Notched Trowel

A notched trowel is the main tool in construction for floor and wall adhesives and ceramic tile mortars, and works with both water-based and the solvent-based adhesives and mortars (Fig. 3). It is also used for a simple manual application of two components, epoxy or polyurethane adhesives, on flat surfaces, because these trowels are easy to clean. 

Trowel application is convenient only for large and flat surfaces such as floors, sandwich panels, walls (with a suitable high viscosity to avoid dripping). It is used to apply heavy coatings from 200 g/m up to several kg/m.  

Sometimes the adhesive is first troweled on the surface with a flat large trowel in a rather thick coat and then the notched trowel is used to adjust the thickness by combing this flat coat. 

The depth and number of teeth or notches vary according to the amount of adhesive which should be applied. 

After the trowel passed over the adhesive, it leaves ribs on the surface, and the height of these ribs may facilitate filling some gap between the two substrates. 

---

Fig. 1. (Top) Typical V-notch spreader used with tile-board adhesives. (Bottom) Typical notched trowel used to apply floor mastic.

Chlorinated solvent systems. Most adhesive-installed wood flooring today utilizes this type of material. They are nonflammable because they utilize 1,1,1-trichloroethane or other chlorinated solvent with a base such as butadiene-styrene rubber. High strengths are achieved, yet the material remains sufficiently resilient to allow normal expansion and contraction of the flooring and the substrates without delamination. In virtually all cases the adhesives are applied by notched trowel. 

Also, the recommended notched trowel for the installation must be used to achieve the proper laydown. 

These systems can be troweled on or extruded through a caulking gun. Little operator skill is required. Since the thixotropic nature of the paste prevents it from flowing excessively, application is usually clean, and not much waste is generated. With trowel application, the depth of notch and the spaces between them help regulate the amount of adhesive applied. Shallow, rounded, and closely spaced notches are often used with lower-viscosity adhesives to allow the lines of adhesive to flow together and form a continuous, unbroken film. 

Incorrect Amount. All too often an attempt is made to install wall or floor covering with an insufficient amount of adhesive. Even if the trowel notch size is correct, it may be partially clogged, or held at the wrong angle, or worn down from long use on concrete. 

Several factors may cause poor bonds as a result of excessively dried adhesive the size of the bead from a cartridge the size of the notches on the trowel failure to wet the substrates ambient temperature too high and humidity too low and too long a waiting period before assembly. 

---