NEW YORK PLASTERER LICENSE
EXAMINATION 450 PRACTICE
QUESTIONS WITH CORRECT ANSWERS
AND RATIONALES
SECTION 1: PLASTER MATERIALS & COMPOSITION (Questions 170)
Question 1
Which of the following is the primary purpose of plaster in construction?
A) Insulation
B) Surface finishing
C) Structural support
D) Waterproofing
Correct Answer: B
Rationale: Plaster is mainly used to provide a smooth, finished surface on
walls and ceilings, creating an aesthetically pleasing and functional interior.
While plaster can contribute to fire resistance and sound insulation, its
primary purpose is surface finishing.
Question 2
,What is the standard thickness of a plaster coat on interior walls?
A) 1/16 inch
B) 1/4 inch
C) 3/8 inch
D) 1 inch
Correct Answer: C
Rationale: The standard interior plaster thickness is typically about 3/8 inch,
which provides proper coverage, strength, and a durable finish. Thinner coats
may not provide adequate coverage, while thicker coats are unnecessary and
wasteful.
Question 3
Which type of plaster is made by mixing gypsum with water?
A) Lime plaster
B) Gypsum plaster
C) Cement plaster
D) Clay plaster
Correct Answer: B
Rationale: Gypsum plaster is made from gypsum powder (calcium sulfate
hemihydrate) mixed with water. It sets quickly through a chemical reaction
and is primarily used for interior applications due to its smooth finish and
ease of application.
,Question 4
What is the primary ingredient in cement plaster?
A) Gypsum
B) Portland cement
C) Lime
D) Clay
Correct Answer: B
Rationale: Cement plaster, also known as stucco, is primarily made of Portland
cement mixed with sand and water. It is durable, weatherresistant, and
commonly used for exterior applications.
Question 5
Lime plaster is made from:
A) Gypsum and water
B) Portland cement and sand
C) Lime, sand, and water
D) Clay and straw
Correct Answer: C
Rationale: Lime plaster is a traditional material made from lime (calcium
hydroxide), sand, and water. It is breathable, flexible, and has been used for
, centuries in historic buildings. It sets slowly by carbonation (absorbing CO₂
from the air).
Question 6
Which ingredient in plaster provides the primary binding property?
A) Sand
B) Water
C) Cement or lime
D) Fiberglass
Correct Answer: C
Rationale: Cement and lime act as the binding agents that hold plaster
together once it sets. Sand provides bulk and structure, while water initiates
the hydration process.
Question 7
What is the typical watertocement ratio for a standard plaster mix?
A) 1:1
B) 0.5:1
C) 2:1
D) 3:1
EXAMINATION 450 PRACTICE
QUESTIONS WITH CORRECT ANSWERS
AND RATIONALES
SECTION 1: PLASTER MATERIALS & COMPOSITION (Questions 170)
Question 1
Which of the following is the primary purpose of plaster in construction?
A) Insulation
B) Surface finishing
C) Structural support
D) Waterproofing
Correct Answer: B
Rationale: Plaster is mainly used to provide a smooth, finished surface on
walls and ceilings, creating an aesthetically pleasing and functional interior.
While plaster can contribute to fire resistance and sound insulation, its
primary purpose is surface finishing.
Question 2
,What is the standard thickness of a plaster coat on interior walls?
A) 1/16 inch
B) 1/4 inch
C) 3/8 inch
D) 1 inch
Correct Answer: C
Rationale: The standard interior plaster thickness is typically about 3/8 inch,
which provides proper coverage, strength, and a durable finish. Thinner coats
may not provide adequate coverage, while thicker coats are unnecessary and
wasteful.
Question 3
Which type of plaster is made by mixing gypsum with water?
A) Lime plaster
B) Gypsum plaster
C) Cement plaster
D) Clay plaster
Correct Answer: B
Rationale: Gypsum plaster is made from gypsum powder (calcium sulfate
hemihydrate) mixed with water. It sets quickly through a chemical reaction
and is primarily used for interior applications due to its smooth finish and
ease of application.
,Question 4
What is the primary ingredient in cement plaster?
A) Gypsum
B) Portland cement
C) Lime
D) Clay
Correct Answer: B
Rationale: Cement plaster, also known as stucco, is primarily made of Portland
cement mixed with sand and water. It is durable, weatherresistant, and
commonly used for exterior applications.
Question 5
Lime plaster is made from:
A) Gypsum and water
B) Portland cement and sand
C) Lime, sand, and water
D) Clay and straw
Correct Answer: C
Rationale: Lime plaster is a traditional material made from lime (calcium
hydroxide), sand, and water. It is breathable, flexible, and has been used for
, centuries in historic buildings. It sets slowly by carbonation (absorbing CO₂
from the air).
Question 6
Which ingredient in plaster provides the primary binding property?
A) Sand
B) Water
C) Cement or lime
D) Fiberglass
Correct Answer: C
Rationale: Cement and lime act as the binding agents that hold plaster
together once it sets. Sand provides bulk and structure, while water initiates
the hydration process.
Question 7
What is the typical watertocement ratio for a standard plaster mix?
A) 1:1
B) 0.5:1
C) 2:1
D) 3:1
