Alkaline pickling

Alkaline cleaners are divided into etching and not or barely etching cleaners. A higher lye concentration and a higher temperature accelerate the pickling process, but as a result the pickled surface is also rougher. Strongly etching cleaners, usually based on sodium hydroxide, are used if there is a thick oxide skin or if degreasing must take place. This is a very fast pickling process with a mat exterior quickly originating. Not or barely etching cleaners based on silicates and carbonates are used if there are only small amounts of grease or oil on the aluminium surface.

General pickling conditions:
– Temperature: 50 – 70°C
– Time: 5 – 15 minutes