Before application, and especially on soft biscuit wall tiles, the tiler needs to dampen the joints where he intends to grout. This extra moisture slows the hydration process. With soft biscuit tiles, the body of the tile soaks up the moisture in the grout. With incorrect hydration, the grout will not cure or dry correctly and the result is powdery or crumbly grout.
If the grout is not mixed thoroughly, patches of grouted areas on the wall or floor will end up powdery or crumbly or even discoloured and patchy.
The use of a rubber squeegee (grout float) and a firm sweeping action across the joints ensures that the grout is compressed into the joint and completely fill the joint without voids. Incorrectly applied grout will be unserviceable and is likely to crack and fall out over time.
Grout has a shelf life of about 12 months from the date of manufacture. After this time it is likely to go powdery and is unsuitable for use. At Beaumont Tiles, we turn our stock over continually and grout is not packed with the job until the day before delivery to ensure fresh stock is delivered.
So What Can I Do Now?
The only way to rectify this problem is to scrape out the grout and replace it. This is done by using a grout rake (a small, cheap tool available at all Beaumont Tiles stores). Once the joints are clean, apply the correctly mixed grout.
Check out our guide on how to grout tiles for more information.
If you are re-grouting, Beaumont Tiles recommends using a Grout Additive in the mix. This enhances the grout to make it more flexible, more impervious to water and easier to clean than standard grout.
Note: Never grout the internal corners between two walls or the internal corner where a wall and floor meet. Movement and different rates of expansion and contraction will cause these joints to crack and fail. Silicone must be used in these places.