Taking the example of the pvc panel in the hand can determine the strength and quality of the material from which it is made.  Count the number of cross bridges (stiffeners) than their bigger, the better.  Take the panel over the edge with two fingers and squeeze force (see Fig. 1), pvc panel should not burst or flattened, permitted only a slight deformation.  Try 3-4 times the extreme bend of the back surface of the corner platikovoy panel (see Fig. 2).  If she broke down and did not break, the quality of the material is good and this plastic panel has a high durability.  If cracked and broken, then the quality is low, because  added to the mixture of a lot of chalk, this pvc panel will not stand high loads on the surface and the more random attacks.

           

 Visually, we can estimate the geometry of the panel, PVC and quality of the front surface.  When mounting the pvc panels the seam between the panels must be almost not noticeable visually and by touch.  High-quality plastic panels are joined tightly together, forming a single picture.  The surface of the plastic panels must be flat, smooth and without the stripes formed by the ribs.  The thickness of the front surface of the wall panels, PVC should be thicker than the rear.