Aluminum: How to remove efflorescence?

Sometimes efflorescence can occur not only on walls and plaster, but also on aluminum. The cause of such efflorescence, and how best to remove it, can be found in this article.

Cause of efflorescence

Efflorescence on aluminum is not efflorescence, as is known, for example, from plaster or masonry. Efflorescence on aluminum is a special form of corrosion in aluminum.

Corrosion in aluminum

Usually aluminum is relatively corrosion resistant. This is due to a very thin and transparent oxide layer that normally surrounds the intact aluminum. This layer is usually very hard and stable. Even acids and alkalis in the pH range of 4.5 to 8.5 can not normally attack this layer.

However, if this layer, which is only very thin, is damaged, aluminum forms an oxide layer that is whitish and clearly visible. Over time, this layer then grows. It represents a kind of "self-protection" of the aluminum, which protects the metal against further corrosion.

Removal of the oxide layer

To remove this oxide layer, which prevents further corrosion as a protective skin, is difficult. In general, much sanding and polishing is necessary to get rid of the unwanted layer. It is very hard and also temperature resistant.

During grinding, it is important to rinse frequently with distilled water to remove the corrosive salts and chemical compounds from the aluminum. Failure to do so may cause the corrosion to restart and form a new layer of oxide. Mineral acids or strong alkalis may also help in removal.

Tips & Tricks

Painting or anodising aluminum is a very effective protection against this type of corrosion. The inherently protective layer, which is always invisible, is strengthened and stabilized in this way.

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