Efflorescence
Efflorescence, often referred to as "lime bloom", is a natural phenomenon and is found in products containing cement.
It is a white deposit which appears on the surface of all concrete based products, and can be unsightly whilst it lasts.
Efflorescence is a temporary condition, and does not affect the functional properties of the product.
Efflorescence is a nuisance not only to manufacturers of concrete products but also to those involved in their specification and usage. Wind and rain will gradually remove the deposit and the true colour of the tile will be restored.
Causes of efflorescence
Concrete consists of sand, gravel, cement and water - with the cement being produced by burning alumina and lime together with other elements. Water in the form of rain, condensation or dew dissolves part of the lime. A barely soluble white film of lime, is created by this chemical reaction and is seen on the surface of the tile when the water evaporates.
How is efflorescence removed?
The natural process of weathering (e.g. rain water washing over the tiles), will wash the chalky deposit away, and the true colour of the tile will be restored.
Can efflorescence be removed artificially?
A diluted acid mix can be applied as a short-term measure. It is, however, the recommended and accepted practice to allow nature to remove the deposit.
Can efflorescence re-appear?
In some instances, efflorescence may recur temporarily.
Since the lime content of any concrete product can vary and the weather conditions can also differ, the level of the lime deposit on the surface can also fluctuate considerably. Efflorescence is a natural phenomenon and a temporary condition only.
Can efflorescence be prevented?
MONIER Roofing is constantly running tests with various manufacturing processes and weathering systems in order to reduce the likelihood of efflorescence occuring. However, at present, there is no economically viable method for reliably preventing efflorescence.