Chapter 20 Coating Defects Flashcards
1
Q
- Non-drying films (failure to cure) may be caused by:
A
- Not adding the cure to the base
- Adding the wrong cure
- Not adding the correct amount of cure during mixing
2
Q
- Some of the problems that can be caused by amine blush are:
A
Surface tackiness or greasiness Incomplete cure Poor adhesion Poor adhesion on over-coating Coating discoloration over time Poor gloss retention
3
Q
- Runs, sags, and wrinkles may be caused by:
A
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
4
Q
- _________ is a powdery, friable layer on the surface of a coating that is most common with epoxy coatings.
A
Chalking
5
Q
Cratering may be caused by:
A
Air trapped in the wet film
Improper mixing procedures
6
Q
- Voids are typically caused by:
A
When a mixer is run too fast
7
Q
- Pinholes are:
A
Very small holes in a coating, typically caused by painting over an inorganic zinc coating or sprayed metal coating.
8
Q
- A common cause of blistering is:
A
Entrapped solvents in film High humidity Excessive wind surface drying Incorrect application temperatures Dirt, Dust, Grease, Retained Solvents
9
Q
- Cracking of a coating is noted:
A
When the crack extends to the substrate
10
Q
- Checking can be described as:
A
Fine cracks in the surface of a coating that don’t extend through to the substrate
11
Q
- Adhesion failures may be caused by:
A
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
12
Q
- What is Cissing? Or fisheyes or crawling
A
A term for surface breaks in the film that reveal the substrate resulting from grease or oil residue on substrate
