Process for making gypsum board having improved through-penetration strength

A process for making gypsum board having both front and back faces comprising a high density gypsum layer overlaying a lower density, foamed gypsum core comprising the following steps:

• (1) feeding a newslined paper sheet material to a gypsum board manufacturing line;
• (2) feeding an open mesh scrim material selected from fiberglass scrim and plastic scrim to the gypsum board manufacturing line;
• (3) forming a trough with said newslined paper sheet material and said scrim material which are fed from separate lines and are not aligned until after contact with a high density calcium sulfate hemihydrate slurry;
• (4) depositing a high density calcium sulfate hemihydrate slurry, having a density in the range of about 45 lbs./ft.3 to about 60 lbs./ft.3, in the trough between said newslined paper sheet material and said scrim material and into contact with said paper and scrim;
• (5) compressing said paper sheet material, said scrim material and said high density hemihydrate slurry whereby said scrim material is encapsulated in said calcium sulfate hemihydrate slurry to form a laminated paper/scrim/hemihydrate slurry;
• (6) passing the laminated paper/scrim/hemihydrate slurry to a gypsum board forming station;
• (7) depositing a foamed, lower density calcium sulfate hemihydrate slurry, having a density in the range of about 10 lbs./ft.3 to about 40 lbs./ft.3, on top of a high density, calcium sulfate hemihydrate slurry, which has a density in the range of about 45 lbs./ft.3 to about 60 lbs./ft.3, said high density, calcium sulfate hemihydrate slurry being carried on a manila facing paper;
• (8) at said board forming station, bringing said laminated paper/scrim/hemihydrate slurry which was compressed in step (5) into contact with said foamed, lower density calcium sulfate hemihydrate slurry which was deposited on the high density, calcium sulfate hemihydrate slurry in step (7);
• and
• (9) passing the paper sheet materials with the scrim and both high density and lower density calcium sulfate hemihydrate slurries there between along the manufacturing line until they are sufficiently cured to the point where they can be cut to length and passed to a kiln for final curing.