Three different hardeners (ammonium chloride, ammonium sulphate, and aluminium sulphate) were added to the UF resin. 0.85 wt% the hardener (10 wt% water solution) for the surface layers and 2.5 wt% the hardener (25 wt% water solution) for the core layer based on the solid content of the UF resin were added in the resin. The chips were placed in a blender and sprayed with urea formaldehyde. 1 wt% paraffin (32% water solution) based on the solid content of the UF resin was used as a water repellent chemical in the manufacture of particleboards. As a formaldehyde scavenger, 1 wt% of urea (10 wt% water solution) based on the solid weight of the UF resin was added to resin in the manufacture of the some particleboard types given in Table 1. The layer composition of particleboards was designed to consist of 34% chips at the face layer and 66% at the core layer, and the target density of the particleboards was 0.63 g/cm3. The mats were then subjected to hot pressing. The boards were pressed under 2.5 N/mm2 pressure, at 225 °C, for 100 s. At the end of the press cycle, the board was removed from the press for cooling. The particleboards having dimensions of 2800 mm × 2100 mm × 18 mm were produced for each type of formulation. A total of 24 particleboards, 2 for each type of formulation, were produced (Table 1). Prior to the tests, the samples were conditioned in a climatized room at 20 °C and 65% relative humidity.