Question

Which one of the following colour is obtained by using the compounds as mordants with cochineal dye?

• A. Scarlet
• B. Crimson
• C. Purple
• D. Pink

Hint:

Remember the classic mordant-dye effects: Alum + Cochineal = Crimson; Tin + Cochineal = Bright Scarlet; Iron + Cochineal = Purple/Grey.

Answer 1

The Correct Option is A

Step 1: Understanding the Concept:
Cochineal is a natural red dye extracted from the dried bodies of female cochineal insects (Dactylopius coccus).
The active coloring agent is carminic acid.
Natural dyes require chemical mordants (usually metal salts) to fix the dye to the fiber, and different mordants can produce completely different colors from the same dye bath.

Step 2: Detailed Explanation:
The interaction of carminic acid with different metal ions produces a range of colors:
Aluminium (Alum): Produces a rich, deep crimson-red color.
Tin (Stannous chloride): Acts as a brightener.
When tin compounds are used as mordants with cochineal, they yield a brilliant, vivid scarlet red.
This specific combination became historically famous for dyeing the woolen uniforms of the British Redcoats.
Iron (Ferrous sulfate): Saddens the dye, shifting the color toward purple or dark grey.
Therefore, scarlet is the classic brilliant color obtained by using specific tin-based mordant compounds with cochineal.

Step 3: Final Answer:
The color obtained by using tin-based mordant compounds with cochineal dye is Scarlet.