Overview:
This book, written in 1906, delves into the fascinating world of hat manufacturing through the lens of chemistry. Author Watson Smith, a lecturer in chemical technology, presents a series of lectures delivered to the Hat Manufacturers’ Association. The book covers a range of topics crucial to hat making, from the fundamental properties of textile fibers like wool, fur, and hair, to the intricacies of water, acids, alkalis, and mordants. Smith emphasizes the direct impact of scientific understanding and proper process control on the quality, longevity, and cost-effectiveness of the hat-making process. He highlights the struggles of British hat makers against the growing competition from German manufacturers and urges them to embrace scientific knowledge and training.
Key Findings:
- The importance of scientific knowledge in hat manufacturing: Smith argues that the British hat industry needs to embrace science to overcome the challenges of global competition.
- The significance of the “veneering process” for dyeing: This process, invented in 1887 by F.W. Cheetham, allowed for a more even and durable dyeing of hats, addressing a significant challenge in the industry.
- The detrimental effect of hard water: Smith details how impurities in water can waste soap, damage dyes, and interfere with mordanting processes.
- The importance of understanding the chemical nature of dyes: By understanding the chemical properties of dyes, manufacturers can make informed decisions about how to apply them and achieve desired colors and shades.
Learning:
- Textile Fibres: The reader will learn about the differences between vegetable and animal fibres, their chemical compositions, and how they react to various treatments. Important points include:
- Wool: The unique structure of wool fibers, particularly the scaly covering, is key to its felting properties. Learn about the impact of “dead wool” and “kempy” wool on felting.
- Fur: The “carrotting” process used to improve the felting properties of fur involves treatment with nitric acid and mercuric nitrate. Smith suggests alternatives for achieving better results while minimizing damage to the fibers.
- Silk: Understand the differences in structure and properties between wool and silk. Learn about the “silk-glue” (sericin) and its removal in the ungumming process.
- Water: The reader will understand the importance of water quality in the hat making process and how various impurities can affect dyeing and other operations. Key points include:
- Hardness: Learn about the sources of water hardness (temporary and permanent), its impact on soap consumption, and methods for softening hard water.
- Iron and other impurities: Understand the detrimental effects of iron and other contaminants in water on dyeing processes.
- Testing for impurities: Learn about basic tests for identifying and quantifying impurities in water.
- Acids and Alkalis: This section explores the chemistry of acids and alkalis, their effects on fibres, and their use in various processes.
- Indicators: Learn about litmus, phenolphthalein, and Congo red as indicators of acidity and alkalinity.
- Mordants: Discover how mordants are used to fix dyes to fabrics and the importance of understanding the chemical properties of mordants to achieve desired results.
- Dyeing: The reader will explore the different types of dyestuffs and their applications in dyeing wool and felt. Key points include:
- Substantive and adjective dyes: Learn about the differences between these two types of dyes and their methods of application.
- Coal-tar dyes: The book provides a fascinating look at the development and use of these powerful, synthetic dyes and their unique properties.
- The importance of colour theory: Smith explains the basics of color theory, the role of complementary colours, and the concept of absorption spectra.
- The science behind dyeing black: Understand why a mixture of different dyes is often needed to achieve a true black shade and the challenges of dyeing black on highly-proofed felt.
Historical Context: The text is written during a time of significant change in the hat manufacturing industry. British hat makers are facing increased competition from German manufacturers, who are embracing scientific methods and innovation. This competition is driving the need for greater efficiency and better quality in British hat making.
Facts:
- Cotton fibers are spirally twisted tubes: This is observed under a microscope and contributes to cotton’s strength and ability to absorb water.
- Flax fibers resemble bamboo: This is due to their jointed appearance, which is a distinguishing feature compared to other fibers.
- Cotton-silk grows in the Camaroons and the Gold Coast: This is a valuable and beautiful, lustrous fiber, chemically distinct from cotton and flax.
- Animal fibres contain nitrogen: This is one key difference between animal and vegetable fibers.
- Wool and fur contain sulphur: This element is unique to animal fibers and can be detected using tests like the alkaline lead solution.
- Dead wool does not felt well: This is due to the degradation of the fibers, including a decrease in the number and size of scales.
- Wool and fur can absorb a significant amount of moisture: This varies depending on the amount of grease present and is an important factor when purchasing raw materials.
- Hot water assists in the felting process: This is because it softens the fibers and helps the scales interlock.
- Boiling water can damage wool fibers: This makes it important to minimize the use of boiling processes in dyeing and other treatments.
- Wool and fur decompose when heated to a high temperature: This releases ammonia and sulfur-containing vapors, indicating the presence of nitrogen and sulfur in the fibers.
- Nitric acid turns wool and fur yellow: This is used in the “carrotting” process to enhance felting properties but can also damage the fibers.
- Caustic alkalis (soda and potash) damage wool and fur: This can be seen in the recovery of indigo from dyed woolen rags where the wool dissolves in hot caustic soda.
- Alkaline carbonates (like soda ash) are less damaging to wool and fur than caustic alkalis: This is important for scouring and washing processes.
- Lime in water or otherwise acts injuriously to wool and fur, rendering it brittle: This highlights the importance of using soft water in hat making.
- Sulphuretted hydrogen is a good test for sulphur in wool, fur, and hair: This test involves the formation of black sulfide of lead.
- Basic zinc chloride dissolves silk but not wool or vegetable fibers: This is used in a method for determining the percentage of silk in a mixed fabric.
- Water is a compound of hydrogen and oxygen: This is a fundamental chemical fact that forms the basis of many other reactions.
- Oxygen gas is a supporter of combustion: This is demonstrated by the fact that it can ignite a red-hot match.
- Hydrogen gas is a combustible gas: This is demonstrated by its burning in air.
- Potassium reacts with water to release hydrogen gas, which ignites: This demonstrates the reaction of a metal with water, releasing a combustible gas.
Statistics:
- Cotton fibers vary from 2.5 to 6 centimeters in length and 0.017 to 0.05 millimeters in breadth: This gives a sense of the scale of cotton fibers.
- Raw cotton contains about 5% impurities: This highlights the importance of cleaning raw materials for better dyeing and processing.
- Wool can absorb from 8 to 10% moisture in dry weather and 30 to 50% in damp conditions: This highlights the importance of moisture testing when purchasing wool.
- The atmospheric pressure at the surface of the earth is 15 pounds per square inch: This is the pressure that water must overcome to boil.
- Water boils at 212°F (100°C) at sea level: This is a fundamental property of water.
- The latent heat of water is 79 heat units: This means that 79 units of heat are needed to melt 1 kilogram of ice.
- The latent heat of steam is 536 heat units: This means that 536 units of heat are needed to convert 1 kilogram of water into steam.
- The monthly consumption of soap in London is 1,000,000 kilograms (about 1000 tons): This highlights the scale of soap consumption.
- The hardness of the Thames water means the use of 230,000 kilograms (nearly 230 tons) more soap per month than if soft water were used: This demonstrates the significant impact of water hardness on soap consumption.
- The “yolk” or “suint” in wool contains a substance resembling a fat called cholesterol, which is of great therapeutical value: This is a reminder that waste products from industry can have valuable applications.
- One ton of Lancashire coal yields about 12 gallons of coal-tar: This is a typical yield for coal distillation.
- The 12 gallons of coal-tar yield 1-1/10 lb. of benzene, 9/10 lb. of toluene, 1½ lb. of carbolic acid, between 1/10 and 2/10 lb. of xylene, 6½ lb. of naphthalene, and ½ lb. of anthracene: This shows the proportions of valuable products obtained from coal-tar.
- 0.623 lb. of Magenta will dye 500 yards of flannel, 27 inches wide, a full shade: This demonstrates the impressive dyeing power of coal-tar dyes.
- 2.25 lb. of Alizarin (20%) will dye 255 yards of Printers’ cloth a full Turkey red: This shows the dyeing power of Alizarin.
- Two drops of a violet dye solution can dye a skein of silk a bright full shade of violet: This highlights the intense tinctorial power of some coal-tar dyes.
- The mud or precipitate that accumulates in logwood black dye baths amounts to no less than 25% of the weight of the copperas used: This indicates the potential for waste and inefficiency in poorly-managed dye baths.
Terms:
- Cellulose: A complex carbohydrate found in plants, forming the main component of cotton, flax, and other vegetable fibers.
- Fibroïn: The protein that makes up the core of the silk fiber.
- Sericin: The silk-glue or silk-gum that surrounds the fibroïn fiber.
- Hygroscopicity: The ability of a substance to absorb moisture from the air.
- Ebullition: The process of boiling, where a liquid changes into a vapor.
- Latent heat: Heat that is absorbed or released during a change of state (solid to liquid, liquid to gas) but is not detectable by a thermometer.
- Specific gravity: The ratio of the density of a substance to the density of water.
- Mordant: A substance used to fix a dye to a fabric, often a metal salt.
- Acid salt: A salt formed by the partial neutralization of an acid by a base.
- Basic salt: A salt formed by the partial neutralization of a base by an acid.
Examples:
- The “carrotting” process: This involves treating fur with nitric acid and mercuric nitrate to increase its felting properties. This example demonstrates the use of a chemical process to modify the properties of a textile fiber.
- The “veneering” process: This process adds a layer of unproofed wool or fur to the surface of a proofed hat body, allowing for better and more durable dyeing.
- The “indigo-vat” method: This involves reducing indigo blue to soluble indigo white, which can then dye fabrics. The indigo white then oxidizes back to insoluble indigo blue, fixing the dye to the fabric.
- The production of black ash: This process involves combining salt-cake, limestone, and coal to produce sodium carbonate.
- The production of nitrobenzene: This involves reacting benzene with nitric acid, creating a substance used in the production of aniline.
- The production of aniline: This process involves reducing nitrobenzene with hydrogen gas, producing a key component of many dyes.
- The production of Methyl Green: This dye is made by reacting Methyl Violet with methyl chloride. This shows how modifying the chemical structure of a dye can create a new color.
- The dyeing of cotton with Alizarin: This example demonstrates the use of a mordant to fix a polygenetic dye to a fabric.
- The dyeing of felt hats deep black: This example highlights the challenges of dyeing highly-proofed felt and the use of a mixture of dyes to achieve the desired color.
- The production of colored sealing wax: This involves mixing shellac and pigments, demonstrating how an insoluble pigment can be incorporated into a resin.
Conclusion:
This book provides a fascinating glimpse into the chemical world of hat making in the early 20th century. Watson Smith clearly demonstrates the importance of scientific knowledge and process control in achieving successful and efficient hat manufacturing. He highlights the need for British hat makers to embrace science and innovation to remain competitive in a global market. The book also reveals the complexity of dyeing processes and the significance of understanding the chemical properties of dyes and mordants. Whether you are interested in the history of hat making, the science of textiles, or the practical applications of chemistry, this book offers a valuable and insightful read.