Orange Peels in Wood Furniture Finishing

Orange peel is a rough and uneven or textured surface, like orange peel at the film layer or finish surface. Orange peel is considered one of the finishing problems because it ruins the beauty of the finishing layer. At the simple finishes, especially those with low gloss, some thin orange peel may not be visible and interfere with the finishing appearance. But orange peels on dark colors (black or dark brown) with a gloss look will appear very clearly and interfere with the finishing look. In high-end products that require perfect appearance quality, the presence of orange peel will reduce the quality of the finishing and ultimately reduce the quality of the product. Very heavy orange peel will even affect the strength of the finishing layer.

Causes of Orange Peel

Orange peel is generally caused by imperfect material flow when the paint layer is applied. Ideally, every time a layer of paint is applied, it can flow evenly over the entire surface of the object before it dries and hardens. If the paint layer does not flow properly and the paint layer dries too quickly, the resulting film surface becomes rough and uneven, like orange peel.

In practice, there are several things that cause orange peel, such as imperfect application techniques, coating that is too thick, material that dries too quickly, poor sanding, and environmental factors such as temperatures or humidity.

• Imperfect application techniques

The coating processes that are not perfect, such as too thick coating, improper sanding, and imperfect atomization, are the main factors that most often cause orange peel problems in the field.

• Improper material setting and quality

Material that is too thick or dries too quickly will make the material flow imperfectly, and this will result in orange peel problems on the applied paint layer.

• Environmental factors

Environmental conditions are also the cause of orange peel problems. Humidity that is too low and air temperature that is too high will make the drying process of the finishing layer fast and affect the flow of the paint layer and can cause orange peel problems.

How to solve the orange peel problem

This orange peel can be removed with a good sanding process. Good sanding can be done to cut the texture of the orange peel on the surface so that it produces a flat and smooth surface. Then, with another coating layer on top with the right technique, the orange peel will disappear and a flat and smooth surface will be obtained.

This orange peel will only be a problem if it is found at the last topcoat application since it will stay until the film dries. The presence of orange peel on the sealer, primer, or base coat will not be a problem because they can be cleaned by a good sanding process. With good and perfect sanding, all uneven surfaces can be cleaned and then followed with a good topcoat application; orange peel will not appear on the surface.

Things to do to prevent and overcome the problem of orange peel.

• Correct spray gun usage technique

Application by spraying is the best way to produce an even and smooth coat of paint. However, to produce a perfect coating, the right application technique is needed. There are 2 things to be considered in the spray application: spray gun settings and spray gun movement techniques. The spray gun is set with the main goal to make the finishing material able to be perfectly atomized before being directed to the desired surface. These tool settings include setting the material volume, spray direction, and air on the spray gun. More about spray gun settings can be viewed at our previous post: spray gun settings.

The spray tool movement is set to ensure that the paint coats the surface evenly with the desired thickness. Material that is too thin or too thick will result in a rough, uneven surface and orange peel. The tool movement settings include several things: the distance between the spray gun and the surface and the speed and consistency of the spray gun movement. A more detailed explanation of the technique of using this spray gun can be seen in our other article: how to move spray gun

•  Tool settings

If the paint is applied with other tools such as a roller coater, curtain coater, or other tools, then good tool settings are needed to be able to produce a perfect paint coating. Check and see the specifications of the tool; make sure the paint applied is in accordance with the specifications of the machine used. Adjust the tool according to the desired results (paint thickness, production speed and volume, material thickness, etc.), and adjust the material according to the needs of the machine, such as viscosity, concentration, drying speed, etc. 

• Good sanding

Good sanding is one of the important keys to overcoming and preventing orange peel. Orange peel that is found at the finish film can be cleaned and removed with a perfect sanding process. Meanwhile, the presence of imperfect film will continue to appear when it is layered with another coating on it. Therefore, do good sanding every time you apply paint. Make sure the surface is flat and smooth, with no orange peel, before continuing with the next paint coating process.

• Avoid applying paint that is too thick

Too thick coating application tends to make the material flow less which will ultimately invite problems. Therefore, apply paint with a reasonable thickness. Check the material specifications for the recommended thickness for each application layer. If a thick film layer is needed, then apply the paint in many steps. Make sure each layer is applied with a reasonable thickness, dry and sanded well before being coated with the next layer.

• Control the viscosity of the material

Every spray gun type and finishing equipment has a viscosity limit where they can work perfectly. Check and control the viscosity of the paint to be applied; make sure it is in accordance with the specifications of the tool and equipment used for its application. Avoid using paint with too high viscosity, because it will be difficult to atomize and flow perfectly.

• Use good-quality finishing materials

The quality of finishing materials is one of the main factors that determines the quality of the finishing results. To prevent orange peel, make sure the paint you use can flow well, according to the tools used. Use the right solvent according to the type of material and the desired settings. If necessary, some additives can be added as needed.

• Be aware with environmental conditions

Extreme environmental conditions can also cause orange peel problems. Paint is generally designed to be used in normal environmental conditions; however, there are some paints that are sensitive to environmental conditions. PU and water-based are sensitive to environmental conditions, especially humidity and air temperature. When the temperature and humidity change from ideal conditions, it can affect the drying process of the material. Therefore, measure and check the humidity and air temperature in the finishing room so that you can anticipate if there are problems related to environmental conditions. 

• Rubbing and polishing 

This orange peel problem can actually be solved with good sanding. Good sanding will cut the texture and orange peel so that it produces a flat and smooth surface. If you are going to do the rubbing and buffing process, then the orange peel can be solved with good sanding at the beginning of the buffing process. When the entire surface texture is completely cut off and a flat and smooth surface has been obtained, the buffing and polishing process can be carried out with perfect results.