(450 mm in length and 450 mm in width). Forty millimeter-thick RSTIB mats were prepared with a target density of 200, 250, 300 and 350 kg/m3. After forming, the mats were loaded into a press.Two pieces of Teflon sheets were placed on the top and bottom surfaces of the mat to prevent the boards from sticking onto the hot plates during pressing. To improve the production and quality of the thick boards, a CGM-30 high frequency (HF) press was chosen.