Grouts and Grouting
Apart from the specialist materials discussed below,
the general grouts used are essentially cement based with special additives to
ease application, improve bonding, repel water and reduce shrinkage after
application. For flooring and external applications, although ordinary sand
and cement can be used for grouting natural stones etc, specialist grout
materials are considered preferable even for external applications.
The majority of the popular grouting materials used by
professionals and the DIY alike are supplied in powder form and are simply mixed
with water to produce a paste.
There are a very wide range of these materials
available from a number of suppliers. These materials are widely available
through reputable suppliers.
The notes below provide proposals for
Grout Selection and
Application procedures for general purpose
cement based grouts, This page is split up into the
following sections:-
Considering
the normal conditions for wall and floor tiling, the major factors influencing
the choice of grout are colour, grout width and possibly setting time.
If your tiles will come into contact with water, or
hygiene areas such as kitchen worktop food preparation areas, tiled areas which
are subject to public hygiene restrictions (BS) or need to be acid or alkaline
resistant, an epoxy-based grout must be used. Epoxy grouts should also be used
for metal tiles, and even tiles with a metal substrate. For commercial
applications, an epoxy grout may be specified for other specific reasons. It is
also recommended that epoxy grout is used in shower bases in particular to
avoid the possibility of water migration behind the tiles and causing problems.
These grouts are significantly more expensive that the
general-purpose grouts, and greater care must be used when removing grout
residue a s any epoxy left to cure on the surface of the tiles will be extremely
difficult to remove -special grout remover may need to be used to clean the
tiles afterwards. It is recommended that the services of a professional with
experience of epoxy grout systems should be used for this type of application.
You may also find that the professional will often specify a manufacturers
material to use, as the characteristics and working methods tend to differ from
manufacturer to manufacturer.
Note that suitable protective gloves should be worn
whenever using epoxy grout systems as it is not advisable for this type of
material to come in direct contact with the skin.
The following mixing and application method is
applicable to 'slurry grouting' which is the easiest and best method most
commonly used where the tile surface can be easily cleaned afterwards. However,
if you are laying a highly marked natural stone or terracotta (rough side up),
where you do not wish to fill the 'indentations' etc. with grout, it is more
appropriate to mix the grout to a thick 'dryish' paste, and use a conventional
pointing technique as used for normal house brickwork.
All necessary movement joints such as the surrounds of
baths etc. should either be initially filled with suitable flexible
mastic/silicone, or protected to ensure excess grout is not allowed to
accumulate and set.
If applying grout to natural stones or unglazed tiles,
ensure that an appropriate coating of sealant has been applied before grouting
to aid cleaning of the tile surfaces.
Always ensure that mixing containers and tools are
clean and free of previous grout mixes.
Always mix the grout with clean water free of
contaminants such as salt etc.
Do not mix grouts of different types and manufacturers,
and do not mix with cements or limes etc.
Read the manufacturers instructions to ascertain the
‘pot life’ (working time) and bear this in mind when mixing up a batch of grout.
Ensure that you are able to apply all the material mixed prior to the pot life
being exceeded.
Before grouting, check that the tiles are well fixed,
and in the case of fixing with traditional mortar, that the minimum waiting
period of 7-10 days has passed as this allows for the removal of the moisture
and therefore the soluble salts. The joints to be grouted must be dry, clean and
free of dust and foreign matter. They should be clear for at least 2/3 of the
depth of the tile – any excess mortar or adhesive must be removed.
Whilst
stirring pour the dry powder mix into a clean plastic bucket containing a small
quantity of clean water (refer to manufacturers instructions for details of
quantities). Mix until a smooth creamy paste is obtained. If available, use a
slow speed mixer (maximum 150 rev/mm) to prevent the excessive formation of air
bubbles.
Leave the mix to stand for 2-3 minutes and then remix
briefly before use.
The working time of the grout changes between different
types and manufacturers, varying from anything between 30 minutes to a few
hours.
If the grout starts to set before applying it to the
tiles, do not add more water, simply discard and clean out the mixing container
before making up another batch. After completing your work, ensure that any
material left is removed from your container, and that the container is cleaned
before the grout has cured.
WARNING
: If you are grouting over metallic tiles, great care should be taken not to
cause abrasion of the glaze with the grout mix. Although the metallic glazes
featured within our products should not pose any problems, there are some much
'softer' glazed tiles available on the market - particularly bright gold. In
some cases, these are supplied with a protective film over the surface, in which
case, this should not be removed until after grouting has been completed.
Always use the same method of working to obtain uniform
results. Where the tiles are absorbent or the ambient temperature is very high
lightly dampen the surfaces of the joints with a wet sponge before applying the
grout.
Fill the tile joints with the grout paste using either
a hard rubber float or squeegee without leaving voids or gaps.
Remove the excess grout from the surface by drawing the float diagonally across
the joints whilst the paste is still fresh.
Leave the paste to firm up in the joints until it is no
longer plastic.
Clean off the surplus grout with a damp hard cellulose sponge working diagonally
across the joints without applying any pressure. Rinse the sponge frequently
preferably using two buckets of water; one for removing the surplus paste from
the sponge and the other for just clean water for the final rinsing of the
sponge and moistening new ones. Use a special grouting sponge – the proverbial
bath and household sponges rapidly fall to pieces become quickly overloaded with
grout.
The final cleaning of the residual film of grout powder from the surface of the
tiles should be carried out using dry waste paper or a clean dry cloth after the
grout has set.
If the cleaning off is carried out too quickly (when the paste is still plastic)
it is possible that the grout will be partially removed from the joints. On the
other hand, once the product has set hard, cleaning by mechanical means will be
necessary which is very difficult and likely to cause damage to the surfaces.
Do not allow traffic onto the tiles, or subject to
excessive water or extremes of temperature until the grout has fully cured –
refer to the manufacturer’s instructions. If the material being used is a
natural stone, terracotta or unglazed tile, then after cleaning, apply one or
more further coats of sealant and finish with appropriate polishes etc. as
applicable.
Again, read manufacturers instructions, but generally,
cement based grout can simply be cleaned from tools etc. with water, and cleaned
from the hands with soap and water. Epoxy grout should not be allowed to harden
and should be removed from all of your tools while it is still in a liquid
state. Suitable protective gloves should be worn whenever using epoxy grout
systems as it is not advisable for this type of material to come in direct
contact with the skin.
