5 Common Aircraft Painting Problems and their Solutions

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. 

2. Blushing 

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.  

3. Pinholes 

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.   

 

Wrap Up 

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! 

5 Types of Primers Used in Aircraft Painting and Finishing

The value of primers iaircraft painting and finishing is usually underestimated and misunderstood as it is invisible after application of the topcoat finish. Nevertheless, a primer serves as the foundation of finish. The role of primer is bonding to the surface, inhibiting metal corrosion, and providing an anchor point for coats of the finish.  

The primer pigments should either be anodic to surface of the metal or passivate the metal surface if moisture is present. The binder and the finish coats should be compatible with each other. Primers for surfaces that are nonmetallic, don’t require passivating or sacrificial pigments.  

Following are some of the chief primer types used for aircraft painting and finishing. 

Primers for Aircraft Painting and Finishing 

1. Wash Primers

Wash primers are coating of phosphoric acid in a solution of alcohol, vinyl butyral resin, and other ingredients. These primers give water-thin coatings, have very low amounts of solids, and have no filling qualities. The functions of these primers are passivating the surface, providing corrosion resistance temporarily, and offering an adhesive base for next coatings, like an epoxy or urethane primer.  

Wash primers have remarkable corrosion protection qualities and don’t need sanding. The recoat timeframe for some of them is very short that should be taken into account while painting larger airplanes. Follow the manufacturers’ instructions to get satisfactory results.  

2. Gray Enamel Undercoat

This is a nonsanding, single component primer compatible with various topcoats. Gray enamel undercoat has a high corrosion resistance, dries quickly without any shrinkage, and fills minor imperfections.  

3. Red Iron Oxide

An alkyd resin-based primer coating, red oxide primer was developed to be used over steel and iron in mild environmental conditions. You can apply it over rust which is free of grease, oil, and loose particles. This primer type’s use is limited in aviation industry.  

4. Epoxy

A thermosetting, synthetic resin, epoxy produces hard, tough, chemical-resistant adhesives and coatings. Epoxy uses a catalyst for activating the product chemically, but it’s not identified as hazardous as it doesn’t contain any isocyanates. This primer type can be employed as a nonsanding sealer/primer over bare metal. It’s softer compared to urethane and has a good chip resistance. Epoxy is recommended to be used over steel tube frame airplanes before installing fabric covering. 

5. Zinc Chromate

A corrosion resistant pigment, zinc chromate can be added in primers made of various types of resins, like alkyd, polyurethane, and epoxy. Zinc chromate of older type can be distinguished by its bright yellow hue as compared to the current brand primers that usually have a light green color. Zinc chromate reacts with metal surfaces because of moisture present in the air, forming a passive layer which prevents corrosion. At one time, zinc chromate was the standard primer for painting of airplanes. However, it has now been replaced due to environmental concerns and the emergence of new formula primers.  

 

These are the key types of primers used in aircraft painting and finishing. If you are looking for airplane painting services, Boca Aircraft Maintenance can provide you quality aircraft painting and finishing services. Being one of the leading aircraft painting companies in Florida, we specialize in aircraft exterior painting.

6 Types of Finishing Materials Used for Aircraft Painting and Finishing

The purpose of aircraft painting and finishing is not just enhancing the aesthetics of an airplane. Aerospace paint protects an aircraft frame’s integrity and influences an airplane’s weight. Finishing is applied for safeguarding the exposed surfaces of an aircraft from deterioration and corrosion. There is a broad range of finishes and materials available that are employed to protect the outer surface of the aircraft and offer the desired look to the plane.  

Decorative finishing of airplanes includes application of letters, identification numbers, decals, addition of emblems and company logos, and trim striping.  

Finishing Materials Used for Aircraft Painting and Finishing 

Among the broad range of materials used in airplane finishing, some of the common materials are discussed as follows: 

1. Acetone 

A fast-evaporating solvent with no color, acetone is an ingredient in varnish, nail polish, and nail removers. For most plastics, acetone is a strong solvent and is effective for thinning adhesives, vinyl, polyester resins, and fiberglass resin. It serves as superglue remover too. This solvent is a heavy-duty degreaser that’s fit for metal preparation as well as grease removal from fabric covering before doping. Its use as thinner in dope should be avoided due to its fast evaporation that causes the doped region to cool and gather moisture. The absorbed moisture hinders uniform drying and leads to the dope’s blushing and a no-gloss, flat finish. 

2. Alcohol 

Butyl alcohol or butanol is a solvent that dries slowly and can be combined with aircraft dope for retarding the dope film’s drying on humid days, thereby preventing blushing. A dope solvent mixture having 5-10% butanol usually serves this purpose well. Ethanol alcohol and butanol are mixed in ratios that range from 1:1 to 1:3 for diluting wash coat primer in spray applications since butanol retards the rate of evaporation.  

Denatured alcohol or ethanol is employed as a component of varnish and paint remover. Ethanol also serves as a degreaser and cleaner prior to painting.  

3. Methylene Chloride 

A volatile, colorless liquid, methylene chloride is completely miscible with various other solvents. Methylene chloride has wide application in paint strippers, and it’s also used as a degreaser/cleaning agent for metal parts. Under normal conditions, it doesn’t have a flash point and can be employed for reducing other substances’ flammability.  

4. Turpentine 

The wood of certain pine trees is distilled to obtain turpentine. A water-insoluble and flammable liquid solvent, turpentine acts as a thinner as well as a quick-drier for enamels, varnishes, and other types of oil-based paints. It’s also used for cleaning paint brushes and paint equipment used with any oil-based paint.  

5. Mineral Spirits

Also known as petroleum spirits, Stoddard solvent, or white spirit, mineral spirits is petroleum distillate employed as a mild solvent and paint thinner. This is the most broadly employed solvent in paint industry, utilized in varnishes, lacquers, wood preservatives, paints, and aerosols. Mineral spirits are also used commonly for cleaning paint equipment and paint brushes. It finds use in degreasing and cleaning machine parts and tools due to its effectiveness in removing greases and oils from metal. Mineral spirits are less toxic, less flammable, and has low odor than turpentine.  

6. Varnish

A protective, transparent finish, varnish is used primarily for finishing wood. Varnish comes in exterior and interior grades. Compared to the interior grade varnish, the exterior grade varnish dries less hard, and contracts and expands with variations in temperature of the material that needs to be finished.  

Traditionally, varnish is a mixture of a solvent or thinner, a resin, and drying oil. It has no added pigment, is transparent, and has little to no color. The drying of varnish is slower than most of the other finishes.  

 

Every aircraft finishing material comes with its own characteristics. When choosing a finishing material to be used in aircraft exterior painting, determine your needs first and choose accordingly. If you are looking for quality aircraft painting services or weatherproof aircraft painting in Florida, Boca Aircraft Maintenance can provide you the finest quality aircraft painting and finishing services.  

Types of Aerospace Paint for Aircraft Painting and Finishing

Aircraft painting extends beyond aesthetics; paint protects the airframe’s integrity and affects the aircraft’s weight. The topcoat finish protects the aircraft’s exposed surfaces from deterioration and corrosion. Additionally, an aircraft that’s properly painted is easier to maintain and clean as the exposed surfaces have higher resistance to dirt and corrosion, and oil doesn’t stick to the surface as readily. 

A broad range of materials is used for aircraft painting and finishing that provide the airplane with the desired appearance and protect its exterior. The term “paint”, used in general sense, includes lacquers, enamels, primers, and different multipart finishing formulas. There are three components in paint – resin as the coating material, solvents for reducing the mix to reach a workable viscosity, and pigment for color.  

Unexposed components and internal structure of an airplane are finished to safeguard them from deterioration and corrosion. All exposed components and surfaces are finished for an aesthetic appearance and protection.  

Classification of Aircraft Paints 

This post is focused on the classification of aircraft paints. Following are the chief types of paints used for aircraft painting: 

1. Dope 

When fabric-covered airplanes were predominant, the standard finish used for protecting and coloring the fabric was dope. Dope provided several qualities to fabric covers, such as increased tautness, UV protection, weather-proofing, airtightness, and tensile strength. Essentially, aircraft dope is a colloidal solution consisting of cellulose nitrate or acetate mixed with plasticizers to form a homogenous, flexible, and smooth film.  

Dope is still employed on fabric-covered airplanes as part of the covering process. Nevertheless, the fabric type being used for covering the airplanes has changed. Linen or grade A cotton was used for years as the standard covering. It may be used still if it fulfills the FAA (Federal Aviation Administration) and TSO (Technical Standard Order) C-15d/AMS 3806c requirements. The aviation industry is now dominated by polyester fabric coverings. Especially developed for aircraft, these new fabrics are far better than linen and cotton.  

2. Synthetic Enamel 

Synthetic enamel – a single-stage, oil-based paint for aircraft exterior painting – offers protection and durability. The shine and durability can be increased by mixing it with a hardener while lowering the drying time. Synthetic enamel is an economical type of aircraft finish.  

3. Lacquers 

Lacquer’s origin dates back to hundreds of years. Lacquer originated from a resin which is obtained from certain trees that are indigenous to China. Nitrocellulose lacquer was made in early 1920s through a process using wood pulp and cotton.  

Nitrocellulose lacquers result in a semi-flexible, hard finish which can be polished for obtaining a high sheen. With aging, the clear variety may yellow, and it can also shrink over time leading to surface crazing. In the automotive industry, lacquer was the first type of coating used in mass production, since it diminished the finishing times to two days from about two weeks.  

To resolve the yellowing problems, acrylic lacquers were made. The working properties of acrylics are almost the same, but on drying, the film is more flexible and less brittle than in case of nitrocellulose lacquer.  

Lacquer is an easy paint to spray as it’s quick to dry and its application can be performed in thin coats. Lacquer, however, is not a highly durable paint for airplane painting. Gasoline spills, acid rain, and bird droppings can eat down into it.  

Lacquer’s current use for aircraft exterior coating is almost nonexistent due to environmental and durability concerns. About 85 percent or more of the VOCs (Volatile Organic Compounds) in spray gun are released to the atmosphere when lacquer is used, and its use has been banned by some states.  

Some lacquers have been developed recently that employ a catalyst, but these lacquers are mostly used in the furniture and woodworking industry. These are nitrocellulose lacquers with ease of application due to much better abrasion, chemical, and water resistance. Moreover, lacquers with catalyst cure chemically, not through evaporation of solvents only. So, the VOCs emitted into the atmosphere are reduced.

4. Polyurethane 

Polyurethane is the best option when compared to aerospace paint of other types, for its properties of chemical, stain, and abrasion resistance. The wet look was introduced by polyurethane. It exhibits a high natural resistance to UV rays’ damaging effects. Usually, polyurethane is the preferred option for corporate aircraft painting and finishing in the aviation environment of today.  

 5. Urethane Coating 

The term urethane refers to certain binder types used for clear coatings and paints. Urethane is typically a coating in two parts consisting of a catalyst and base, which when mixed, generate a high-gloss, durable finish with chemical and abrasion resistance.  

 6. Acrylic Urethanes 

Acrylic means plastic. It provides a harder surface on drying but its resistance to harsh chemicals is less than that of polyurethane. Most of the acrylic urethanes require the addition of extra UV inhibitors when subjected to the sun’s UV rays.  

These are the key types of aircraft paints. If you need your airplane painted, consider choosing one of the most reliable aircraft paint shops so that your airplane gets the finest quality painting.  

Why Your Aircraft Needs a New Coat of Paint and Regular Aviation Bodywork

Your aircraft is a precision machine. It is much more complicated than an automobile, boat, or a locomotive. Airplanes also face a lot more weather damage than most other types of vehicles. Hence, regular aviation bodywork and aircraft paint jobs are extremely important. However, an end-to-end airplane evaluation should also be a part of the agenda.

Without a reliable aviation company for annual body check-up and repairs, your machine will start developing faults. These may be minor faults to begin with, but they soon pile up. Eventually, your airplane will start showing major issues. The best aircraft maintenance companies like BAM suggest that your aircraft should get at least two check-ups a year.

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