Pre-spray safety preparation is the primary step to avoid operational risks and ensure personal safety, which needs to be implemented from three aspects: workspace, protective gear, and environment. First, select a suitable workspace: prioritize an enclosed and well-ventilated area (such as a garage equipped with industrial exhaust fans). Close irrelevant air vents in the space to prevent external dust from entering, and cover the floor and walls with plastic sheets to reduce paint mist adhesion and dust interference. Second, prepare complete protective gear: must wear professional gas masks capable of filtering organic vapors (to avoid inhaling harmful gases in paint mist), well-sealed goggles (to prevent paint mist from splashing into the eyes), and solvent-resistant nitrile gloves (to isolate direct contact between paint and skin). For extended operating hours, additional protective clothing can be worn to minimize clothing contamination. Finally, clean the surrounding environment: completely remove flammable and explosive items (such as gasoline, alcohol, lighters, power strips, etc.) from the workspace and within a 10-meter radius nearby. Check for open flames or high-temperature sources (such as heaters, water heaters) in the area to ensure no ignition risks exist, laying a solid safety foundation for subsequent spray painting operations.
Car body cleaning and pre-treatment are fundamental steps to ensure paint adhesion, requiring three sequential operations. First, thoroughly clean the car body with neutral car wash soap. Use a soft-bristle brush to clean dirt in gaps, rinse with a high-pressure water gun, and then dry the surface with a chamois cloth to avoid residual sand particles scratching the paint. Next, treat the entire vehicle with a dedicated degreaser. Focus on wiping grease-prone areas such as the edges of the engine compartment and door handle recesses—dip a clean cloth in the degreaser and wipe repeatedly until no grease remains, preventing grease from affecting paint adhesion. Finally, carefully inspect and mark defects: examine the car body under sufficient light, and use masking tape to mark problem areas like dents, scratches, and rust spots. This provides clear guidance for subsequent sanding and repair, ensuring no omissions in the pre-treatment process.
Old paint treatment and defect repair directly affect the flatness of the paint finish, and must follow the process of "sanding old paint → filling dents → fine leveling". First, treat the old paint in stages with sandpapers of different grits. Start with 800-grit coarse sandpaper to quickly remove the car body’s oxidation layer, cracked old paint, and stubborn stains, initially creating a rough base. Then switch to 1200-grit fine sandpaper for overall precision sanding, focusing on edges, corners, and joints, until the old paint layer thins evenly and the surface feels smooth to the touch. After sanding, use compressed air to blow away dust. Next, fill dent defects with car-specific putty: take an appropriate amount of putty and scrape it repeatedly along the direction of the dent, ensuring the gap is fully filled and the putty is slightly higher than the car body surface. Wait for the putty to fully dry (about 4-6 hours at room temperature). Finally, perform sanding for leveling: first use 1500-grit sandpaper to wet-sand the putty surface (adding water reduces dust and avoids scratches), gradually sanding the putty until it is flush with the car body. Then switch to 2000-grit fine sandpaper for refinement, until there are no scratches or height differences on the surface and no unevenness is felt when touching it—laying a smooth base for subsequent spray painting.
Masking protection for non-spray areas is key to preventing paint mist contamination and ensuring spray precision, requiring proper tools and standardized operation. First, prepare automotive-specific masking film (waterproof and impermeable) and high-temperature resistant masking tape (to avoid adhesive residue when removed). Start with glass surfaces—cover all vehicle glass with masking film, sealing edges tightly with tape to eliminate gaps. Next, protect tires and rims: slip large masking film over tires from the top, covering down to rim edges, then secure overlapping film with tape to prevent shifting. Finally, handle detailed parts like headlights, chrome trims, door handles, and fuel caps. Use narrow masking tape to precisely adhere along part edges, then cover with small pieces of masking film, ensuring full sealing of all unpainted areas. After masking, inspect thoroughly to avoid gaps that could let paint mist seep through.
Primer spraying is a core step to enhance paint adhesion and rust resistance, requiring precise control of three key points. First, strictly follow the primer mixing ratio. Mix primer with a dedicated thinner according to product instructions (a common ratio is 2:1, subject to specific product labeling), stir evenly, and filter through a 120-mesh screen to remove impurities, preventing particles from clogging the spray gun and affecting results. Second, correctly adjust spray gun parameters: set air pressure to 2-3bar, keep the nozzle 15-20cm perpendicular to the car body, and adjust fan width to 15-20cm to ensure uniform paint mist coverage. Finally, apply multiple thin coats in a specific order: follow the sequence of "roof → hood → body sides → front and rear bumpers → undercarriage." Each thin coat should overlap adjacent mist by 1/3, with 2-3 total coats. Wait 30-60 minutes between coats (at room temperature), and apply the next coat only when the previous one is dry to the touch. This ensures a uniform, run-free primer layer, laying a solid foundation for subsequent topcoat spraying.
Topcoat spraying is a key step determining the vehicle's appearance, requiring standardized procedures to ensure uniform color. First, accurately mix the topcoat according to the vehicle's original color code. Add a dedicated thinner in the specified ratio (usually 1:1, subject to product instructions), stir well, and filter through a 150-mesh screen to remove impurities that could affect finish smoothness. Second, strictly control spray gun operation: maintain a 15-20cm distance between the nozzle and the body, keep movement speed steady at 30-50cm/second, and ensure single-coat thickness evenly covers the primer without runs. Finally, apply multiple thin coats in the order of "edges first, then flat surfaces." The first coat is a light base layer; wait 10-15 minutes (until surface-dry) before applying the second coat, with up to 3 coats as needed. Each coat should overlap 1/3 of the previous area to ensure consistent color across the entire vehicle, with no unevenness or primer exposure—laying a solid color foundation for the subsequent clear coat.
Clear coat spraying is critical for enhancing paint finish gloss and durability, requiring strict adherence to three key requirements. First, ensure compatibility between clear coat and topcoat. Choose clear coats from the same brand or those explicitly labeled "universal" to avoid wrinkling or dulling caused by ingredient conflicts. Second, mix clear coat according to specifications: add hardener and thinner in proportions specified by the product (typically 2:1:0.5), stir thoroughly, let stand for 5-10 minutes to activate, and filter through a 150-mesh screen to remove impurities. Finally, control the number of coats and intervals: apply 2-3 coats generally—first a thin base coat, second an even coverage coat, and third an optional coat adjusted for desired gloss. Wait 15-20 minutes between coats (until surface-dry), maintain a 15-25cm distance between gun and body, and move steadily to avoid localized buildup, ensuring a smooth, flat clear coat that provides long-term protection and a mirror-like finish.
Post-spray finishing and maintenance is the final step to ensure long-lasting paint gloss, requiring careful step-by-step execution. First, allow the clear coat to fully dry—at least 24 hours at room temperature (or 12 hours in high-temperature environments) to prevent damage from premature contact. Second, carefully remove masking materials: peel off tape first, then masking film, using a utility knife to gently lift edges if needed, avoiding paint peeling during removal. Next, address minor imperfections: lightly wet-sand flaws like paint particles or orange peel with 2000+ grit sandpaper, then rinse and dry the surface. Finally, polish and wax: use medium-cut polish with a buffer at low speed for uniform gloss, follow with mirror polish for refinement, and apply long-lasting protective wax. After 15 minutes, buff with a clean towel to enhance paint hardness and stain resistance, completing the final maintenance of the full vehicle spray.