05/10/2023

How to avoid bubbles and porosity on powder coating applied to a cast metal surface

Powder coating is a technique that provides an extremely durable coating. However, defects such as bubbles, pinholes, craters, or porosity can occur and, in addition to spoiling the coating’s aesthetic appearance, they can compromise its functionality, quality and durability over time. There are several reasons for these defects, but they can be avoided with a few tricks.

Substrate preparation

It is essential that the substrate is clean, dry and free of any contaminants before applying powder coating. This is especially true for exhaling substrates, such as steel castings, galvanized steel, aluminum and its alloys, as these metals can release entrapped gasses during curing. To achieve a clean and smooth surface that facilitates the coating film’s adhesion, removing all traces of oil, grease, rust, or other residues from the substrate is necessary.

Environmental conditions

Environmental conditions also affect the result of powder coating. If the environment where the application is done is too hot or too moist, this can create adverse conditions for the application.

The best conditions for application are a maximum temperature of 35°C and Humidity between 20-70 %.

Powder coating selection

Once the substrate has been prepared, the selection of a suitable powder coating becomes critical.

To achieve the best results on this type of substrate, it is important to use a quality powder coating that promotes outgassing and allows the entrapped gasses in the substrate to escape.

RIPOL’s OGF Series consists of powder coatings based on polyester resins (topcoat, single coat) and epoxy or epoxy-polyester (primer), formulated with enhanced outgassing characteristics for applications on exhalant substrates. These coatings are designed to mitigate the expulsion of gas during the powder coating curing process, preventing the generation of bubbles and promoting an optimal aesthetic result.

The OGF polyester series also offers excellent weathering, UV and good chemical resistance.

Coating Application

Finally, to achieve good coating distribution and adhesion, air pressure, electrostatic tension, distance and spray angle must be carefully adjusted, remembering to apply the coating in thin, even layers.

By carefully following all these steps, the powder coating will result in a smooth, homogeneous, defect-free and durable finish capable of meeting aesthetic and functional customer needs.

We encourage you to contact us for any questions or concerns about powder coating.

PRESS

Liquid or powder coating: which one to prefer and why?


Have you ever wondered what advantages a powder coating brings over a liquid one? Read on to clarify any doubts. Right from the first phase, it is necessary to be clear about the end use of the item and consequently choose the correct materials and coatings to avoid nasty surprises. Coating a surface means improving it aesthetically and protecting it from wear, chemical agents, and weathering.

Read more

Corrosion, how to prevent it


Steel is a material easy to work with, very strong and light, but subject to deterioration if not protected. RIPOL powder coating products have obtained QUALISTEELCOAT certification for the RIPOL Corrocare ABP primer used in combination with RIPOL 59L, 58L, 52L, 55R series finishes.

Read more

Camouflage powder coating for military vehicles


RIPOL enriches its product portfolio with RIPOL RAL 6031-F9 Matt Bronze Green - code 61LV1G76312. The new coating is specifically formulated to meet the requirements of military standards to reduce the detection of surveillance and seeker systems in the visible and near-infrared spectral range, as it provides reflectance to the vehicle and perfect camouflage.

Read more

Change the look of your surfaces with RIPOL Clear-Sandy


RIPOL Clear-Sandy, the new matt fine-textured clearcoat, is a unique coat that can change the look of a smooth powder-coated surface into a fine-textured surface, further improving its durability.

Read more