Types of metal finishes
Metal finishing is the final part of the manufacturing process and is used to improve aesthetics and the environmental protection of a product. These treatments can enhance the decorative appeal, increase durability and provide high chemical and tarnish resistance. It’s an extremely important part of the process and is applied to suit the project’s exact requirements.
All surface treatments are subject to rigorous in house quality standards and made to undergo a full inspection prior to manufacture and install. Also, metal finishes should be fully RoHS compliant to ensure any processes used are free from any hazardous substances and comply with the latest EU standards.
There are also another number of points to consider before choosing metal finishes from production speed, cost effectiveness and material density.
CASE STUDY PICTURED: Vintners Place, London. Rooftop planters featuring weathered steel.
Below are types of metal finishes available:
Hot Dip Galvanising.
Hot dip galavanisation is the process of coating iron and steel with zinc. The steel is dipped in a molten (830 F) bath of at least 98% zinc at an angle that allows the air to escape from tubular shapes or pockets, and allowing the zinc to flow into, over, and through the entire piece. Whilst immersed, the iron in the steel metallurgically reacts with the zinc to form a series of zinc-iron intermetallic layers and an outer layer of pure zinc.
Powder coating is applied to metalwork as a free-flowing dried powder. Often clients, designers and architects will specify powder coating for its durability to allow for maximised production, improved efficiencies and simplified environmental compliance. Powder coating is available in a limitless range of colours and textures, with technological advancements resulting in excellent performance properties.
Wet spraying is a traditional surface coating method by which a liquid coating is applied to a prepared surface in aerosolised form through pump devices at high pressure. In many applications, the paint is delivered via pneumatic-powered tools or machinery to achieve a consistent, even coat along a chosen surface. As powder coating benefits in reducing waste and increasing efficiency, wet spraying is easier to colour match to a client’s exacting requirements. The preparation techniques allow for surfaces to be completely joint and blemish free prior to the wet spray finishing.
Zinc Electroplating (BZP).
Zinc electroplating is commonly used and the most cost-effective process for coating metal to provide protection. The method includes the zinc coating slowly corroding away over time to protect the component underneath. A key benefit is the bright zinc plating itself improves the look of the base metal as clear zinc plating has a bright silver/blue appearance.
An electrochemical process that converts the metal surface into a decorative, durable, corrosion-resistant, anodic oxide finish. Aluminium is ideally suited to anodising, although other nonferrous metals, such as magnesium and titanium, also can be anodized. The anodic oxide structure originates from the base material’s substrate and is not applied to the surface like paint or plating, but is fully integrated with the underlying substrate, so it cannot chip or peel. It has a highly porous structure that allows for secondary processes such as powder coating or wet spraying.
Shot & Grit Blasting.
Shot blasting is typically used on metal parts for cleaning or removing old paint. Beads are projected through a specialist machine to remove impurities and restore the part to its original condition. Grit blasting is a type of protective treatment that attempts to smooth out a part, or in some cases provided a clean, hygienic, and aesthetically pleasing piece for sectors such as Food & Beverage and Pharmaceutical. Typically, particles are propelled against the surface of the part at a high speed to remove surface impurities to achieve the perfect finish.
Metal polishing is the process of removing scratches and abrasions from a surface and creating the desired brightness of finish on said surface. Polishing consists of several procedures, each of which are less abrasive than the previous; carried out using a combination of polishing wheels and compounds on a specialist buffing machine or hand tool.
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