Efflorescence – Causes
& How to avoid it!
As manufactures of quality cement based tile
adhesives and grouts, every so often we will
have a client contact us asking “ Why is my
grout patchy” or “The colour is lighter than what
I chose” or “ A white residue has appeared over
the grout”. The above statements are typical
signs of Efflorescence.
What does
Efflorescence look
like?
Efflorescence is generally described as a
whitish powder or crusty deposit on the surface
of the grout joint. Efflorescence can appear as
patches or all over the entire grouted area, or
just isolated to one area depending on various
causes.
Efflorescence is more prevalent in darker
colours simply because the white salt residue is
highlighted on a dark background (grout joint).
Efflorescence occurs in all cement-based
products and not restricted to grouts.
What causes
Efflorescence?
Efflorescence can occur due to multiple factors;
usually the catalyst for Efflorescence is climatic
or excessive amounts of water.
Climatic– Efflorescence does occur more
regularly in the cooler months. This is due to the
water that is used to mix grout remains in the
grout for a longer than desired period, enabling
the soluble salts (free lime) in the cement to
easily migrate to the surface.
Mixing:
More commonly Efflorescence is promoted
when excessive amounts of water is added to
the grout upon mixing or even on clean up. Eg.
10kg bag of RLA Coloured Grout should only be
mixed using 3-3.2L of clean water, no more!
When overwatering occurs, the mixture is so
saturated with water, this will introduce air
entertainment and all soluble salts within the
cement in the grout easily migrate to the
surface.
Cleaning:
Proper cleaning of excess grout residue is
essential to achieving the desired grouting for
your floor. Once the grout has been mixed and
installed in accordance with the manufacturer’s
instructions, the following cleaning method is
recommended in-order to achieve grout
satisfaction.
1) Using a clean sponge apply water to the
sponge then drain it thoroughly until the sponge
is damp not dripping wet.
2) Avoid over cleaning, once most of the grout
residue has been removed from the surface of
the tiles, stop cleaning, don’t worry about minor
residue that may be left behind this should
clean up nicely the next day by buffing with a
dry cloth or rag.
3) Avoid using wet cleaning methods like wash
boy’s, these leave too much water on grout
joints, which then re wets the grout causing a
candle wick effect drawing up the salts from the
Substrate, adhesive and grouts to cause
Efflorescence.
4) When using RLA Coloured Grout on glossy
tiles, there is no need to over clean, as this will
only introduce more water onto the surface of
the grout.
5) Remember minor grout residue left on the tile
will easily clean up the next day using a soft dry
rag or cloth.
How to avoid
Efflorescence in
Cementitious Based
Grouts?
Efflorescence is an issue, which has no
guaranteed solution; Preventative measures will
assist in reducing Efflorescence. What to Do?
Surface preparation:
1) If tiling on concrete, ensure that the substrate
is fully cured before any tiling can commence.
2) If tiling over sand cement screed allow the
screed to cure for 7 days before tiling. Residual
moisture in cement will evaporate and may
cause Efflorescence to occur.
3) Check for rising damp.
4) If substrate has higher levels of moisture or is
still “green”, installing an epoxy moisture barrier
is highly recommended.
5) Allow Tile Adhesive to cure before grouting
6) Correct mixing of RLA Coloured Grout, 33.2L of water.
7) Where possible, always use a Synthetic or
Epoxy grout product that has no Portland
cement, these products will not effloresce.
In order to greatly reduce the Efflorescence
in RLA Coloured grouts, the grout must be
mixed correctly. Consistency should be that of
toothpaste and hang on the grout squeegee.
Any grout including RLA Coloured Grout that is
incorrectly mixed where too much water is
added, making it into a fluid like consistency,
increases the chances of Efflorescence
occurring.
RLA Coloured Grout is a highly modified grout
that has specialised additives that help to
reduce the occurrence of Efflorescence. RLA
Coloured Grout performance has been
thoroughly examined by reputable independent
testing companies.
Results show that RLA Coloured
Grout complies with Australian and International
standards AS/ISO13007.3-2013, as a CG1 type
grout.
This means that RLA Coloured Grouts are
considered to be of extremely high
performance.
The classification CG1 comes after rigorous and
repeatable testing has been completed.
Remember
Efflorescence is due to excessive amounts of
water, humidity, cooler climates and dampness
in substrate or adhesive. Tilers should take care
to force the grout deep into the bottom of the
joint. If Tile Adhesive has filled part of a joint,
rake the joint out before grouting.
Try to eliminate the above factors, as this will
greatly reduce Efflorescence.