The Anodising Process

ABL has over 35 years of anodising experience and is one of a very few companies in the UK that combine fabrication and anodising on the same site.

Anodised Finishes include;
— Natural (silver) AA3 to AA25
— Black or Gold
— Alocrom 1200

The Anodising Process consists of:


The profile is dipped in an alkaline detergent and heated to around 120-140°f. This removes any grease and other contaminants before etching.


Etching is a chemical process done using Caustic Soda ( Sodium Hydroxide ). This method is used to remove minor imperfections on the surface of the aluminium for instance dust, oil and oxide. Etching is usually done before anodising and depending on the length of time the profiles are in the etching tank, different surface finishes can be achieved.


Rinsing takes place after each stage of the anodising process and is done using De-Ionized water.


This process removes unwanted surface alloy particles by dipping into an acidic solution.


The aluminium is immersed in a tank containing an electrolyte having a 15% sulphuric acid concentration. The aluminium becomes the anode and the tank becomes the cathode as an electrical current is passed through the electrolyte. Once the voltage is applied across the anode and cathode it causes the negatively charged anions to migrate to the anode. The oxygen in the anode combines with the aluminium to form aluminium oxide, which is the anodic film. The depth of the anodic film is determined by the length of time the aluminium spends in the anodising tank. The quality of the anodic film is determined by the temperature and concentration of the current and the electrolyte that is applied. The anodic film is very porous and must be sealed to achieve the desired weather resistant properties.


Anodic films are well suited to a variety of colouring methods. If any colour is required other than natural, the colour is applied now before sealing. A vast array of colours is available.

ABL offer Natural / Silver, Black and Gold finishes.


In all anodising, proper sealing is very important and absolutely essential to the performance of the coating. The pores must be non-absorbent to provide maximum corrosive protection. Sealing is done by immersing the metal into boiling hot di-ionized water although not completely effective and does reduce the resistance by about 20%.

Cold Sealing where the pores are closed, by the impregnation of a sealant in a room temperature bath and is more popular due to energy savings.

Free Anodising Download

Not sure how anodising can benefit your product or want to understand more about anodising? Click here for a free PDF download of anodising explained or view as a web page here.

ABL can offer the appropriate supporting QA documentation for anodizing and polishing processes which allows us to supply the automotive industry, where process capability is key.

Centurion uPVC installers

ABL Aluminium Components specialises in the fabrication, finishing and assembly of aluminium extrusions. The company was set up over 30 years ago and operates from a 5000m2 facility in Birmingham, just 5 miles from Birmingham airport and the motorway network.

ABL Aluminium Components is privately owned with a turnover of over £4m and a skilled workforce of 60 employees. The business adopts a very high customer service ethic which it brings to the various market sectors it serves.