Anodizing of Aluminium - Acidic Process Monitoring

Relevant for surface technology, treatment of aluminium products


Anodizing is widely used for protecting aluminum via an oxidic protection-layer against corrosion. At first the aluminum parts are cleaned and/or pickled using basic and acidic solutions to remove any residues from production (cp. “Can I monitor the composition of my pickling bath”). Then the anodizing process is performed in an electrolyte bath, commonly containing sulfuric acid. For this, the products are connected with the anode and hence an oxide layer is built on the surfaces of the parts. In many cases colorization of the products is carried out afterwards. Sealing of the new surface with hot water finalizes the process.

Process electrolyte bath monitoring

The bath where the anodizing is carried out contains mainly sulfuric acid, aluminum-sulfate and water. To ensure a constant composition of the bath, customer specific acid and salt concentration is continuously monitored and thereby a constant high quality of the protective film is guaranteed.

Anton Paar provides L-Com were density and sound velocity measurement is combined in one instrument. For this application a L-Com made of Hastelloy combines high precision with reasonable price and short payback time. According to customer wishes the bath composition can be varied and thereby a constant high quality of the protective layer and stable process conditions are guaranteed.

Process density and sound velocity sensor L-Com 5500

The density and sound-velocity sensor L-Com 5500  from Anton Paar continuously displays the concentration of the acid and salt concentration in the bath. Furthermore maintenance free construction allows operating times for many years. These benefits are combined with high accuracy, robust design and cost efficiency. Due to the optimized process conditions and to the fact that no consumables are required for measurement, the payback time for the sensor is quite short.


  • Optimizing throughput
  • Constant quality monitoring
  • Reducing acid consumption
  • Stable results
  • Highly accurate

Learn more about L-Com 5500


Specifications L-Com 5500:

Measuring range: 2000 kg/m³

Process temp. range: -5 °C to 80 °C

Ambient temp. range: -25 °C to 60 °C

Process pressure: max. 50 bar (abs.)

Typical repeatability: 0.01 kg/m³

Other relevant instruments

Process Instruments:

  • Pico 3000 (RC)



Do you have any questions?

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