipstick

lPaint and coatings, etc

Conclusion

To sum up, this article mainly discusses the history, characteristics, classification, and applications of dyes. Different classification standards will result in different types of dye names. This article mainly introduces five common dyes. Thanks to the emergence of dyes, colors have emerged in our textiles, furniture, cosmetics, daily decorations, and more. Thanks to the continuous development and widespread use of synthetic dyes, their cost is becoming increasingly low and their variety is becoming more diverse, further facilitating our lives. What are dyes? From a chemical perspective, it is a substance that can adhere to materials such as fabrics and give them colors; from a humanistic perspective, it is an indispensable part of a better life and a medium for us to preserve the beauty that exists and does not exist in nature.