From color to paint defect - through the eyes of a colorist

Painting errors and defects can occur at every stage of the painter's work and affect the entire scope of their work. A good knowledge of the craft allows them to be properly identified and eliminated. Ignorance and lack of proper work can result in the loss of a customer, so it is worth paying attention to a few problems that can occur when using certain colours.

Problems with paintwork and colour

 

The colour yellow

is rarely seen on streets and car parks and is not a favourite among painters. This is due to problems with coverage and colour matching. However, if you do paint it, remember to use a suitable primer. When choosing a shade for a car that is already a few years old, it is important to remember that the more you lighten the colour, the more noticeable it will be as green, and darker versions may turn into a shade of brown.

Orange and red

These colours are also not very popular with painters because of their poor covering power, which means that another layer of base coat, or primer, is necessary. It is essential to check the colour match with a test spray, as red does not forgive mistakes. It is usually the colour with the highest quantity in the mixer.

Clouding is particularly visible on these colours. To avoid it, apply the right amount of material and use the right pressure on the spray gun. It is also essential to remember to drop as the last finishing layer in effect colours. When tinting the colour, beware of the phenomenon of metamerism (the more ingredients added, the more the colour becomes ‘dirty’). If we are dealing with a vivid red colour and it is a bit too dark, it can be lightened with the base colour. Be careful with white, however, as too much of it can make you dizzy pink!

Blue

When colouring blue, try not to add a lot of ingredients (especially yellow and red), because when mixed in equal proportions they make black, which will make the colour dirty and dark. We must remember to choose the right clear coat – crystal clear, like CP 2016 VHS 2K 4:1 by Profix. It often allows you to bring out the seemingly invisible depth of blue colours. That is why it is so important to use a full line of products from one manufacturer.

White colour

We know very well that not all whites are the same, which is why it is important to check the OEM colour code. It is also important to consider the future, i.e. how the colour white may look when it gets older – it may turn yellow. Approximately 37% of all cars are white, and this colour has been at the top of the colour charts for many years. Therefore, it will often be a guest in our workshop. With this in mind, we should remember to use and choose the right clear coat, which also forms a protective layer against damaging UV radiation. It is also important to pour the quantities of the subsequent toners very accurately when preparing the formula, as three more drops can have a huge impact on the final result.

Green

It is an expensive pigment, so be careful when combining it with white, as you can literally deprive the colour of life. It is important to view the colour in different lighting conditions, preferably under D65 light (this is the colour temperature of white that most closely resembles daylight), because when viewed under D50 light, it can give the apparent impression that the colour is yellowish.

Black

You can laugh (some people probably cry), but you can see everything on black, especially dirt. By keeping the spray booth clean, we avoid the time-consuming polishing of the new coating. It is worth mentioning here that many customers want a black colour with exceptional depth and saturation. That is why we offer many solutions to help you choose the right colour, e.g. BlackPlus or JetBlack by Profix.

Metallic colour

Skill is needed here. The right pouring of the material is the basis to avoid problems with the grain arrangement. The colour can easily become too dark compared to the original if too much material is applied. The light will be our helper, but also an unrelenting controller, as defects become easily visible when reflected by it. Sometimes it is enough to change the proportions of the metallic pigments without adjusting the solid pigments. The issue with metallic grains is that fine grains appear light when viewed straight on and darker when viewed at an angle, while coarse grains are lighter when viewed at an angle and darker when viewed straight on. If we remove the grain that is most abundant from the recipe and it is a fine grain, the colour will darken when viewed head-on, but will remain unchanged when viewed from an angle.

 

Painting defects and car paint shop equipment

 

Car paint shop lighting

The right lighting is often the key to success in the paint shop. The colour on the production line should be checked under D65 light. Workshop lights must therefore reproduce these conditions as closely as possible to ensure a comfortable and effective repair. In addition to the place where the painting is done, light also plays an important role in the selection of colour. Colour is best judged in light that is as close as possible to daylight, i.e. natural light. It is therefore advisable to use lamps that emit exactly this kind of light with a white colour temperature (D65).

Paint spray gun

Washing spray guns properly helps to reduce clear coat defects. Disturbing inclusions flying out of the spray gun can occur when applying base or clear coat. This is nothing more than clear coat residue that has collected on the walls of the spray gun. Therefore, it is necessary to wash the spray gun after each painting job.

The air

Particular attention should be paid to compressed air filtration. The system should have filters that remove water and oil from the air. You can check the air purity with a well-known method that does not require any specialised equipment. Connect a male connector to the hose and blow air onto the mirror. If you do not see any impurities on it, the air is clean.

How to avoid painting errors?

What should you avoid to prevent complications such as pinholes, gas bubbles, craters and fish eyes? How do these defects differ from one another and how can you correctly assess the defect? Is it worth using a cutter at work?

Pinholes and other common defects

Precision and patience are essential when applying a clear coat. The most common defects include pinholes, blistering, craters and fish eyes. These defects are easy to recognise by their appearance, which is characterised by irregularities and bubbles in the clear coat.

The defect known as fish eyes usually occurs when the paint is applied too thickly. The incorrect application of the mixture disrupts the evaporation of the thinner. This results in the unattractive blisters and fish eyes that are the bane of many painters. The occurrence of the pinhole effect can be avoided. It is important to correctly assess the possible paint defect – a skilled workshop employee should know what layer thickness is optimal and will not lead to pinholes or outgassing, as well as unsightly craters and fish eyes.

Let's reduce the chance of making mistakes and remember to properly assess the layer thickness. Varnishing defects such as pinholes, blisters or craters are often the result of inexperience or haste. If you want to move on to the next steps as quickly as possible, you increase the chances of fish-eye errors occurring. Let's not forget about proper surface preparation, which can eliminate the need for touch-ups after blistering or craters appearing on the coating.

Evaluation and causes of errors

Why does blistering occur? Paintwork defects are not limited to the formation of pinholes. Workshop employees are confronted with many defects on a daily basis, such as blistering. This defect is easy to recognise by the appearance of the coating, which shows small bubbles. This defect is caused by the thinner in the applied mixture becoming trapped. It usually happens in a similar way to needle spraying, when the applied layer is the wrong thickness.

As you can see, the thickness of the coating can be the cause of many errors. The formation of bubbles is also favoured by too high a viscosity of the spray mixture. Blistering of the clear coat can also occur if the drying time is not observed. An incorrect assessment of the baking temperature also results in an error and the need for corrections.

How do I get rid of the blistering?

It goes without saying that it takes a long time to recognise and eliminate errors. However, if bubbles appear on the surface, the only option is to prepare the surface for a new treatment. In order to eliminate the blistering properly, the surface must be sanded. As with the needle-hole process, various tools can be used to level and abrade the surface.

Cratering and fish-eye effect

After a first assessment of their work, many painters also notice characteristic craters, also known as fish-eye effect, on the coating. These round or oval depressions of varying depths on the surface are usually caused by oil, grease, wax or silicone residues from previous work steps. Pinholes and fish eyes are caused by an unsanitary environment when applying the top coat. To avoid this error, the painter must also carefully inspect and evaluate his work clothes. Any remaining dirt on the clothes can also cause defects such as craters and fish eyes on the coating.

The procedure for removing craters and fish eyes is similar to that for removing pinholes and blisters. If we have not been able to prevent the coating from being applied incorrectly, we can still grind the defects. Craters and fish eyes can also be removed with professional grinding and levelling tools. This equipment will speed up the work and bring us closer to the point where we can apply another layer to the coating. Grinding and levelling tools are usually very easy to use and, in our opinion, give excellent results. They make removing the effects of crazing, blistering or craters, together with fish eyes, faster and more effective.

Which tools are useful for paint defects? A paint scraper is useful for removing paint defects, especially when the paint has been applied too thickly. Accessories like this will help you remove excess clear coat in specific areas. The scraper has a smooth surface to help you achieve the perfect result. This type of equipment does not require sharpening and retains its properties throughout its use. Using the scraper, we will remove defects that have already hardened.

To summarise, in order to achieve the most satisfactory result, we will have to focus on applying successive layers of clear coat - meticulousness and patience are what counts here. However, if we cannot avoid defects, all is not lost - by following the instructions, we can eliminate mistakes.