Question

A process by which cellulosic fabric is treated with sulphuric acid to produce a transparent and stiffer fabric:

• A. \( \text{Parchmentisation} \)
• B. \( \text{Calendaring} \)
• C. \( \text{Emerizing} \)
• D. \( \text{Mercerisation} \)

Hint:

Parchmentisation is named after "Parchment" (stiff animal skin paper) because the finish gives the cotton a similar stiff, translucent quality.

Answer 1

The Correct Option is A

Concept: Chemical finishes can alter the physical structure of cellulosic fibers (like cotton) to create specific aesthetic effects.

Step 1: Analyze the effect of acid on cotton.
When a fine cotton fabric (like lawn) is briefly treated with concentrated sulphuric acid, the surface of the cellulose partially dissolves and then hardens. This process is called Parchmentisation. It makes the fabric permanently transparent, crisp, and stiff, resulting in a fabric known as "Organdy."

Step 2: Evaluate other processes.

• Mercerisation: Treatment with caustic soda to increase luster and strength.
• Emerizing: A mechanical finish to create a "suede" or "peach" feel using abrasive rollers.
• Calendaring: Using heavy rollers to smooth or glaze the fabric.