1. The grout should be prepared in a clean bucket which will minimize the risk of efflorescence. It is best to prepare the grout in small portions, about 2kg in order to use it within a short time period. The grout should have the consistency of wet sand, like from the bottom of a sandbox: when you press it a small ball is formed and water does not leak out of it and when you drop it from a low height it breaks against the floor.
2. The grout should be applied with a spreader (a joint trowel) for clinkers and natural stones. It is best to get a spreader with the highest hardness which bends the least when pressed and which returns to the initial position. The optimal width of grout is about 10 mm.
3. A small amount of a prepared mortar should be put on a rectangle, 30 x 15 cm in size and made of a material which does not absorb water, for instance, galvanized metal sheet or plastic. Using a spreader, we apply the right amount of grout in the slits between tiles and on the area no bigger than 4 tiles vertically and 4 tiles horizontally. Next, press firmly the grout and get rid of the excess of the material at the same time.
5. Pressing the grout too strongly may push it out of the slit. The grout applied and even slightly pressed but left for 24 hours hardens and attaches to the foundation. It gains resistance after at least 21 days. Grouting the parts of walls is best done within one day so the colour of the grout is the same.