Chapter 20 - Coatings Defects

Question 0

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

Answer 0

Surface tackiness or greasiness
Incomplete curing
Poor adhesion 
Coating discoloration 
Poor gloss retention

Question 1

Failure of coatings to cure May be caused by:

Answer 1

Not adding enough curing agent, wrong curing agent or incorrect amount of it

Problem with material from the manufacturer

Environmental issues(too cold, hot, or humid)

Wrong or contaminated thinner(Solvent)

Question 2

Runs, sags, and wrinkles may be caused by:

Answer 2

Applying the coating too thick
Too much or the wrong thinner used
Surface too hot to apply the coating 
Application of coating at the end of its pot life
Wrong thixotrope used in manufacturing

Question 3

CHALKING

Answer 3

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

Question 4

Cratering can be caused by:

Answer 4

Air trapped in the coating and forming a bubble which then bursts

Air trapped in the coating during mixing if the proper procedures are not followed

Question 5

Vacules or voids are typically caused by:

Answer 5

Running the mixer too fast

Question 6

Pinholes are:

Answer 6

Very small holes in a coating typically caused by air or solvent trapped in porous film and escaping

Question 7

A common cause for blistering is

Answer 7

Surface contamination under the applied coating.

Question 8

Cracking of a coating is noted:

Answer 8

When the crack extends to the substrate

Question 9

Adhesion failures may be caused by:

Answer 9

Contamination on the surface
Wrong surface preparation specified
Failure to inspect surface preparation
Insufficient surface profile 
Exceeding the topcoat window
Application of incompatible coatings