C33 Paint and Coating Types 5

Question 1

Which coating is most appropriate for painting a galvanized metal roof that has been weathered for two years?

Accepted Answer

Direct-to-metal (DTM) acrylic or a galvanized metal primer

Answer

Weathered galvanized metal should be coated with a DTM acrylic or a primer specifically formulated for galvanized surfaces to ensure adhesion without saponification.

Question 2

A 'two-component' (2K) polyurethane topcoat differs from a single-component product mainly because:

Accepted Answer

It requires mixing a base and an isocyanate hardener before use and provides a chemically crosslinked film

Answer

Two-component polyurethanes mix a polyol base with an isocyanate hardener that crosslink into an extremely hard, chemical-resistant film far superior to single-component versions.

Question 3

When a specification calls for a 'vapor barrier' coating on interior concrete walls, the contractor should select:

Accepted Answer

High-build epoxy or bituminous coating with very low moisture vapor transmission

Answer

Vapor barrier coatings like high-build epoxies or bituminous products have extremely low moisture vapor transmission rates (MVTR) sufficient to retard moisture migration through concrete.

Question 4

Zinc-rich primers are used primarily on structural steel because zinc:

Accepted Answer

Acts as a sacrificial anode, corroding preferentially to protect the steel substrate

Answer

Zinc is anodic to steel; when exposed, it corrodes first, providing galvanic (cathodic) protection to the underlying steel and preventing rust.

Question 5

A contractor must coat a surface immersed in water. Which generic coating type is most appropriate?

Accepted Answer

Coal tar epoxy or underwater epoxy

Answer

Coal tar epoxies and underwater-grade epoxies are specifically formulated for continuous immersion service, providing excellent water and chemical resistance.

C33 - C-33 California Painting Contractor License Practice Test

C33 - C-33 California Painting Contractor License Practice Test

C33 Paint and Coating Types 5