People regularly ask me the question: How to choose a notched trowel for laying ceramic tiles ? With this topic, I propose to analyze this issue in detail and provide recommendations. The choice of notched trowel is critical for correct application of the adhesive. The number of the notched trowel determines the glue consumption. The most commonly used spatulas are C4 (for ceramic tiles), C3 (for glass mosaics), A2 (for elastic coatings), B1 (carpets). More detailed information (sizes and shapes of trowel teeth, as well as their pictures) about notched trowels can be found in TKB-Technical Briefing Note 6 "Dimensions of trowel teeth for laying floor coverings, timber floors and tiles".
The main shapes of spatulas: triangular, rectangular, rounded. The shape of the spatula is determined by four parameters: a - tooth width; b - distance between teeth; c - tooth height; Ɣ - angle between the edges of the teeth.
Choosing the right spatula avoids:
1. Increased glue consumption .
In case of increased glue consumption, its hardening time increases and in most cases is not observed. This results in wasted time, potential for bubbles, deformation of coatings and/or adhesive protruding around the perimeter of the tiles. 2. Glue consumption is too low . If not enough glue is applied, the open time will be reduced. The quality of coating adhesion decreases. Shrinkage may also occur.