Chapter 20 Coating Defects

Question 1

1. Non-drying films (failure to cure) may be caused by:

Answer 1

• Not adding the cure to the base
• Adding the wrong cure
• Not adding the correct amount of cure during mixing

Question 2

2. Some of the problems that can be caused by amine blush are:

Answer 2

Surface tackiness or greasiness
Incomplete cure
Poor adhesion
Poor adhesion on over-coating
Coating discoloration over time
Poor gloss retention

Question 3

3. Runs, sags, and wrinkles may be caused by:

Answer 3

Applying the coating too thickly
Using too much thinner or using the wrong thinner
Surface too hot to apply the coating
Applying a coating at the end of its pot life
Wrong thixotrope used in manufacturing
Improper spray technique

Question 4

4. _________ is a powdery, friable layer on the surface of a coating that is most common with epoxy coatings.

Answer 4

Chalking

Question 5

Cratering may be caused by:

Answer 5

Air trapped in the wet film

Improper mixing procedures

Question 6

6. Voids are typically caused by:

Answer 6

When a mixer is run too fast

Question 7

7. Pinholes are:

Answer 7

Very small holes in a coating, typically caused by painting over an inorganic zinc coating or sprayed metal coating.

Question 8

8. A common cause of blistering is:

Answer 8

Entrapped solvents in film
High humidity
Excessive wind surface drying
Incorrect application temperatures
Dirt, Dust, Grease, Retained Solvents

Question 9

9. Cracking of a coating is noted:

Answer 9

When the crack extends to the substrate

Question 10

10. Checking can be described as:

Answer 10

Fine cracks in the surface of a coating that don’t extend through to the substrate

Question 11

11. Adhesion failures may be caused by:

Answer 11

Contamination on the surface
Wrong surface preparation specified
Failure to inspect surface preparation
Insufficient surface profile 
Exceeding the topcoat window
Application of incompatible coating
Applying the coating to a glossy surface

Question 12

12. What is Cissing? Or fisheyes or crawling

Answer 12

A term for surface breaks in the film that reveal the substrate resulting from grease or oil residue on substrate