Paint Defects

Question 1

Poor Adhesion - Clear Coat
Cause

Answer 1

1. Base coat too thick with little flash off time (still wet)
2. Wrong mixing ratio for clearcoat and activator
3. Inadequate sanding of the substrate

Question 2

Poor Adhesion - Clear Coat
Prevention

Answer 2

1. Allow base coat to flash off properly before clear
2. Check TDS for film thickness
3. Mix correct ratio of clear coat

Question 3

Poor Adhesion - Clear Coat
Remedy

Answer 3

1. Rework - Sand back affected area and prime if needed to seal the defect.

Question 4

Poor Adhesion - Plastic
Cause

Answer 4

1. Failure to remove mold-release agents
2. Improper cleaning/prep
3. Failure to use primer as a sealing coat (wet on wet)

Question 5

Poor Adhesion - Plastic
Prevention

Answer 5

1. Thoroughly clean substrate
2. Use primer with correct mixing ratio
3. Use suitable adhesion primer for the type of substrate being used.

Question 6

Poor Adhesion - Plastic
Remedy

Answer 6

1. Rework - Sand back affected area and all layers. 2k prime to seal if necessary.

Question 7

Poor Adhesion - Filler
Cause

Answer 7

1. Not sanded/prepared properly/cleaned
2. Surface temp too high
3. Not enough hardener

Question 8

Poor Adhesion - Filler
Prevention

Answer 8

1. Clean and prep with correct grit the filler takes.
2. Use correct mixing ratios and ensure hardener is mixed properly.

Question 9

Poor Adhesion - Filler
Remedy

Answer 9

1. Sanded back affected area to bare metal and start again.

Question 10

Bleeding

Answer 10

Original colour or the filler seeps through the topcoat and causes discolouration in clear coat.

Question 11

Bleeding - Causes

Answer 11

1. Pigments of original colour react with solvents in clear coat
2. Excess hardener in filler which is pulled up by the clear coat solvents.
3. UV sensitive hardener reacts to UV light being pulled to topcoat over time.

Question 12

Bleeding - Prevention

Answer 12

1. Apply a sealer coat (primer)
2. Use correct/recommended mixing ratio of filler and hardener
3. Use a dispensing machine for filler and hardener

Question 13

Bleeding - Remedy

Answer 13

1. Remove filler and rework repair
2. Sand back affected area and refinish

Question 14

Blistering - Causes

Answer 14

1.Water residue from wet sanding not evaporated
2. High booth humidity
3. Waterbased degreaser not cleaned away
4. Improper flash off times of base coat.
5. Water in airlines

Question 15

Blistering - Prevention

Answer 15

1. Blow and clean substrate properly before applying base coat
2. Use correct thinners/reducers for base coat
3. Allow base coat to flash off appropriately.
4. Drain compressor and clean regulators daily.

Question 16

Blistering - Remedy

Answer 16

Rework - Sand back affected area if necessary and re seal with primer.

Question 17

Chipping - Cause

Answer 17

Stones or other loose materials hitting panel.

Question 18

Chipping - Prevention

Answer 18

1. Use appropriate paint system for area regularly exposed to stones.
2. Use flexible primer
3. Activated base coat allows for more strength against further corrosion

Question 19

Chipping - Remedy

Answer 19

Sand back affected area (bare metal if rust) and seal with primer.

Question 20

Clear Coat Yellowing - Causes

Answer 20

1. Wrong Hardener used
2. Incorrect film thickness

Question 21

Clear Coat Yellowing - Prevention

Answer 21

1. Ensure hardener is stored correctly.
2. Follow TDS on film thickness
3. Use recommended activator

Question 22

Clear Coat Yellowing - Remedy

Answer 22

Completely dry and bake finish. Sand back clear coat and refinish.

Question 23

Cobwebbing - Cause

Answer 23

1. Use of cold paint
2. High viscosity
3. Use of cheap/incorrect thinner.
4. Too high spraying pressure

Question 24

Cobwebbing - Prevention

Answer 24

Apply at recommended air pressure and viscosity

Question 25

Cobwebbing - Remedy

Answer 25

Reduce air pressure and reduce viscosity

Question 26

Colour Mismatch - Cause

Answer 26

1. Incorrect Formula used
2. Variation to OEM Finish
3. Incorrect gun set up
4. Original finish has changed due to weathering
5. Incorrect application (too much base coat)
6. Paint not mixed thoroughly

Question 27

Colour Mismatch - Prevention

Answer 27

1. Check formulation and spray outs for any variations against vehicle.
2. Stir colours thoroughly
3. Use recommended spraying technique
4. Blend adjacent panels

Question 28

Colour Mismatch - Remedy

Answer 28

Sand back panels and adjacent panels for blending. Re-paint.

Question 29

Corrosion - Cause

Answer 29

1. Surface/bare metal contaminated with moisture/water
2. Paint removed by chips
3. No etch primer used.
4. Rust not completely removed

Question 30

Corrosion - Prevention

Answer 30

1. Treat metal with etch/wash primer
2. Repair all chips before rust develops
3. Clean vehicle thoroughly before painting
4. Remove residual water

Question 31

Corrosion - Remedy

Answer 31

1. Substrate to be sanded back down to bare metal and rust removed
2. Use an acid based etch on aluminium panels.

Question 32

Cracking - Causes

Answer 32

1. Fluctuations in temp can cause paint to crack.
2. Too high film thickness
3. Flexible primer not used
4. Incorrect mixture of materials for paint such as omitting thinner

Question 33

Cracking - Prevention

Answer 33

1. Allow clear coat to flash off.
2. Don’t apply too much paint in one coat.
3. Follow TDS

Question 34

Cracking - Remedy

Answer 34

Sand back affected areas (bare metal if needed) and refinish.