chapter 14 coatings failurs

Question 1

the mechanism of chalking is essentially one in which the coating _______ tends to gradually _______, leaving the surface covered with pigments that had been held on the surface by the ________.

Answer 1

binder
disintegrate
binder

Question 2

______ or ______ of a coating is due to the exposure of a coating to the ________ rays of the sun and the action of the __________ on the organic binder.

Answer 2

powdering
chalking
actinic
radiation

Question 3

_______ have a positive influence on chalking, as they tend to reduce the chalking by _______ the resin from the sun’s rays

Answer 3

pigments

shielding

Question 4

Identify an ASTM standard that provides a method of determining the degree of chalking

Answer 4

ASTM standard D4214

Question 5

_______ is essentially a wearing away of the coating surface in a _______ manner similar to the chalking mechanism.

Answer 5

Erosion

gradual

Question 6

_______ is small breaks in a coating surface that forms as a coating ages and does not ______ the full depth of the coating.

Answer 6

Checking

penetrate

Question 7

_______ is the shrinkage of the surface while at the same time the _____ of the coating does not change in the same way.

Answer 7

Alligatoring

body

Question 8

___________ results from stresses on the _______, while cracking is caused by stresses ______ the film and ______ the film and the substrate.

Answer 8

checking
surface
throughtou
between

Question 9

Cracking occurs as a coating ages: as it is subject to _____ and _____, ____ and _____, _____, and _____ of moisture, etc.

Answer 9

expansion and contraction
wetting and drying
absorption and desorption

Question 10

Reinforcing pigments, which are _____ or _______, aid materially in reinforcing the coating against cracking action.

Answer 10

Fibrous or acicular

Question 11

ASTM Standard _______ can be used to evaluate extent of cracking.

Answer 11

D661-81

Question 12

___ ______ occurs when highly filled coatings area applied rather heavily.

Answer 12

Mud cracking

Question 13

______ is the result of the ______ of a coating where the _____ of the coating expands more rapidly during the drying period than the ______ of the coating.

Answer 13

Wrinkling
swelling
surface
body

Question 14

Some driers are used to speed the _____ cure and others are used as ______-______ materials

Answer 14

Surface

through- drying

Question 15

_____ materials are examples of surface driers; _____ and _____ compounds are classified as through driers.

Answer 15

Cobalt

zinc and lead

Question 16

Poly-amide curing agents are susceptible to biological failure, while _____ ____ curing agents have excellent resistance to sewage conditions.

Answer 16

Amine type

Question 17

Fungus growth can be largely eliminated by the use of _____ _____ as part of the pigmentation, along with the addition of _____ , _____ or a combination of all three.

Answer 17

Zinc Oxide
Fungicides
Bactericides

Question 18

Inorganic zinc coatings are highly filled with metallic zinc, and the _____ to binder ration is very high, so when drying is ____, fine surface ____ can occur.

Answer 18

pigment
rapid
checking

Question 19

Chalking remedy

Answer 19

coating formulated with radiation resistant resins (acrylic) and non catalytic, non chalking pigments.

Question 20

Alligatoring remedy

Answer 20

Apply thin coats, dry thoruoughly before additional coats, never apply hard top coats (epoxy) over soft under coat (asphalt).

Question 21

Mud Cracking remedy

Answer 21

use coatings with strong adhesions, apply under proper drying conditions, prevent sags, puddles, or areas of excess thickness.

Question 22

Biological failure remedy

Answer 22

select oil-based coating which contain fungicides or bactericides.

Question 23

Wrinkling

Answer 23

choose coatings with even, thorough drying, charctristics

apply evenly avoid excess thickness.

Question 24

pinpoint rusting remedy

Answer 24

apply maintenance coat at first sign of failure.

remove coating and reapply more satisfactory zinc coating.

Question 25

erosion remedy

Answer 25

select chalk resistant coating with good flow out to a smooth film

Question 26

three types of contaminants in steel after blasting

Answer 26

rusting chlorides sulfides

Question 27

previously used steel failure

Answer 27

retention of minute amounts of corrosion product or contaminant along grain boundaries of the steel.

Question 28

galvanized steel failure

Answer 28

formation of zinc salts (oxides, sulfide, zinc soap)

Question 29

copper failure

Answer 29

smooth copper oxide surface. No physical adhesions

Question 30

wood failure

Answer 30

expansion and contraction due to humidity soft porous grain

Question 31

concrete failure

Answer 31

chemical reactivity and moisture content

Question 32

coating failures are more probable when _____ are used than when the same coating is applied over a _____ abrasive blasted surface.

Answer 32

inhibitors | dry

Question 33

retained solvents may cause ______ and ___ adhesion to the substrate because the underlying coating is ____ and the ___ ___ are close to the substrate.

Answer 33

blistering and low porous retained solvents

Question 34

regardless of their size and description, _____ are essentially discontinuity in a coating.

Answer 34

Holidays

Question 35

______ is generally the result of poor gun adjustment, or application of the coating at too ____ a distnce from the surface, and not applying an even _____ film to the surface.

Answer 35

over-spray great wet

Question 36

For the most part, ______ result from ______ application of a coating, with ____ being blown into the surface during the application.

Answer 36

pinholes heavy air

Question 37

cratering (or ________ or ______) may be either an ______ problem, a _____ problem, or _______.

Answer 37

bug-eying or crawling application material or both

Question 38

Much catering is due to _______ on the surface or that falls into the wet coating.

Answer 38

contamination

Question 39

runs, sags, and curtains failures

Answer 39

lack of care in application

Question 40

Brush mark failure

Answer 40

pooor workmanship

Question 41

overspray failure

Answer 41

uneven spray passes with gun too far from the surface

Question 42

pinhole failures

Answer 42

spray gun to close to surface with air bubbles being forced into coating

Question 43

holidays failure

Answer 43

poor, inconsistent application

Question 44

cratering failure

Answer 44

improper solvent mixture

Question 45

two types of blisters

Answer 45

coating separating from substrate or | between coats

Question 46

Where there is solvent retention and the coated surface _____ in temperature, the solvent itself may create a sufficient _____ pressure to cause blisters to form in the coating.

Answer 46

changes | vapor

Question 47

cathodic protection blisters in coatings are caused by _____ gas being formed on the metal underneath the coating is sufficient volume so the the _____ ____ pressure pushes the coating off the surface.

Answer 47

hydrogen | hydrogen vapor

Question 48

peeling can be caused by _____ surface preparation, _____ between coats, or when the coating thickness is too _______.

Answer 48

poor contamination great

Question 49

_______ is much like peeling except that the flaked coating is usually _____ and _____ and tends to pull itself away from the substrate.

Answer 49

Flaking | hard and brittle

Question 50

Inter-coat _________ occurs most often where repair or maintenance coatings are being applied over existing coatings that are _____, have ______ embedded in the surface, or have oxidized or cured to the point of complete _______ and ________.

Answer 50

delamination chalky dirt insolubility and impenetrability

Question 51

When coal tar epoxy coatings are exposed to ______, that will catylyze the curing of the surface to the point where additional coats will not ______ ______.

Answer 51

sunlight | adhere properly

Question 52

__________ of a coating is the action of rust under the coating, usually forming around a small _____ in the coating.

Answer 52

undercutting | break

Question 53

A coating applied over ____ ____ is susceptible to undercutting, since once a break in the coating occurs: corrosion can begin between the ____-____ _____ and the steel

Answer 53

Mil scale | mil scale surface

Question 54

Reverse impact is ____ ____ difficult for a coating to resist than _____ _____ .

Answer 54

much more | direct impact

Question 55

Most coatings are _____ for faying surfaces because of the fact that the coefficient of friction is not _____ for the bonding of the joint.

Answer 55

unsuitable | sufficient