It is a whitish powder like deposit which often
appears on concrete and clay products. This deposit is a residue of a
soluble salt carried to the surface of the pavement or wall by
evaporating moisture, which leaves a dry powder or calcified deposit
A phenomenon reported as early as the
1870's, efflorescence in itself, does not affect the structural
integrity of the substrate.
|The above is an example of efflorescence
in it's worse case scenario. The residue is so great that it has the
look and feel of caked flour.
Efflorescence usually rises after
installation as a powdery substance but can also form harder patches of calcium
carbonate during the manufacturing process. The later being more difficult to
remove. Hard, definitive white lines or patches (some appear to have a slight
bluish tinge) on paving stones must not be confused with efflorescence. These
residues are "lime" and often can not be removed at all or at least without
substantial damage to the substrate. These pavers should be changed for
These salts are found in the
native soil, gravel or limestone pavement base, in the sand, aggregate, ash or
cement used to manufacture concrete brick block or paving stones.
An example of Paving Stones stockpiled
in the yard of a Paving Stone Manufacturer. You can notice the
varying degrees of efflorescence. Paving Stone manufactures accept
no responsibility for efflorescence.
Salts dissolve in
either the ground water, rain water or water added to the mix the
concrete and moves to the surface through evaporation. In basement
walls, this travel action has been measured to be as much as 600 mm.
Since the sun and warmer exterior air evaporates moisture at a
faster rate, it causes a "wicking" action that continues to draw
moisture to the exterior surface until the substrate is dry. The
efflorescence continues to surface until either the salt or moisture
supply has been exhausted - which in most salt cases occurs within
60 days - but has been known to last for many years in extreme
Most efflorescence can only be
removed with acidic solutions (such as acid rain over extended periods of time,
or acidic based efflorescence cleaners). Although most efflorescence will
dissipate with a few years of acid rainfall, STONESAVER does not recommend
waiting for this to occur before applying a protective sealer. During this
extended waiting period, the Pavement or walls could be damaged by staining,
acidic etching, freeze-thaw cycles, pitting, spalling, traffic wear and color
fading. STONESAVER recommends a minimum 60 day waiting period ("longer" if dry
weather exists) after wall or pavement installation, to allow for the majority
of efflorescence to surface, prior to product application.
Upper part of the
image is the surface cleaned to a point to show how efflorescence can
obscure the true colors making paving stones look faded.
After photo of the
Paving Stones after Cleaning & Sealing with STONESAVERs Surface Prep
and Paving Stone Sealer.
CONCRETE CLEANER & SURFACE PREP
Prep is a highly concentrated Efflorescence Cleaner which requires no
handling or pre-mixing of chemicals. Surface Prep comes complete with a
pre-attached "E-Z Sprayer" (a hose end adapter which connects to your garden
hose and disperses the Surface Prep in a cherry scented soapy solution. After a
light scrubbing, the E-Z Sprayer adapter (along with an additional hose and gun)
can be used to facilitate rinsing the cleaner from the surface. A 1 litre bottle
of Surface Prep including E-Z Sprayer adapter, weighs less than 3.5 pounds and
easily cleans up to 300 square feet. It is the most user friendly acidic based
cleaner available anywhere! After a minimum 24 hour uninterrupted drying period,
STONESAVER's Premium Sealers, Water Repellents or Paints can be applied for
surface beautification and long term protection. Remember! Sealing over an non
cleaned surface will trap in efflorescence, dirt, stains and tire tracks. Never:
seal or re-seal a concrete surface which has not been previously cleaned with STONESAVER's
Surface Prep Cleaners.