Method for steam pressing composite board having at least one finished surface

A method for making a composite wood product, comprising the steps of:

• forming a mat comprising wood particles treated with uncured binder;
• placing said mat in a press cavity defined between first and second press platens;
• closing the press cavity;
• consolidating the mat fully by moving at least one of the first and second press platens toward the other of the first and second press platens to a final compression position;
• supplying a first quantity of steam to the mat through at least one steam port in the first press platen and venting said first quantity of steam from the mat through said at least one steam port in said first press platen, said first quantity of steam supplied at a pressure and for a period of time and vented such that excess air is purged from the mat;
• and
• supplying a second quantity of steam to the mat through the at least one steam port in the first press platen, the second quantity of steam supplied at a temperature and pressure sufficient to cure the binder.

A method for making a composite wood product, comprising the steps of:

• forming a mat comprising wood particles treated with uncured binder, the mat having opposite first and second sides;
• consolidating the mat to a final thickness in a sealed press cavity;
• supplying a first quantity of steam through said first side of the mat to at least that portion of the thickness of the mat that is not occupied by a quantity of excess air, said first quantity of steam supplied to said portion of the thickness in a pressure and for a period of time sufficient to raise the temperature of said portion of the mat to at least 100° C.;
• venting the mat through said first side such that the quantity of excess air is purged from the mat;
• and
• supplying a second quantity of steam through said first side at a temperature and pressure sufficient to cure the binder throughout the thickness of the mat.

A method for making a composite wood product, comprising the steps of:

• forming a mat comprising wood particles treated with uncured binder, the mat having opposite first and second sides, a moisture content and an air content;
• consolidating the mat to a final thickness in a sealed press cavity;
• supplying a first quantity of steam through said first side of the mat to a first portion of the thickness of the mat that is adjacent to the first side of the mat, said first quantity of steam supplied to said first portion of the thickness in a pressure and for a period of time sufficient to raise the temperature of said first portion of the mat to at least 100° C.;
• heating a second portion of the thickness of the mat adjacent to the second side of the mat by convection, the heating sufficient to convert at least a portion of the moisture content in the second portion of the thickness of the mat to steam;
• venting the mat through said first side such that excess air is purged from the mat;
• and
• supplying a second quantity of steam through said first side at a temperature and pressure sufficient to cure the binder throughout the thickness of the mat.