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Finishing Academy Paint Booth Training

Choose one of these Aerospace Refinish Training Modules:


1.1 Introduction

1.2 Crossdraft

1.3 Downdraft

1.4 Airflow

1.5 Filter Replacement

1.6 Temperature and Humidity - Controlled Booths

1.7 Equipment

1.8 Fire Protection

1.9 Conclusion

1.2 Crossdraft


The most important element of any professional finishing program is the painter. Their skill and touch are often the difference between an indifferent paint job and a high quality paint job. In the end it is the finish that is the objective, not the airflow patterns in the booth. Having said that, if we took the approach that we had the best painters on earth, what would be the ideal airflow pattern in a paint booth? Would it be cross-draft or down-draft? Airplanes are difficult items to design a paint booth for. The aerodynamic shape of an airplane tends to cause disruptions in airflow. Many items that are painted in paint booths like buses and trucks have enough volume that they significantly affect the remaining volume of the booth. That is not true with airplanes. In a crossdraft booth, the head-on silhouette is a very small percentage of the booth cross sectional area. In the downdraft mode, the plane ‘shadow’ area could result in reduced airflow underneath the aircraft.

Description of Booth Types

There have been many discussions regarding the perfect paint booth for painting aircraft. Many people prefer crossdraft booths while still others make an argument for downdraft booths. Here we explore the issues involved with each type of booth.


Crossdraft booths have a filtration section on one end drawing air through the booth. This exhaust filter bank may contain three stages of filtration in accordance with NESHAP (National Environmental Standard for Hazardous Air Pollutants) if there are paints that contain metals such as Hexavalent Chromates. All three stages may be placed in a single filter rack. Exhaust fans are placed on the clean air side of this filter chamber. Air is drawn through the booth, enters the filter chamber, and the filtered air is exhausted outside of the paint booth.

The air entering into the booth may be either forced draft or natural. In the natural draft style, the supply air is drawn through the filtered hanger doors by the exhaust plenum on the opposite end of the booth. Once through the exhaust plenum, the filtered air is then exhausted to the outside of the booth. The advantage of this style booth is costs; however, the disadvantage is that there is no ability to control the temperature or humidity within the booth.

In forced draft style, the air is supplied to the booth from an air make-up unit at the intake plenum This requires a plenum in the filtered front of the booth to receive the forced draft air and balance it before entering the booth. This plenum (often a plenum door) is usually filtered and allows for very clean supply air to the booth. Air is then drawn through the booth into the exhaust plenum where it is filtered and exhausted outside the booth. The advantage of this design is that the intake air make-up unit can include heating, cooling, and humidification to provide temperature and humidity control within the paint booth. This booth design is typically designed to run the booth at a slight negative pressure which is advantageous in preventing any paint fumes from existing the booth.

Advantages and Disadvantages

The advantages of crossdraft paint booths are costs and flexibility. A crossdraft paint booth insert can be easily installed into an existing hangar. The floor is already in place and all that must be added is static grounding lugs. The concrete floor will carry the load of a plane, even fully loaded. On a ‘greenfield’ site, the building can be designed to support the structural load of the booth, other wise it can be independently supported from the floor. In either case, both types of inserts may be relocated to another facility.

The disadvantages to a crossdraft booth are the potential for there to be low air flow areas in spaces where the air is blocked by the aircraft structure.



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