Sheet metal finishes. They can look nice, but more importantly, they can resist corrosion. Their lifespan can be longer. And they can be suited for a particular environment.
Powder Coating
Powder coating is one of the most cost effective finishes for sheet metal components. Most powders are electrostatically applied and then dry in the air before being cured in an oven to create a tough and even surface. There are a wide range of colours available for both steel and aluminium parts and it also provides a good level of impact resistance. It is suitable for parts that are used mainly indoors or in mild outdoor conditions.
Anodising
Anodising is an electrochemical process that can be applied to aluminium surfaces to create a thick, durable layer to protect against corrosion. Anodised surfaces can be left as clear or coloured anodised coatings. The anodised layer is integral to the aluminium surface, it will not peel.
Hot-Dip Galvanising
Steel parts are dipped into molten zinc to provide complete protection to all edges and internal surfaces of the part. It is ideal for use in outdoor or industrial environments where rust can be a real problem. The process of hot-dip galvanising and the resulting protection to steel is described in greater detail on the UK Galvanizers Association website, including the relevant performance standards.
Brushed or Mill Finish
A brushed or mill finish is simply sheet metal, left largely as it comes. This means that there is no added coating, thus the product is of low cost and has short lead times. The finish has a consistent directional grain which has been produced by abrasive brushing.
Electroplating
Thin layer of metal (normally nickel or chrome) electroplated onto the surface of the part to give better corrosion resistance and smooth reflective surface.
If you are looking for Sheet Metal Fabrication, see dkmsheetmetal.co.uk.
By matching the finish to the metal, the environment and budget of your project you will save time and rework later.