Powder coatings are a free-flowing, dry powder medium applied to a coating to protect or enhance the properties of parts, components, surfaces, or other substrates. These coatings do not require a solvent to keep the binder and filler components in a liquid suspension, differentiating them from conventional liquid paints and coatings. Powder coatings are typically comprised of various thermoplastic or thermoset polymer materials.
Masking dots, on the other hand, are circular- or disc-shaped polyester films, single-coated with a silicone-based pressure sensitive adhesive (PSA). The discs are die-cut on a formulated fluorosilicone liner to ensure a stable release. Masking dots for powder coatings are used to cover – or mask – specific areas of the substrate during powder coating operations.
Powder coatings work by combining polymer resins, curatives, pigments, leveling agents, and other components in a containment unit. The elements are melted, mixed, cooled, and ground into a uniform powder form. The powder is then pumped through a hose to the nozzle of the spray gun where an electric current applies an electrical charge to the powder coating particles.
The charged particles released from the nozzle are attracted to and subsequently stick to the grounded component being coated. Once the part is coated as desired, it is placed in a curing oven, where the application of heat results in chemical reactions which harden the powder coating.
When powder coatings are being applied, there may be certain areas of the substrate that must remain free of paint and foreign matter. Coatings that are applied to threaded parts or precise bearing surfaces, for example, can result in issues regarding tolerances and performance.
In electronic or electrical devices, some areas may also need to be bare for grounding and electrical contact applications. In these situations, masking dots act as barriers which block the powder coating from coming into contact with these surfaces. The circular shape of the dots makes them ideal for precisely covering holes and other irregularly-shaped areas.
One of the other significant benefits of painting masking dots lies in the formulation of its adhesive. While the pressure sensitive adhesive is capable of maintaining its bonding strength during powder coating operations, it is also designed to be easily removed from the surface without damaging the substrate or leaving unsightly residue.
Additionally, polymer-based films are more durable and reliable than paper masking tapes. Polyester masking dots, in particular, can be used in applications containing harsh chemicals such as etching and plating. Furthermore, these films can be used in electrical applications due to their resistance to molten solder.
Masking is one of the most time-consuming tasks in the powder coating process. However, without the right masking, there is a risk of causing damage or failure of the component at hand when the coating or paint is applied.
Robert McKeown Company can help with this frustrating problem. We offer powder coating and painting masking dots to protect the vulnerable portions of any part. These dots can be applied very accurately to cover only the necessary sections of the component while leaving the rest available for coating.