Efflorescences

What is efflorescence?

Efflorescence is created when water soluble salts deposit on the clinker brick facade. It typically manifests as a white, dust-like coating on the brick’s surface.

 

picture: Fachverband Ziegelindustrie Nord

What causes efflorescence?

Efflorescence may occur if salty mortar was used and if moisture penetrated the masonry through excessive water absorption. Capillary action within the brick transports the salts to the clinker brick’s surface where they crystallise. According to DIN 105 („Mauerziegel“ [1]) bricks should only contain  0.08% salts, while jointing mortar has a much higher salt content. The DIN 1053 („Mauerwerk“ [2]) states which jointing mortar is best to use.

Prevention

Efflorescence only occurs due to inproper processing of clinker bricks. During the grouting phase, masonry, and especially the joints, are very sensitive. Meaning one should prevent any moisture penetration of the masonry right at the beginning. This is why it is so important to cover up the freshly build brick work, and why there shouldn’t be any work done during heavy rain. Choosing a jointing mortar with a low salt content is significant as well.  (DIN 1053 „Mauerwerk“ [2]; Check out tips about ‘joints and grouting’ by Gillrath)

How to proceed against efflorescence.

Usually efflorescences only effect the optical appearance and have no influence on the building materials. The leaking salts at the clinker facade should get brushed away regularly with a scrubbing brush. The atmospheric influences will get rid of the remaining soilings.

Be careful about using hydrochlorid acid

Usually the utilisation of hydrochlorid acid does more harm than good. If the acid is used inproperly, efflorescences and discolorations could occur.