Question

In which of the following acid biting methods, the air bubbles are not formed?

• A. Dutch Mordant
• B. Ferric Chloride
• C. Ferric Bromide
• D. Nitric Acid

Hint:

For etching, remember this key difference: Nitric Acid = Bubbles and Fumes. Ferric Chloride = No Bubbles, No Fumes (much safer!).

Answer 1

The Correct Option is B

Step 1: Understand the chemical reactions in etching. When certain acids react with metals like zinc or copper, they produce hydrogen gas, which forms bubbles on the plate.
Step 2: Analyze the mordants (biting agents).

Nitric Acid is famous for its vigorous reaction that produces bubbles, which must be brushed away to ensure an even etch.
Ferric Chloride is technically a corrosive salt, not an acid. It corrodes copper through a process of oxidation and reduction that does not produce gas bubbles. This is why it is considered a safer and more controllable mordant, as it bites very cleanly.
Dutch Mordant (hydrochloric acid mixed with potassium chlorate) also produces bubbles, though often less vigorously than nitric acid.