- INTRODUCTION
- In 1972 Ceramic Tile Institute issued Field Report CTI , "Quarry Tile--Stain
Prevention". The title was changed to "Unglazed Tile - Stain Prevention" because
we have found the procedures workable on almost all unglazed tile. Little has
developed for CTI to do other than continue using this field report. Therefore,
it is referenced to be considered part of the paper- work for this subject.
- Ceramic Tile Institute has not previously issued a field report regarding
stain prevention of glazed tile. With use of colored grouts many glazed tile have
presented a real challenge for the tile contractor. Therefore, the content of
this field report will be more on glazed ceramic tile and on the use of colored
grout with the glazed tile.
- DISCUSSION
- Ceramic Tile Institute has not previously issued a field report regarding
stain prevention of glazed tile. With use of colored grouts many glazed tile have
presented a real challenge for the tile contractor. Therefore, the content of
this field report will be more on glazed ceramic tile and on the use of colored
grout with the glazed tile.
- The tile industry has adopted the colored grout and we expect to perform miracles
with it. One of the miracles we expect is to grout an installation and have the
colored grout turn out to be exactly the same shade throughout.
- There are many variables that have an effect on the finished shade of colored
grout. The best results are obtained by treating all of the grout over the entire
installation the same. This means:
- Waiting 48 hours before grouting a thin-set installation and waiting 72 hours
before grouting a mortar bed instal- lation, the waiting period is to allow the
wetter areas of the installation to dry out and have them uniform so that the
grout will react the same in all joints. For maximum color uniformity when dry
porous bodied tile is used, all installations, especially a mortar method, should
be allowed to dry thoroughly before grouting. The smaller the joint the more critical
this is, as the smaller volumes of cement grouts are more inclined to show the
results of uneven initial drying, i.e.: splotchy or mottled appearance.
- Keeping the width and depth of all of the joints the same prior to grouting.
- Mixing all of the grout used with the same amount, and a minimum amount of
water, and mix it all the same way.
- Planning your day's work so the next day's grouting does not join in the center
of conspicuous areas. Stop and start evenly in a corner. Different temperatures
from one day to the next and difference in humidity from day to day can change
the shade of the grout.
- Using water to cure the grout to maximum hardn ess. It does not take long,
when working in the construction trades, to realize how much effort goes into
curing concrete, in order to make it hard and strong. The necessity to wet cure,
is true of all portland cement products. Curing our comparatively thin lines of
grout is even more critical than curing concrete. Common sense should therefore
tell us that you cannot take a dry surface, bond dry tile to it having sixteen
percent or more absorption, grout it, and then walk away and leave it uncovered.
What little moisture was present evaporates, leaving a chalky and discolored grout.
There are procedures that must be followed to prevent this:
..Saturate the joints and wet the surface prior to placing the grout on the tile..
The -grouting of a wet surface is easier, and the finished tile will be much cleaner,
com- pared to placing the grout on a dry surface. The water in joints will start
and help maintain, the hydration of the portland cement grout.
..Use ad-mixes recommended by the manufacturer of the grout being used. Many contractors
use Anti-Hydro in their grout. First an Anti-Hydro water is made, one part Anti-
Hydro to five parts of water. The Anti-Hydro water is then used to wet the grout.
IMPORTANT--Get the permission of the grout manufacturer before using the Anti-Hydro,
the manufacturer may recommend a different ad-mix.
..ANSI A108.5 requires, "Cure both portiand cement and Dry-Set grouts by keeping
damp for at least 72 hours. Add dampness as needed. Covering with paper facilitates
curing of grout".
- Grout all areas of the installation with the exact same procedure. The most
cons istent color can be obtained by using a firm rubber float to effectively
fill and compact the grout joint. Remove the bulk of excess material from the
surface of the tile with a rubber float not a sponge.. As soon as grout firms
up enough to be worked without being pulled from the joint, use a pad of cheese
cloth dampened with clean cool water to clean tile surfaces and bring grout to
finish contour and texture. Use a minimum amount of water. 'Keep water clean and
cool. When haze appears, polish installation with dry cheese cloth. A sponge is
not recommended for grouting.
- Another miracle ex ected is to grout dark tile with light grout or light tile
with dark grout and not have it stain any of the current tile manufactured.
- If contrasting colors are to be used in grouting the only foolproof way to
prevent staining is to paraffin wax the tile.
- Grout releases have not been consistent in preventing the tile from being
stained.
- CONCLUSION
- The better understanding we have of the materials we use the better job we
will be able to do with them.
- Most unglazed tile will stain under use unless treated to prevent the staining.
Ste Field Report, "Unglazed Tile - Stain Prevention'li, CTI 72-2-2 (R-85).
- Many glazed tile are prone to be stained by the grouting and some adequate
method must be used to prevent it.
- Additonal field reports recommended on this subject are:
- "Grout Joints-Color-Width-Texture-Strength-For Ceramic Tile Floors", CTI 73-7-2.
- "Portland Cement-Aggregates-Plasticisers and Water", CTI 73-2-7 (R-85).
- "Graded Extra Fine Sand Aggregate", CTI 73-1-3
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