Anodising is an electrolytic surface treatment process that involves immersing your aluminium panels, sheets, shapes or extrusions in an electrically-charged sulfuric acid solution. This results in an aluminium oxide coating growing into and out of the surface of the aluminium, creating an attractive and durable metallic finish. Anodising is commonly used on a wide range of architectural products including façade panels, perforated panels, custom shapes and cladding extrusions.
Pre-treatment must be applied to the surface of an aluminium product to prepare it for the anodising process. Pre-treatment ensures the surface of the product is clean and free from particles which may cause corrosion or contamination or interfere with the anodising process. DECO offers a variety of different pre-treatment options, however chemical pre-treatment is our preferred method. DECO’s anodising pre-treatment line also offers an optional etching bath – chemical etching can be used to achieve a matte finish. Without etching, your anodising will produce a satin finish. Aluminium can also be brushed prior to anodising to create a stunning visual effect.
Before being anodised, the product is racked on specially coated aluminium or titanium racks, designed to conduct an electric current.
The product is then submerged in an acid solution with an electric current running through it, which releases hydrogen and oxygen, creating a build-up of aluminium oxide on the surface of the part. This oxide coating grows into and out of the product, converting the surface itself into a protective coating. This means the anodised coating is part of the product and will not peel or wear off. To achieve DECO’s AD and AD+ anodised finishes, parts are submerged in acids at ambient temperature. See below for more information on DECO’s ZD hard anodising processes.
DECO’s hard anodising technology is used to create DecoUltra’s highly durable hard anodised finish. DecoUltra ZD is a wear-resistant, corrosion and chemical-resistant 30 micron finish ideal for applications where the toughest, longest-lasting architectural finishes are required, such as on monumental projects or in areas with volatile climates including high moisture and pollution.
Just like DECO’s AD anodising process, the product is chemically pre-treated and racked on electrically conductive racks, before being immersed in a sulfuric acid solution. The electric current running through this acid bath is a much higher voltage than the current applied during the AD process. The temperature of the solution is lowered to around zero degrees, resulting in a thicker, tougher aluminium oxide coating growing on the product. This thick coating also has smaller pores, increasing its resistance to corrosion, abrasion and harsh chemicals. These pores are then typically sealed.
To find out more about DECO's ZD Hard Anodising processes and our industrial hard anodising options, including our 50+ micron DecoUltra ZD finish, click here.
Anodising can be coloured in two different ways: by dyeing the anodised product before the pores are sealed, or through an electrocolouring process. To find out more about these processes and DECO’s anodising colour range, click here.