Do you know how wool is different from other fibers?
- It’s completely smooth
- It’s less prone to wrinkles
- It’s more hygroscopic
- It’s made entirely of proteins
Correct Answer: It’s more hygroscopic
Correct Answer Explanation: Wool’s hygroscopic nature means it absorbs more moisture from the air than other fibers like cotton. This helps it feel warmer and more comfortable.
What’s the main ingredient in a natural soap found on wool?
- Potassium
- Magnesium
- Carbon
- Sulfur
Correct Answer: Potassium
Correct Answer Explanation: Wool naturally contains a soapy substance called yolk or suint, which is composed of potash salts of fatty acids.
How can you remove dirt and grease from wool without damaging the fibers?
- Using a highly acidic solution
- Using a highly alkaline solution
- Using a soapy solution
- Using a bleach solution
Correct Answer: Using a soapy solution
Correct Answer Explanation: Wool is sensitive to alkalies, so using soap is a safe and effective way to clean it.
Why was the invention of dyeing machinery a big deal in the wool industry?
- It allowed for larger-scale production
- It made it easier to dye delicate fabrics
- It made the process safer for workers
- It allowed for more precise color control
Correct Answer: It allowed for larger-scale production
Correct Answer Explanation: Dyeing machinery increased efficiency and productivity, meeting the growing demand for woolen fabrics in the 19th century.
What’s the key difference between a direct dye and a mordant dye?
- Direct dyes are more expensive
- Direct dyes don’t require a mordant
- Mordant dyes are more colorful
- Mordant dyes are better for cotton
Correct Answer: Direct dyes don’t require a mordant
Correct Answer Explanation: Direct dyes have a direct affinity for the fibre and can dye it without the aid of mordants. Mordant dyes need a second body (mordant) to fix the color.
How did the discovery of coal tar dyes change the dyeing industry?
- It made dyeing more affordable
- It increased the demand for wool
- It allowed for more vibrant colors
- It made dyeing more sustainable
Correct Answer: It allowed for more vibrant colors
Correct Answer Explanation: Coal tar dyes provided a wider range of colors than natural dyes, creating a revolution in the dyeing industry.
What’s the special trick that makes indigo vat dyeing work?
- Indigo is dissolved in a solvent
- Indigo is combined with a mordant
- Indigo is reduced to a soluble form
- Indigo is combined with a bleaching agent
Correct Answer: Indigo is reduced to a soluble form
Correct Answer Explanation: Indigo is insoluble in water, but it can be dissolved by reducing agents in a vat, allowing it to dye the fabric. Then, when exposed to air, it oxidizes back to its blue form.
How can you create a shot effect in a fabric?
- Dyeing the fabric with two different colors
- Dyeing the fabric with a special mordant
- Dyeing the fabric with a direct dye
- Dyeing the fabric with a vat dye
Correct Answer: Dyeing the fabric with two different colors
Correct Answer Explanation: Shot effects are achieved by dyeing the cotton and wool of a mixed fabric in different colors, creating a visual variation.
Which type of fabric is made from a blend of wool and silk?
- Linen
- Satin
- Gloria
- Velvet
Correct Answer: Gloria
Correct Answer Explanation: Gloria is a lustrous fabric woven from wool and silk, often used for dress goods. It can be dyed in one color or with two different colors for shot effects.
What happens to wool if it’s exposed to caustic alkalies?
- It becomes more durable
- It changes color
- It becomes softer
- It becomes weakened
Correct Answer: It becomes weakened
Correct Answer Explanation: Caustic alkalies can damage the wool fibers, so their use in dyeing is avoided.
How is wool fat used in the industry?
- It is used as a natural fertilizer
- It is used to make soap
- It is used to produce oil
- It is used to make medicine
Correct Answer: It is used to make soap
Correct Answer Explanation: Wool fat, also known as Yorkshire grease, is recovered from used scouring liquors and is used in various industries, including ointment production and soap-making.
What’s the difference between worsted and woolen yarns?
- Worsted yarns are spun from long fibers
- Worsted yarns are spun from short fibers
- Worsted yarns are not subjected to felting
- Worsted yarns are subjected to felting
Correct Answer: Worsted yarns are not subjected to felting
Correct Answer Explanation: Worsted yarns are spun from long fibers that are not subjected to felting, creating a smoother, more even fabric. Woollen yarns, on the other hand, are spun from short fibers that are subjected to felting, resulting in a softer, more textured fabric.
Why is the hydrosulphite vat a better alternative to the fermentation vat for indigo dyeing?
- It produces brighter colors
- It is less prone to problems
- It is more affordable
- It is more sustainable
Correct Answer: It is less prone to problems
Correct Answer Explanation: Hydrosulphite vats use chemical reactions to reduce indigo, making them more efficient and less problematic than fermentation vats, which rely on bacterial activity.
What is the main advantage of dyeing wool with acid dyes?
- Acid dyes produce more vibrant colors
- Acid dyes are better for cotton
- Acid dyes are easier to apply
- Acid dyes are more resistant to fading
Correct Answer: Acid dyes are more resistant to fading
Correct Answer Explanation: Acid dyes are fast dyes, meaning they resist fading and are often used to create colors that are resistant to sunlight, washing, and other factors that can damage color.
How can you identify the dyes used in a fabric sample?
- By analyzing the fabric’s fiber content
- By examining the fabric’s texture
- By observing color changes with different chemical reagents
- By looking at the fabric’s dye lot number
Correct Answer: By observing color changes with different chemical reagents
Correct Answer Explanation: Dye testing involves treating the fabric with different chemicals to see how the color changes, providing clues about the dyes used.
What was a major challenge in dyeing union fabrics (blends of cotton and wool)?
- Achieving uniform shades
- Maintaining the fabric’s texture
- Preventing fading
- Controlling the dyeing time
Correct Answer: Achieving uniform shades
Correct Answer Explanation: Direct dyes revolutionized dyeing union fabrics because they allowed dyers to achieve uniform shades on both the cotton and wool fibers, which previously presented a challenge due to their different dyeing properties.
What are the two main types of wool bleaching?
- Sulphur and peroxide bleaching
- Acid and alkaline bleaching
- Color and black-and-white bleaching
- Natural and synthetic bleaching
Correct Answer: Sulphur and peroxide bleaching
Correct Answer Explanation: The two main methods of wool bleaching are sulphur bleaching and peroxide bleaching, each with their own advantages and disadvantages.
How can you prevent wool from felting during the dyeing process?
- By using a high temperature
- By using a low temperature
- By adding a mordant
- By adding a felting agent
Correct Answer: By using a low temperature
Correct Answer Explanation: Wool fibers have a tendency to felt together when boiled and handled, so dyers need to be careful to prevent this by using lower temperatures.
Why are some colors considered “fast” while others are considered “fugitive”?
- Fast colors are more vibrant
- Fast colors are more affordable
- Fast colors are more resistant to fading
- Fast colors are easier to apply
Correct Answer: Fast colors are more resistant to fading
Correct Answer Explanation: Fast dyes resist fading from washing, sunlight, and other factors. Fugitive dyes, on the other hand, are prone to fading.
What are Kempy fibers?
- A type of wool fiber that is very soft
- A type of wool fiber that is very strong
- A type of wool fiber that is difficult to dye
- A type of wool fiber that is very rare
Correct Answer: A type of wool fiber that is difficult to dye
Correct Answer Explanation: Kempy fibers are peculiar wool fibers with a white, horny appearance that don’t felt or dye well.
What is the common name for wool grease recovered from scouring liquors?
- Wool fat
- Lanolin
- Yorkshire grease
- Suint
Correct Answer: Yorkshire grease
Correct Answer Explanation: Wool grease, also known as Yorkshire grease, is a valuable by-product recovered from scouring liquors and contains wool fat, which is used in various industries, including ointment production.
Which type of bleaching is preferred for wool?
- Sulphur bleaching
- Peroxide bleaching
- Vat bleaching
- Acid bleaching
Correct Answer: Peroxide bleaching
Correct Answer Explanation: Peroxide bleaching is often preferred for wool because it does not leave the wool yellowed like sulphur bleaching can.
What is the typical range of oil used in batching wool?
- 1-3%
- 5-8%
- 7-15%
- 20-25%
Correct Answer: 7-15%
Correct Answer Explanation: The amount of oil used in batching wool varies depending on the wool type, but the typical range is between 7% and 15%.
What is the typical concentration of Glauber’s salt in a dye-bath for union fabrics?
- 2-1/2 oz per gallon of water
- 4-1/4 oz per gallon of water
- 6-1/4 oz per gallon of water
- 8-1/4 oz per gallon of water
Correct Answer: 6-1/4 oz per gallon of water
Correct Answer Explanation: Glauber’s salt is a chemical used to adjust the dyeing process of union fabrics, and a typical concentration is 6-1/4 oz per gallon of water.
What does the term “staple” refer to in wool?
- The color of the wool
- The texture of the wool
- The length of the wool fibers
- The strength of the wool fibers
Correct Answer: The length of the wool fibers
Correct Answer Explanation: Staple refers to the length of wool fibers, which can vary depending on the breed of sheep.
How much of its weight in water vapor can wool absorb?
- 10%
- 25%
- 50%
- 75%
Correct Answer: 50%
Correct Answer Explanation: Wool’s hygroscopic nature allows it to absorb up to 50% of its weight in water vapor, which contributes to its warmth and comfort.
What is a mordant used for in dyeing?
- To create vibrant colors
- To fix a dye-stuff to the fiber
- To soften the wool fibers
- To increase the dyeing time
Correct Answer: To fix a dye-stuff to the fiber
Correct Answer Explanation: Mordants are chemical compounds that help to fix dye-stuffs to the wool fibers, ensuring that the color is durable and resistant to fading.
Which of the following is a mordant dye?
- Indigo
- Alizarine
- Direct dye
- Vat dye
Correct Answer: Alizarine
Correct Answer Explanation: Alizarine is a classic example of a mordant dye, where the color produced depends on the metal oxide used as the mordant.
What does a well-set woad vat look like?
- Bright blue
- Olive brown
- Dark brown
- Yellowish green
Correct Answer: Olive brown
Correct Answer Explanation: A well-set woad vat (for indigo dyeing) will have a characteristic olive-brown color, while an oxidized vat will appear dark brown.
Which of the following is NOT a natural dye?
- Indigo
- Logwood
- Alizarine
- Diamine
Correct Answer: Diamine
Correct Answer Explanation: Diamine is a direct dye, a type of synthetic dye developed in the late 19th century, while the others are natural dyes.
What is the typical concentration of indigo in a working vat?
- 1/2 lb per gallon
- 1 lb per gallon
- 2 lb per gallon
- 3 lb per gallon
Correct Answer: 1 lb per gallon
Correct Answer Explanation: A typical indigo vat might contain 1 lb of indigo per gallon of water, creating a solution that can dye the fabric a fast blue shade.
How much bisulphite of soda is needed to prepare a hydrosulphite vat?
- 30 lb
- 60 lb
- 90 lb
- 120 lb
Correct Answer: 90 lb
Correct Answer Explanation: A hydrosulphite vat is prepared from a significant amount of bisulphite of soda, typically around 90 lb, to create a reducing agent for the indigo dyeing process.
How does the presence of lime in an indigo vat affect the dyeing results?
- It creates a brighter blue shade
- It creates a darker blue shade
- It weakens the color
- It makes the dye more durable
Correct Answer: It weakens the color
Correct Answer Explanation: Impurities like lime in an indigo vat can result in loose shades, affecting the durability and overall appearance of the dyed fabric.
What color is often achieved on wool using logwood and a chrome mordant?
- Deep red
- Dark navy blue
- Bright green
- Light purple
Correct Answer: Dark navy blue
Correct Answer Explanation: Logwood is traditionally used to dye dark navy blue shades on wool, often with a chrome mordant to create fast colors.
What are the two main types of direct dyes?
- Diamine and Benzo dyes
- Alizarine and Indigo
- Vat and Mordant dyes
- Acid and Basic dyes
Correct Answer: Diamine and Benzo dyes
Correct Answer Explanation: Diamine and Benzo dyes are two of the most well-known types of direct dyes, which have a direct affinity for wool and cotton fibers, making them suitable for dyeing union fabrics.
What is the main difference between direct dyes and vat dyes?
- Direct dyes are more vibrant
- Vat dyes are more durable
- Vat dyes require a mordant
- Direct dyes are more expensive
Correct Answer: Vat dyes are more durable
Correct Answer Explanation: Vat dyes are known for their durability, particularly with indigo vat dyeing, which produces fast blue shades that are resistant to fading.
Why is it important to understand the affinity of direct dyes for cotton and wool at different temperatures?
- To create different color effects
- To prevent the fabric from shrinking
- To ensure even shade distribution
- To minimize the dyeing time
Correct Answer: To ensure even shade distribution
Correct Answer Explanation: Direct dyes have different affinities for cotton and wool at different temperatures, so it’s crucial to understand this relationship to achieve even shades on union fabrics.
What can be added to a dye bath to influence the dye-stuff’s affinity for cotton and wool?
- Salt
- Vinegar
- Borax
- All of the above
Correct Answer: All of the above
Correct Answer Explanation: Chemicals like salt, vinegar, and borax can be used to adjust the dyeing process and influence the dye-stuff’s affinity for different fibers, helping dyers to achieve the desired results.
What is cross-dyeing?
- A method for dyeing a fabric with multiple colors
- A method for dyeing a fabric with a single color
- A method for dyeing a fabric with a mordant
- A method for dyeing a fabric with a direct dye
Correct Answer: A method for dyeing a fabric with multiple colors
Correct Answer Explanation: Cross-dyeing involves dyeing a fabric with different colors, typically using acid dyes to achieve varied shades in the final fabric.
How much raw wool can contain pure wool fiber?
- Up to 75%
- Up to 50%
- Up to 25%
- Up to 10%
Correct Answer: Up to 25%
Correct Answer Explanation: Raw wool can contain a relatively low percentage of pure wool fiber, with the rest consisting of impurities like yolk, dirt, and other substances, highlighting the need for effective scouring.
What percentage of yolk can raw Merino wool contain?
- Up to 15%
- Up to 25%
- Up to 35%
- Up to 47%
Correct Answer: Up to 47%
Correct Answer Explanation: Raw Merino wool is known for its high yolk content, with some samples containing as much as 47%, illustrating the significant impurities that need to be removed during scouring.
How much sulphur is used in a typical sulphur bleaching process?
- 2 to 4% of the wool’s weight
- 4 to 6% of the wool’s weight
- 6 to 8% of the wool’s weight
- 8 to 10% of the wool’s weight
Correct Answer: 6 to 8% of the wool’s weight
Correct Answer Explanation: Sulphur bleaching involves using a specific percentage of sulphur, typically between 6% and 8% of the wool’s weight, to lighten the color of the wool.
What is the typical volume of hydrogen peroxide used for wool bleaching?
- 5-volume
- 10-volume
- 15-volume
- 20-volume
Correct Answer: 10-volume
Correct Answer Explanation: 10-volume peroxide of hydrogen is a common strength of peroxide solutions used for wool bleaching, providing effective bleaching without damaging the wool fibers.
How much bichromate of potash is needed for full shades when using Alizarine?
- 1% of the Alizarine’s weight
- 2% of the Alizarine’s weight
- 3% of the Alizarine’s weight
- 4% of the Alizarine’s weight
Correct Answer: 3% of the Alizarine’s weight
Correct Answer Explanation: Alizarine, a mordant dye, requires a specific amount of bichromate of potash to achieve full shades, typically around 3% of its weight.
This 1902 book on dyeing woollen fabrics would be of great interest to anyone who wants to learn more about:
- The history of fashion
- The textile industry
- The chemistry of dyes
- All of the above
Correct Answer: All of the above
Correct Answer Explanation: This book covers a wide range of topics, including the history of textile dyeing, the properties of wool, and the chemistry of dyes, making it a valuable resource for anyone interested in these subjects.