Automotive Body Repair & Painting NC II cheat sheet

Hazard communication uses GHS pictograms; the flame pictogram marks flammable liquids such as basecoat reducers and solvent cleaners.

Personal protective equipment for painting: supplied-air or cartridge respirator with organic-vapor and particulate filters, nitrile gloves, splash goggles, and paint suit.

Isocyanate hardeners can cause asthma sensitization; exposure limits are set per SDS Section 8 and must not be exceeded.

A Safety Data Sheet has 16 sections; Sections 2 (hazards), 4 (first aid), 7 (handling), and 8 (exposure controls) are the most consulted in a body shop.

Lockout/tagout requires the energy source be isolated, locked, and tagged before servicing spray booths, compressors, or panel-pulling equipment.

Fire extinguisher classes: A ordinary combustibles, B flammable liquids, C energized electrical; solvent fires require B or ABC rated units.

A job card or repair order is the controlling communication document; any deviation from it must be documented and approved in writing.

Reporting chain rule: injuries, near misses, and equipment damage are reported to the supervisor immediately, then recorded in the incident log.

Feeler gauge measures gap clearance; a typical panel gap specification is 4-6 mm and is checked with a gauge or gap tool.

Vernier caliper least count = 0.02 mm on a 0.5 mm main-scale division with 50 vernier divisions; reading = main scale + (vernier line × 0.02 mm).

Micrometer reading = barrel reading + (thimble division × least count); a 0-25 mm metric micrometer typically reads to 0.01 mm.

Torque wrench accuracy is maintained only within its stated range (commonly 20-100% of full scale); store it at the lowest setting.

A sanding block with a flexible or semi-rigid pad keeps contours flat; a hard block is used for blocking primers and a soft pad for curved panels.

Disc grinder safety: guard in place, correct RPM-rated disc, no gloves near rotating disc, and face shield plus hearing protection.

A stud welder/dent puller uses capacitive discharge; the ground clamp must contact bare metal on the same panel being pulled.

Angle grinder cutting discs must never be used for grinding and vice versa; disc type and RPM rating must match the tool nameplate.

Damage classification: direct damage is at the impact point; indirect damage is transferred through the structure (buckles, misaligned gaps).

A paint thickness gauge reading above roughly 300-400 µm indicates prior refinish or body filler that must be stripped before further repair.

Steel body panels are typically 0.6-0.9 mm thick; high-strength and ultra-high-strength steels require heat-free repair per OEM position statements.

Body filler is applied in thin coats (about 3-6 mm maximum per application) over a properly abraded, clean, bare-metal surface.

Hammer and dolly technique: off-dolly stretches and raises metal, on-dolly planishes and flattens; work from the outside of the dent inward.

Heat shrinking uses a torch or shrinking disc; steel is heated to a dull red (approximately 650-700 °C) then quenched with a damp cloth.

Galvanized and aluminum panels require dedicated tools and abrasives to prevent cross-contamination and galvanic corrosion.

A pick hammer and spoon are used for roughing out; a slapping file or body file reveals high and low spots during finishing.

Panel gap and flushness are checked before and after replacement; unequal gaps indicate structural movement rather than a simple bolt-on fault.

Spot welds are removed with a spot-weld drill (8 mm typical) or a belt sander; count and replace the same number of welds at the same locations.

Squeeze-type resistance spot welding is the OEM-preferred joining method for structural steel; MIG brazing is used on high-strength and galvanized steels where heat input must be limited.

Sectioning must follow OEM procedures: sectioning location, backing plate or insert requirement, and weld type are specified per vehicle.

Structural straightening uses a pulling system with a measuring system (universal or dedicated jig) to verify datum and control points.

Adhesives for panel bonding require a specified squeeze-out bead, clamp time, and cure time; the bond line must be continuous where specified.

Corrosion protection is restored after welding: zinc-rich primer on weld zones, cavity wax inside enclosed sections, and seam sealer at joints.

Aluminum structural repair uses dedicated rivets and adhesive bonding; steel rivets in aluminum cause galvanic corrosion.

Abrasive grit progression: 80-180 for stripping and shaping filler, 240-400 for primer sanding, 600-800 for blending and pre-clear scuffing.

Surface cleaning order: wash with detergent, then use a wax and grease remover with two clean cloths - one wet, one dry - before sanding.

Masking tape and paper must be rated for the booth temperature; edges are pressed down and gaps sealed to prevent overspray and hard edges.

Mixing ratio is by volume per the product data sheet; use a mixing cup with graduated ratio scales and stir thoroughly, then allow induction time if specified.

Pot life begins at mixing; material must be used within the stated pot life and never topped up with fresh material.

Reducer choice depends on booth temperature: fast reducer for cool conditions, slow reducer for hot conditions, to control flow and solvent pop.

Primer surfacer is applied over sanded filler and bare metal; an epoxy primer is used for bare steel and aluminum as a corrosion barrier.

Sealer is applied before basecoat to ensure uniform color holdout and to prevent bleeding from underlying repair areas.

Spray gun setup: fluid tip 1.3-1.4 mm for basecoat and clearcoat, 1.6-1.8 mm for primer surfacer and high-build products.

Typical spray pressure is 2-2.5 bar (about 30-35 psi) at the gun inlet for HVLP; atomization and pattern are adjusted before the vehicle.

Gun distance is 15-20 cm with 50% overlap per pass; a closer distance causes runs and mottling, a farther distance causes dry spray.

Defect causes: orange peel from too-fast thinner or low pressure; runs from heavy coats or too-slow reducer; solvent pop from too little flash time.

Blending basecoat requires a blender or melt-in agent at the edge, with the blend panel cleared to a natural break line.

Clearcoat film build is measured with a gauge; insufficient clearcoat reduces UV protection and gloss retention.

Dust nibs are removed by sanding with 1200-1500 grit then polishing with a compound and foam pad at low speed.

Booth conditions: about 20-25 °C and filtered downdraft airflow; flash-off time between coats follows the product data sheet.

Reassembly sequence reverses disassembly; fasteners are torqued to specification and one-time-use fasteners are replaced rather than reused.

Pre-delivery inspection checks panel gaps, flushness, paint match under daylight, trim fit, electrical function, and water leak test.

Paint match is evaluated under a color-corrected light or daylight, never under sodium or mixed shop lighting.

A quality checklist includes runs, sags, dirt, orange peel, fish eyes, color mismatch, overspray on glass and trim, and missing clips.

Daily housekeeping: empty and close solvent waste containers, clean gun immediately after use, and wipe booth surfaces to control dirt.

Compressed air lines require a filter-regulator-lubricator and moisture trap; water in the line causes fish eyes in the finish.

Tools are returned to marked locations and damaged tools are tagged out; missing or damaged PPE is replaced before work resumes.

Waste segregation: solvent-contaminated rags, waste paint, and used filters are hazardous waste and are kept separate from general refuse.

Paint products have a shelf life (commonly 1-3 years for basecoat and hardeners); expired hardeners cause poor cure and loss of gloss.

Hardeners are matched to the product line; mixing brands or using the wrong hardener speed causes curing, gloss, or adhesion failure.

Solvent waste is stored in labeled, closed, grounded metal containers; static discharge can ignite flammable vapors.

Spray booth filters are replaced per pressure-drop or schedule; loaded filters reduce airflow and cause dirt and poor drying.

Aerosol and solvent containers are emptied fully before disposal per local regulations; never puncture or incinerate pressurized cans.

Consumables inventory uses first-in, first-out rotation so older stock is used before shelf life expires.

Waste classification: waste paint, solvent, and contaminated absorbent are hazardous; masking paper and clean cardboard are general waste.

VOC content is stated on the SDS and product data sheet; low-VOC and waterborne products reduce emissions but still require PPE.