The coating of any surface within the so-called industrial topcoats is the final working process that protects, beautifies and gives personality to a specific element or object. In many cases, the coating paint used in industry will be exposed to more severe environmental conditions or use than usual.
This situation therefore requires the application of particularly precise work processes to ensure the quality and durability of the work carried out. In this sense, it is crucial to know the most common painting defects that can occur in industrial coatings, both to eliminate them when they appear and, above all, to avoid them.
So, if you are interested in knowing relevant information about the most common painting defects that can appear in industrial coatings and spoil your work, don’t miss the following information we have chosen for you!
Origin of painting defects
There is a great variety of painting defects, and the reasons behind them are even greater and highly specific. However, generally speaking, the origin of these is almost always to be found in the different work processes applied by the professional as the work progresses. By knowing where it comes from, it is possible to raise awareness of the importance of any task, be it primer or topcoat, for tasks that are systematically carried out and their impact on the final finish. In this sense, painting defects have their origin in one of these three moments of the production process:
- Choice and purchase of paint. The chosen coating must always be the one that best suits the particular characteristics and context of the surface to be covered, taking into account such aspects as important as durability, the visual finish or the protection it offers. In addition, and no less important, is to ensure that products of sufficient quality are chosen, as this variable influences the performance of the products and the final topcoat obtained.
- Background preparation work. Before applying the topcoat, the surface preparation process required for each type of work and coating used is carried out. Some of the most significant tasks that have a direct influence on the appearance of defects are the decontamination of the surface, the removal of surface rust, priming the substrate or sanding the substrate with the appropriate grain size.
- Paint application and drying process. Each type of coating has a corresponding technical data sheet that precisely indicates all the aspects related to the explanation in terms of mixing ratios, evaporation time, drying time, etc. This information allows the professional to eliminate any improvisation that could lead to painting defects.
All these factors have a direct influence on each other, so the only way to guarantee the minimum risk of defects is to be particularly strict and careful in the application of the coating. In this way, and together with the experience and expertise of the professional, the risk of paint defects is significantly reduced.
On the other hand, the very nature of many of the works carried out in industrial environments is conducive to the appearance of problems after painting, since they are carried out in unfavorable conditions that are difficult to control, such as excessive humidity or the presence of rust on the steel, both of which are very common circumstances when working outdoors. The professional must take special care, when it comes to coating the surface, that they are aware of certain circumstances and work previously carried out, such as those related to construction, assembly, welding or any other type of repair.
Two common problems in industrial coatings
As we have already mentioned, after coating and drying of a surface, there is the possibility of certain painting defects appearing, especially when the processes of paint selection, primer preparation and application are not carried out thoroughly. In the case of the industrial sector, the two defects that we would like to highlight in this blog are oxidation and dullness.
Oxidation: Of the two defects, this is the most important, since any oxidation will eventually lead to corrosion if it is not properly corrected, weakening the metal and potentially compromising the structural function of certain components and assemblies. It is true that in industry, as a general rule, intermediate and thick metals are used, which slows down corrosion considerably. However, whenever steel sheets are used, this is a particularly important aspect to be taken into account. Be that as it may, the reality is that oxidation will always damage the topcoat used, so it should never be allowed to exist.
The oxidation phenomenon is generated in the primer work processes, when the steel is stripped and comes into contact with moisture. Since its formation is unavoidable in many cases, it should always be removed before applying any paint, either primer or topcoat. Below, we look at the causes, how to prevent it and the solution to the problem:
- Application of paint to rusty surfaces.
- Insufficient cleaning or sanding of the substrate.
- Prolonged exposure of the metal to environmental humidity.
- Paint system with an insufficient level of resistance to exposure to corrosive environments.
- For small defects, polish.
- For larger-scale damage, which requires high protection or a certain certificate, it is necessary to sandblast the surface to decontaminate it perfectly and repeat the entire coating process.
- Select a painting system according to the level of exposure to which the surface to be coated is exposed.
- Carefully apply the tasks involved in the preparation of the substrate, especially those related to sanding, cleaning and the use of primer paints.
- Prevent metal from being exposed to unprotected weathering.
Dullness: The other painting defect we would like to highlight is dullness. This problem occurs when the glossy topcoat paint loses shine after drying, leaving part or all of the painted surface with a dull appearance, lacking gloss and reflection. In this case, the origin of the defect is mainly due to the application conditions, although it may also be due to the incorrect execution of the primer preparation work. The causes of this imperfection are shown in detail below, as well as how to solve it and how to prevent it:
- Use of thinners that are too fast for the ambient temperature.
- Application of the paint in an excessively humid environment.
- Application times between coats too short.
- Sanding of primers too coarse.
- Handling paint without it being completely dry: masking, packaging, wrapping, etc.
- Polish the surface. If the dullness is more pronounced, sanding of the surface using micro-abrasives is essential.
- Use the reducers indicated by the manufacturer based on the ambient temperature in the application area.
- Whenever possible, the application should be carried out on air extraction and renewal equipment (booths or painting plenums).
- Observe the evaporation times between coats and always before forced drying.
- Ensure the drying time indicated by the manufacturer is adhered to before carrying out any other work on the painted surface.
Knowledge and experience = Better results
As we have seen, painting defects and problems are almost always caused by human error. For this reason, it is essential to make professionals in the industrial sector aware of the importance of each operation they are carrying out in the execution of a specific job. This reduces the risk of imperfections, such as dullness or oxidation, obtaining a better topcoat.