How Will a Plane Best Fit In the Paint Booth?
Due to the nature of the airflow, crossdraft paint booths can accommodate any plane that fits into the booth. A crossdraft booth requires only minimal clearance around the ends and wingtips to move people, materials and personnel lifts.
On the other hand, downdraft booths are designed for a specific type and size of aircraft. The exhaust pit is installed in the shadow of the plane. Airflow will be optimal if all aircraft used in the booth are nearly the same size and have a wing that angles either backward or forward, rather than sideways. If planes are of varying sizes and wing shapes, airflow will be ideal for only a handful of planes.
How Can I Minimize Overspray?
In a crossdraft paint booth, the plane should be positioned so that air flows from the nose to tail. Due to the size of an aircraft booth, as overspray is pulled horizontally across the booth into the filtered plenum at the back of the booth, some of it will drop onto the floor or aircraft. It is important to cover sections of the aircraft downstream of the spray guns to prevent blemishes. It is also best to work high to low and front to back in crossdraft booths.
Downdraft paint booths are heralded as best for painting cars, trucks, buses, railcars and farm equipment — anything that does not require the bottom to be painted. When it comes to planes, the underside accounts for about 50 percent of a plane and is just as important of a side to paint. Painting the underside can be a challenge though, as it places the painter between the paint gun and the floor. In a downdraft booth, paint overspray is pulled away from the plane and toward the floor filters. As air rolls over the wing and fuselage, it can be difficult to control overspray, so it is also best to work high to low in downdraft booths.
How Do I Change the Filters?
A crossdraft spray booth allows for all filter stages to be in one location, and the exhaust filters can be changed from outside the filter house. The only tool needed is a rolling platform or personnel lift to reach the highest filters.
In a downdraft booth, the first stage of filters are located in the floor trench beneath the grating. Sometimes, grates must be lifted off to access the filters. If the grating is rated for the load of the plane, a hoist might be needed to remove the grating due to its weight. The filters in the downdraft filter house — two stages — are handled the same way as the filters in a crossdraft filter house.
To ease the burden of filter changes, a viable option is an automatic filter-changing system, using rollers and a support bed. Even so, filters must be changed frequently enough to minimize the accumulation of paint residue. Intake filters also need to be replaced in both styles of booths.
How Good Is the Paint Quality?
Without a doubt, a paint booth will offer a better paint job than painting a plane in a hangar with the door open. Controlling the airflow and cleanliness of the air is essential to obtaining a blemish-free appearance.
Downdraft booths are recognized as top-of-the-line for high-quality finishing applications, even with a product as large as an airplane. But high-quality finishes also can be achieved in crossdraft booths.
Painting between 70 and 75 degrees, with humidity between 40 and 60 percent, is ideal for most aircraft. Stealth coatings, in particular, require a narrow temperature range and specific humidity level to adhere properly. When humidity levels are controlled, the booth can provide big dividends.
Due to the highly sensitive electronics in aircraft, they must be cured at a lower temperature than vehicles or industrial equipment — typically no more than 120 degrees. If removed from an aircraft, parts and components may be cured at temperatures that reach 160 to 180 degrees.