Grouts are no longer just white, and today can be found in a wide range of colours to enhance a specific tiling scheme. Special consideration should be given when using epoxy grouts and when grouting natural stone tiles, such as marbles, or mosaics.
Preparation techniques
Ensure that the tile adhesive has set fully before commencing the grouting process. If the grouting is undertaken too soon, the pressure applied can force the tile away from the unset adhesive and break a bond which won’t form again.
As a rule of thumb, the grout depth is normally double that of the grout width.
Avoid a really thin layer of grout as this will be less stable and will require regrouting at an early stage.
Adhesive application
Powder grouts should be mixed to a thick consistency.
Add the stated amount of water as per the manufacturer’s recommendations or else fine lines may appear in the joints, producing a less durable and weaker mix. If too little water is added to the powder grout, the mixture will be difficult to apply and may set too quickly.
By using a mechanical stirrer, the most suitable mix for the application will be achieved.
Use a rubber-faced float or a grouting trowel to completely fill the grout joint to the surface level of the tile.
Leave the grout to set to a level where it will withstand the pressure of the touch of a finger, and then smooth off with a damp sponge using a circular motion over the joints until the grout is flush, leave to firm up again and wipe with a damp sponge.
Epoxy grouts
Ensure that any surplus epoxy grout is removed from the tiled surface immediately with a sponge and clean warm water. If the excess is allowed to set, it will be very difficult to remove.
To achieve a perfect finish without smearing, apply the grout into the tile joints clear off excess diagonally across the joints with a rubber float and leave for approximately 30 minutes and wash off with damp sponge onto the joints (warm water will be more effective).
Testing
If using a coloured grout, pre-test a small area of the grout with a sample tile. If staining occurs (which may happen with terracotta tiles because they are softer than ceramic tiles), the surface should be sealed with a suitable sealer before applying the grout.
Terracotta tiles
Seal the surface and sides of the terracotta tiles, before grouting, with two coats of boiled linseed oil, or equivalent substance, to prevent the grout staining the surface, or seeping through the sides of the tile.
Pre-seal the terracotta tile even if using a cementitious grout, or else water from the grout will be sucked-out by the tile, resulting in a weak and unsightly grout joint.
Mosaics
Some mosaic tiles come with a paper face (stuck face down onto a sheet of paper), and these types of tiles should be fixed onto the background with a 4mm notched trowel taking care to line up the exposed tile edge. Once fully set on the wall/floor, the paper-face can be removed using a wet sponge.
Other types of mosaic tiles should be treated in the same way as any other size of tile, and with the same care and attention, however laborious the task because of the small size of the tile.
Temperature
For more information, contact PCI’s Techincal Services Department on 0161 794 7411