Fumes extraction is desirable on all etching and anodizing tanks as the hydrogen evolves during the processes and carries fine drops of caustic soda and sulphuric acid. The ducting is normally made of PVC or polypropylene, but stainless steel has also been used in some plants. Push-pull extraction systems are sometimes used. In most areas the fumes will require scrubbing in dilute acid/alkali or in water before being released into the atmosphere.

Special wetting agents are sometimes used to give thin foam blanket on the surface of the solutions, in order to reduce the amount of fume extraction, but because of the vigorous agitation, care is necessary to avoid additives which foam too much.

In addition the presence of additives on the surface of the aluminium sections or parts must not affect subsequent processes such as colouring or sealing.