How to Grout Wall Tiles
If it is only a week old, you should get the tiler back to fix it, free of charge. If you do want to do it yourself, scratch out the damaged/cracked sections, ro get below the cracked level. The easiest thing to use is a flat-blade screwdriver of the right width. Wet the damaged sections with a wet sponge. This will stop the older grout sucking too much water out of the fresh lot, thereby drying that out too quickly. Mix no more than half a cup of grout at once, to a thick paste. Apply it with a baking spatula, at an angle to the grout-lines, to work it well in. Scrape off the excess from the tiles. After about 20 or 30 tiles, go over the finished ones with a rough flat sponge, only very slightly damp. If your mixed grout starts to go grainy, discard it and make more. You can’t thin it again, as it changes chemically. Next day when it is dry, use a dry sponge, held very flat, to polish off the thin film of grout still left on the tiles. This will also make the tiles very shiny. Don’t l