METHOD FOR STEAM PRESSING COMPOSITE BOARD HAVING AT LEAST ONE FINISHED SURFACE

IN A METHOD FOR MAKING COMPOSITE WOOD PRODUCTS HAVING A MARKET READY FINISHED SURFACE, A MAT IS FORMED OF WOOD FIBERS TREATED WITH A BINDER. THE MAT IS LOADED INTO A PRESS CAVITY FORMED BETWEEN TWO PRESS PLANTS. TEH FIRST PRESS PLATEN IS A CONVENTIONAL HOT PRESS PLATEN FREE OF PORTS. THE CONVENTIONAL PLATEN CAN BE SMOOTH OR PATTERNED TO EMBOSS THE FINISHED SURFACE ON THE PRODUCT . THE OTHER PLATEN HAS STEAM INJECTION PORTS. THE PRESS CAVITY IS CAPABLE OF BEING SEALED. THE MAT IS FULLY CONSOLIDATED. HEAT CONDUCTED FROM THE FIRST PRESS PLATEN TO A FIRST SIDE OF THE MAT VAPORIZES MOISTURE IN A PORTION OF THE THICKNESS OF THE MAT CLOSEST TO THE FIRST SIDE CAUSING THE MOISTURE TO GREATLY EXPAND IN VOLUME . THE EXPANDED VOLUME IS VENTED THROUGH AN OPPOSITE SIDE OF THE MAT TO PURGE TRAPPED AIR FROM THE MAT. THE VAPOR EXPANSION IS VENTED FROM THE MAT THROUGH THE STEAM INJECTION PORTS, CARRYING WITH IT TRAPPED AIR AND MOISTURE. SUBSEQUENT TO PURGING OF THE TRAPPED AIR, THE PRESS CAVITY IS SEALED AND, A QUANTITY OF STEAM FROM AN EXTERNAL SOURCE IS INJECTED BY WAY OF THE STEAM INJECTION PORTS INTO THE MAT AT A SUFFICIENT PRESSURE AND FOR A SUFFICIENT TIME TO CURE THE BINDER. THE QUANTITY OF STEAM FROM THE EXTERNAL SOURCE IS VENTED FROM MAT THROUGH THE STEAM INJECTION PORTS BFORE THE PRESS CAVITY IS UNSEALED.