Colours and treatments
When it comes to surface treatment of aluminium profiles, there are three options; mill, anodising, and powder coating. These options are available for extruded louvers, rack arms, supports, motor tubes, motor hoods, and drive shafts.
Mill, or mill finish, means in fact untreated. It is the state in which aluminium comes from the extruder – the mill. All mill aluminium has light oxide film, which appears naturally. A mill finish is always without intended fysical or chemical finishing. Mill aluminium is suitable for anodising and coating.
Anodising is the electrolytic process of increasing the thickness of the natural oxide layer as mentioned above. Anodising is a controlled process where an oxide layer is added to the surface of the aluminium to improve its resistance to wear and corrosion. This oxide layer has typically a thickness of 5 to 30 µm.
The most poluar type of anodising is natural anodising. When protecting against wear and corrosion is the main motivation for treating the surface, then natural anodising an obvious choice. It is an economical option, and popular for projects not visually accessible and industrial applications where appearance is less relevant.
Anodising in colour is also an option. Available colours are silver, gold, bronze, copper, grey, black, blue, red, green. The anodising layer is transparent, meaning the colour, gloss and structure of the end product depend on the material and its pre-treatment. Popular pre-treatments are grinding, brushing, and polishing.
Powder coating is possible in all standard RAL colours. RAL powder coating results in a colourful and smooth surface. Adding structure colours and structures are possible on request. A overview with most common colours is given below.
Standard RAL colours are defined by a specific RAL code. Sunshield distinguishes standard RAL colours and non-standard RAL colours. A standard RAL colour is a colour without structure or metallic particles, and known as a four digit number in the RAL system. Like for example RAL 9005 – Jet Black.
Standaard RAL colours deliver a smooth surface. Mixing a standard RAL colour with a powder results in a sruface with a structure, which gives a more exclusive impression. Another example of a custom made colour is a RAL colour mixed with metallic particles to give the painted surface a metallic shine. Custom made colours and structures are possible at request.
Generally, louvers and components are coloured by powder coating. A dry powder is applied electrostatically to the surface, and cured in an industrial oven. Powder coating results in a harder, and more durable finish than conventional liquid paints.
Another parameter with regard to colours is gloss, expressed as a percentage. Common gloss degrees are 70% and 30%. Sometimes also referred to as high gloss (70%) and matt (30%). A colour with 30% gloss is less brilliant than a colour with 70% gloss. The advantage of the 30% gloss is that scratches are less visible, than with 70% gloss. That is why some customers, especially for external solutions, prefer 30% over 70% gloss.