1. Chapter 18 Paint Problems and Final Detailing

2. Objectives List and explain the most common paint/refinish problems Repair common finish problems Use a sanding block Wet sand to remove minor finish problems Hand and machine compound a finish Properly final detail a vehicle

3. Introduction After painting vehicle and removing masking materials, check your work quality Ideally vehicle can be released to customer after a minor cleanup Sometimes small imperfections in paint film must be corrected Rarely, you may have to solve major paint problems on existing or freshly painted surfaces

4. Surface Imperfections Steps for correcting surface imperfections: –Examining finish for imperfections –Correcting imperfection –Finesse finishing –Final detailing There are a number of defects in repair that must be corrected before vehicle is released –Runs, sags, orange peel, dirt, dust, overspray

5. Surface Finish Measurements Good panel repair should not be rough, wavy or have surface flaws Surface roughness is a measurement of paint film or other surface smoothness in a limited area, due to improper mixing or spraying Surface waviness is a measurement of an area’s general levelness, due to improper sanding, or blocking of plastic filler or primer Body technician makes extra work for painting technician if filling work is poor

6. Paint Problems Paint problems include a wide range of troubles found before or after painting Acid and alkali spotting cause an obvious discoloration of the surface Wash vehicle with detergent and water, followed by a vinegar bath Wet sand for minor spotting If spots have absorbed deep into finish, or down to the metal, sand and refinish

7. Bleeding Bleeding is a discoloration of new paint after refinishing –Results when solvent in new finish penetrates materials underneath –To remedy, remove all colorcoats and refinish You can also allow surface to cure, apply bleeder sealer and recoat To prevent bleeding, apply bleeder sealer over suspected bleeder colors before spraying

8. Blistering Blistering shows up as small, swelled areas on finish Lack of gloss if blisters are small, and broken- edged craters if blisters have burst Blistering is usually caused by rust under the surface, or by spraying over oil or grease Blistering can also be caused by prolonged exposure of surface to high humidity Sand and refinish blistered areas, and frequently drain air lines of water

9. Blushing Blushing makes the finish turn “milky” Caused by fast solvents/reducers in high humidity or condensation on vehicle To remedy blushing, add retarder to solvent reducer and respray –May also have to sand and refinish To prevent blushing, keep material and surface to be sprayed at room temperature

10. Dirt in Finish Dirt in finish is caused by foreign particles dried in paint film due to improper cleaning Dirt can come from work area or dirty spray gun To correct light dirt, rub out finish with a polishing compound If dirt is deep in the finish, sand and compound to restore gloss Metallic finishes may show mottling with this treatment and require additional colorcoats

11. Fisheyes Fisheyes are a problem with separation of wet film, and small indentations will form in wet film Fisheyes are usually caused by improper cleaning of old surface –May be due to spraying over finishes that contain silicone Wash off new finish while it is still wet and respray A fisheye preventer can be added to paint

12. Mottling Mottling is a streaking of the color, usually with metallic finishes caused by excessive wetting To remedy mottling of freshly applied finish, back spray gun away when spraying Increase air pressure for final coat, and avoid overreduction On a dried finish, scuff down the surface and apply additional color To prevent mottling, avoid excessive wetting or heavy film buildup in local areas

13. Orange Peel Orange peel is paint roughness that looks like tiny dents in the finish Commonly caused by underreduction or an improper solvent/reducer To fix this while you are painting, thin or reduce final coat to its maximum limit and apply last coat wet Rub surface with a mild polishing compound You may have to sand and refinish

14. Peeling Peeling is a separation of surface film from subsurface Caused by improper surface preparation, or incompatibility of one coat to another To repair peeling, you must remove peeling finish completely, and refinish surface Pin holes are noticeable air bubbles raising surface film caused by too much hardener Sand thoroughly and recoat with a glaze coat of body filler or putty

15. Plastic Bleed-Through Plastic bleedthrough is a discoloration of color due to chemicals from body filler May be caused by too much hardener or by applying paint before body filler is cured Allow topcoat to cure and refinish Rust under finish causes finish to peel or blister Seal off moisture from inner part of panels, sand down to bare metal, and spray with a rust preventative before refinishing

16. Figure 18-13. Rust under a finish is due to improper surface preparation.

17. Runs Runs occur when gravity produces a mass slippage of an overwet, thick film Runs are caused by overreduction with low air pressure, extra slow-drying solvents/reducers Runs can also be caused by spraying on a cold surface, improper cleaning, too many coats Allow finish to cure, then sand and refinish If run is only in clearcoat, you can often wet sand and level run without refinishing

18. Sag A sag is a partial slipping down of the surface film created by a film that is too heavy To fix a sag, sand or wash it off and refinish In “primecoat show-through” the color of the primecoat shows through paint Caused by insufficient colorcoats or repeated compounding, or by not having uniform color under paint To fix show-through, sand and refinish

19. Water Spotting Water spotting is a dulling of gloss in spots, due to water drying on a finish that is partly wet To repair water spots try to wet sand and polish, but you may have to sand and refinish Wet spots are off-colored or slow-drying spots of various sizes, usually due to improper cleaning Sand or wash surface off thoroughly and refinish To prevent this, clean surface with wax and grease remover and allow primecoats to dry

20. Wrinkling Wrinkling is severe puckering of film that appears like the skin of a prune To fix wrinkling, break open top surface by sanding, and allow it to dry thoroughly Remove finish and refinish surface Metal dust damage occurs when metallic particles from industrial fallout settle on paint Metal dust damage looks like small brown or black specks, or a prickly protrusion in film

21. (A) Metal dust etched into the clearcoat can be felt with a hand or rag. (B) After treatment, this damage can be repaired by wet sanding the clearcoat and compounding. Figure 18-18. Metal dust fallout can etch into the finish.

22. Metal Dust Damage Treat metal dust damage with mild oxalic acid solution to dissolve the rust If solution does not dislodge all particles, wet sand affected area Acid rain damage varies depending on chemicals in the fallout Minor acid rain damage produces shallow craters, dulling, fading, and chalking Neutralize acid with a solution of 1 tablespoon of baking soda per quart of water

23. (B) Major acid rain damage is too deep and the area must be refinished. Figure 18-19. Acid rain damage can also “eat” into the finish. (A) With minor acid rain damage, the clearcoat is not penetrated. Wet sanding and buffing will usually fix the damage.

24. Acid Rain Damage Major acid rain damage is severe chemical etching that has eaten through the paint To repair, strip all finish from damaged areas and refinish Sand scratches result from final sanding with incorrect sandpaper and not allowing materials to dry completely before painting/refinishing You may be able to wet sand and machine compound area, or you will have to resand and refinish area

25. Final Detailing The object of final detailing is to locate and correct any defect If whole vehicle is not refinished, take time to touch-up chips in finish Surface protrusion is a particle of paint or debris sticking out of film after refinishing Cut off protrusion, smooth with a finesse sanding block Finish with extra-fine rubbing compound

26. Final Detailing (continued) Finesse sanding can be used to level the protrusion to the surrounding film Wet sanding smoothes paint surface on larger areas Wet sanding is normally done with a backing pad or rubber sanding block, in a circular motion Rubbing compounds generally contain coarser grit than polishes Hand compounding uses a cloth with back-and- forth strokes, and medium-to-hard pressure

27. Machine Compounding Machine compounds are often water-based to disperse the abrasive using a power buffer Burn-through occurs when pad removes too much paint on a surface Compound has a tendency to dry out, so do a small area at a time Polishing uses a very fine compound to bring paint surface up to full gloss Use an orbital action machine for final polishing to prevent swirl marks

28. Figure 18-24. A foam pad is softer than a wool pad and will reduce swirl marks in the finish. It is often used after a wool pad. Use finer machine compound with a foam pad.

29. Sponge Buffing Pads Sponge pads for buffing tend to be more user friendly and less apt to damage the new finish Softer buffing action leaves finish with a more natural-looking gloss Sponge pad transmits heat back into surface If surface overheats, compound will gum up and collect in a glue-like mass

30. Get Ready Interior of the vehicle should be cleaner than when customer brought it in Vacuum interior carefully and if dusty, clean and treat vinyl surface with a conditioner Clean stubborn stains with a recommended cleaning solution Remove any overspray on vehicle, and clean tires and wheels Inspect vehicle with a careful eye for details

31. Figure 18-25. Make sure the vehicle is perfectly clean before releasing it to the customer. First impressions of the vehicle are very important.

32. Caring for New Finish Avoid car commercial car washes for 1-3 months Hand wash using only water and a soft sponge for the first month, dry with cotton towels only Avoid waxing and polishing for three months –After three months wax designed for basecoat- clearcoat finishes Avoid scraping ice and snow near newly refinished surfaces Flush gas, oil or fluid spills with water as soon as possible for the first month, do not wipe them off

33. Summary Some of the most common paint problems include pinholes, mottling, runs and sags Steps for correcting surface imperfections: examining the finish for imperfections, finesse sanding, buffing and final detailing Objective in final detailing is to locate and correct any defect that may cause customer complaints Four steps: sanding and filing, compounding, machine and hand glazing