Paint is an integral part of an aircraft. Aircraft painting protects the airframe’s integrity and influences the airplane’s weight. When an aircraft is painted properly, its exposed surfaces have greater resistance to dirt and corrosion, and oil doesn’t stick to the surface quickly. Hence, it’s easier to maintain and clean the aircraft.
However, there are certain issues that may arise during the painting process of any object. These issues are particularly troublesome and visible on aircraft surfaces. Here we have discussed some of the common problems encountered during aircraft painting and ways to address them.
Aircraft Painting Problems – Causes and Solutions
1. Poor Adhesion
The causes of poor adhesion include:
- Improper preparation and cleaning of the aircraft surface that needs to be finished
- Incompatibility of the primer with the topcoat
- Application of wrong primer
- Improper mixing of the materials
- Selecting a reducer of wrong grade or improper thinning of coating material
- Contamination of air supply and/or spray equipment
Correcting poor adhesion calls for removing the finish completely, determining and rectifying the cause, and refinishing the affected area completely.
The milky dull haze appearing in paint finish is blushing. This trouble arises when moisture gets trapped in paint. Blushing is formed when the solvents evaporate quickly from the sprayed coat, leading to a temperature drop that condenses water in the air. Usually, it occurs when the humidity level is more than 80%. There may be some other causes too that include:
- Extremely high air pressure at spray gun
- Use of improper reducer (fast drying)
- Improper temperature (above 95 °F or below 60 °F)
If you notice blushing during painting, you can add a slow-drying reducer to your paint mixture and respray the area. In case you find blushing after drying of the finish, you need to sand down the area and repaint it.
Pinholes are groups of holes or tiny holes occurring in the finish surface due to trapped moisture, air or solvents. Examples of causes include:
- Using an improper reducer or thinner, either too slow that causes solvents to be trapped by subsequent topcoats or too fast that involves quick drying of the surface and trapping of solvents
- Poor techniques of spraying that lead to excessively wet or heavy paint coats that tend to trap solvent or moisture under the finish
- Contaminants in air lines or the paint
If you notice pinholes occurring during aircraft painting, you need to evaluate the painting technique and equipment before continuing. On drying, the surface should be sanded smooth and then repainted.
4. Orange Peel
The occurrence of a bumpy surface similar to an orange’s skin, is referred to as “orange peel”. Several factors may be responsible for this painting issue, with improper adjustment of spray gun being the first. Other causes include:
- Forced drying method employing heat or fans, which is too quick
- Non-uniform mixture of material
- The wrong reducer type for the ambient temperature or the reducer not being enough (too thick)
- Spray painting when substrate or ambient temperature is too cold or too hot
- The flash time being too less between coats
In case of light orange peel, it can be buffed out or wet sanded using polishing compound. However, in extreme cases, you need to sand it smooth and then respray.
5. Sags and Runs
Sags and runs usually occur when too much paint is applied to a surface by moving the spray gun across the surface too slowly or holding the gun very close to the surface. Below are the other causes:
- Incorrect setting of the air-paint mixture in the spray gun
- Too much of reducer in paint (very thin)
To avoid sags and runs, follow the recommended thinning guidelines for the coatings applied as well as ensure that you follow the correct spray gun techniques, particularly on projected edges and vertical surfaces. If the sags and runs are dry, sand them out and repaint the surface.
Considering the significance of painting on airplanes, the paint job must be performed carefully by skilled aircraft painters to avoid the above mentioned or other types of aircraft painting problems.
Boca Aircraft Maintenance, one of the reputed aircraft painting companies located in Florida, has well-experienced aircraft painters providing excellent aviation painting services. If you are looking for reliable aircraft paint shops to give your airplane a fresh coat of paint, contact us or give us a call today!