AZ L-17 Plastering Contractor Exam Questions
and Correct Answers (Verified Answers) Plus
Rationale 2027 Q&A| Instant Download Pdf
1. What is the primary purpose of applying a plaster base coat over a
properly prepared substrate?
a. To provide the final decorative color
b. To increase electrical conductivity
c. To establish a sound, uniform surface for subsequent coats
d. To eliminate the need for curing
Answer: c. To establish a sound, uniform surface for subsequent coats
Rationale: The base coat establishes the foundation of the plaster
system. It helps create a consistent plane, provides appropriate
thickness, and develops a suitable surface for the finish coat to bond
to. It is not primarily intended to provide the final appearance.
2. Which property of plaster is most important for maintaining
adhesion to a properly prepared substrate?
,a. Gloss
b. Bond
c. Color
d. Electrical resistance
Answer: b. Bond
Rationale: Bond refers to the ability of plaster to adhere securely to
the substrate. Adequate substrate preparation, proper mixing,
suitable application, and appropriate curing all contribute to a
durable bond.
3. Before applying plaster to a concrete surface, which condition
should generally be avoided?
a. A clean, sound surface
b. A properly prepared bonding surface
c. A surface contaminated with oil or release agents
d. A surface free of loose material
Answer: c. A surface contaminated with oil or release agents
Rationale: Oil, grease, curing compounds, and similar contaminants
can interfere with adhesion. Concrete should be properly cleaned and
mechanically or chemically prepared as appropriate before plaster is
installed.
, 4. What is the primary function of metal lath in a plaster assembly?
a. To serve as a reinforcing and plaster-supporting base
b. To replace all structural framing
c. To waterproof the building by itself
d. To eliminate the need for control joints
Answer: a. To serve as a reinforcing and plaster-supporting base
Rationale: Metal lath provides a mechanical key and reinforcing
support for plaster. It helps the plaster adhere to the assembly and
distribute stresses, but it is not a substitute for structural framing or a
complete waterproofing system.
5. Why should plaster materials be mixed according to the
manufacturer's or applicable specification requirements?
a. To ensure predictable workability and performance
b. To make the plaster dry instantly
c. To eliminate surface preparation
d. To guarantee that no cracking can occur
Answer: a. To ensure predictable workability and performance
Rationale: Mixing proportions affect workability, strength, shrinkage,
adhesion, and curing behavior. Excess water or improper proportions
can adversely affect the finished plaster.
, 6. What can excessive water in a plaster mix commonly cause?
a. Increased strength in every situation
b. Excessive shrinkage and reduced performance
c. Elimination of curing requirements
d. Improved resistance to all weather conditions
Answer: b. Excessive shrinkage and reduced performance
Rationale: Too much water can increase drying shrinkage and porosity
while reducing the desirable properties of the hardened material.
Proper water content is essential for consistent plaster performance.
7. What is the purpose of a scratch coat?
a. To provide the final decorative texture
b. To create a surface that promotes mechanical bonding with the next
coat
c. To waterproof window assemblies
d. To polish the plaster
Answer: b. To create a surface that promotes mechanical bonding
with the next coat
Rationale: The scratch coat is intentionally textured or scratched while
appropriately firm so that the following coat can mechanically key
into it. It is a foundational layer rather than the finished surface.
and Correct Answers (Verified Answers) Plus
Rationale 2027 Q&A| Instant Download Pdf
1. What is the primary purpose of applying a plaster base coat over a
properly prepared substrate?
a. To provide the final decorative color
b. To increase electrical conductivity
c. To establish a sound, uniform surface for subsequent coats
d. To eliminate the need for curing
Answer: c. To establish a sound, uniform surface for subsequent coats
Rationale: The base coat establishes the foundation of the plaster
system. It helps create a consistent plane, provides appropriate
thickness, and develops a suitable surface for the finish coat to bond
to. It is not primarily intended to provide the final appearance.
2. Which property of plaster is most important for maintaining
adhesion to a properly prepared substrate?
,a. Gloss
b. Bond
c. Color
d. Electrical resistance
Answer: b. Bond
Rationale: Bond refers to the ability of plaster to adhere securely to
the substrate. Adequate substrate preparation, proper mixing,
suitable application, and appropriate curing all contribute to a
durable bond.
3. Before applying plaster to a concrete surface, which condition
should generally be avoided?
a. A clean, sound surface
b. A properly prepared bonding surface
c. A surface contaminated with oil or release agents
d. A surface free of loose material
Answer: c. A surface contaminated with oil or release agents
Rationale: Oil, grease, curing compounds, and similar contaminants
can interfere with adhesion. Concrete should be properly cleaned and
mechanically or chemically prepared as appropriate before plaster is
installed.
, 4. What is the primary function of metal lath in a plaster assembly?
a. To serve as a reinforcing and plaster-supporting base
b. To replace all structural framing
c. To waterproof the building by itself
d. To eliminate the need for control joints
Answer: a. To serve as a reinforcing and plaster-supporting base
Rationale: Metal lath provides a mechanical key and reinforcing
support for plaster. It helps the plaster adhere to the assembly and
distribute stresses, but it is not a substitute for structural framing or a
complete waterproofing system.
5. Why should plaster materials be mixed according to the
manufacturer's or applicable specification requirements?
a. To ensure predictable workability and performance
b. To make the plaster dry instantly
c. To eliminate surface preparation
d. To guarantee that no cracking can occur
Answer: a. To ensure predictable workability and performance
Rationale: Mixing proportions affect workability, strength, shrinkage,
adhesion, and curing behavior. Excess water or improper proportions
can adversely affect the finished plaster.
, 6. What can excessive water in a plaster mix commonly cause?
a. Increased strength in every situation
b. Excessive shrinkage and reduced performance
c. Elimination of curing requirements
d. Improved resistance to all weather conditions
Answer: b. Excessive shrinkage and reduced performance
Rationale: Too much water can increase drying shrinkage and porosity
while reducing the desirable properties of the hardened material.
Proper water content is essential for consistent plaster performance.
7. What is the purpose of a scratch coat?
a. To provide the final decorative texture
b. To create a surface that promotes mechanical bonding with the next
coat
c. To waterproof window assemblies
d. To polish the plaster
Answer: b. To create a surface that promotes mechanical bonding
with the next coat
Rationale: The scratch coat is intentionally textured or scratched while
appropriately firm so that the following coat can mechanically key
into it. It is a foundational layer rather than the finished surface.
