Which statement about the two dope types used for fabric finishes is true?

• A. They are synthetic resins unrelated to fabrics.
• B. They are used for fabric finishes in coat form.
• C. They are used exclusively for metal coatings.
• D. They are used for fabric finishes and are Cellulose Nitrate and Cellulose Acetate Butyrate.

Answer: (D)

Doping fabric for aircraft surfaces relies on coatings that form a tight, weatherproof film from cellulose-based resins. The two main dopes historically used for fabric finishes are cellulose nitrate (nitrocellulose) and cellulose acetate butyrate. This combination is exactly what the statement is describing, so it correctly identifies both materials used for fabric finishes.

The other options mislead: one says the dopes are synthetic resins unrelated to fabrics, which isn’t true since these dopes are cellulose-based coatings applied to fabric. Another claims they’re used exclusively for metal coatings, which ignores their primary use on fabric. The remaining option recognizes that dopes are coatings for fabric, but it doesn’t name the specific two materials, so it’s not as precise as the correct choice.