Automotive Refinish Booths for Collision Shops

Downdraft or Semi-Downdraft for Collision Work

Full downdraft booths bring air in through the ceiling and pull it down past the vehicle into a floor pit or raised basement. Air travels the shortest distance from painter to exhaust, which keeps overspray off the rest of the car and generally gives the cleanest finish. The tradeoff is a pit or a raised floor with a ramp. Semi-downdraft booths bring air in from the ceiling at the front and exhaust at the rear wall, so air moves down and back along the car. They avoid the pit and are easier to fit in leased buildings, but overspray travels farther along the vehicle. Side downdraft booths exhaust low along the side walls and are another middle-ground option. Shops focused on high volume and premium finish often favor full downdraft, while shops with building limits often choose semi or side downdraft.

• Full downdraft: cleanest airflow, needs pit or basement
• Semi-downdraft: no pit, air travels the length of the car
• Side downdraft: exhaust at the walls, no pit, more even than rear exhaust

Bake Cycles and the Heating Package

Most refinish booths double as a bake chamber. After spraying, the booth switches to a recirculating mode, raises the cabin temperature with the air make-up heater, holds for the bake portion of the cycle, then cools down before the car comes out. The heater, dampers and controls all have to work together, and the burner has to be sized for the booth and the climate. Gas supply, venting and control wiring are installed alongside the booth. Some shops add curing accelerators such as infrared arrays or air movers to speed flash and cure for waterborne coatings.

Cycle Time and Where It Is Lost

Booth throughput depends on more than the bake. Time is lost bringing cars in and out, masking and prep work happening inside the booth, waiting on color, and slow heat-up or cool-down. A well-planned shop keeps the booth for spraying and baking only. That means prep stations handle sanding, priming and masking, the mix room has color ready, and cars are staged right outside the doors. Controls that recall saved cycles and alert when filters need changing also help keep the booth productive.

• Do prep and masking outside the booth whenever possible
• Have mixed color ready before the car enters
• Watch filter loading, which slows airflow and heat-up
• Plan staging space at the booth doors

Mix Room and Prep Station Flow

The mix room needs to be close enough to the booth that painters do not walk across the shop with coatings, but it must be a ventilated and properly classified space of its own. Prep stations, often with their own ventilation and curtains, should sit upstream so cars move prep to booth to reassembly without doubling back. Compressed air for prep, the mix room and the booth should be clean and dry, with drops and regulators where painters actually work. Lighting in prep stations should be good enough to catch defects before the car reaches the booth.

Installation Considerations in an Existing Shop

Installing a refinish booth in a working shop means coordinating concrete work for a pit if one is used, roof or wall penetrations for exhaust and intake, gas and electrical service, and fire protection. The booth needs clearances for service access to the air make-up unit, filters and controls. Planning the install around shop production, and getting permits and fire code review lined up early, keeps the shop painting during the transition. Before quoting, an installer will want to see the floor where the booth will sit, the route for the exhaust stack, the location of the gas meter and electrical panel, and the path cars take from the body floor to the booth door. Ceiling height matters as well, since the intake plenum and air make-up unit need room above or beside the cabin.