Gypsum Plaster Board
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| COMPOSITION | Gypsum, water ( possible addition of silicones, starch and covered with a layer of thin cellulose cardboard).contains 32.5% calcium oxide, 46.6% sulfur trioxide, and 20.9% water |
| PAPER SURFACE | Several types of paper covering are used on gypsum boards, depending on the board type and exposure. Surface that will be exposed (faces) for field decoration, such as painting, are usually cream coloured, sized, and calendered paper, sometimes called “cream paper”. Faces and sides opposite the faces, which are called backs, and which will be covered by other materials, including other gypsum board in multilayer installations, have traditionally been covered with gray, unsized, and uncalendered paper, called “gray paper”. |
| STREAK | white |
| HARDNESS (MOHS’ SCALE) | 1.5 – 2.0 |
| DENSITY | 2.2 – 2.4 g/cm3It is slightly soluble in water. |
| CLEAVAGE | Perfect (If a mineral breaks easily and cleanly in one or more directions) |
| COLOUR | Common colour: white, colorless, yellowish white, greenish white, or brown. |
| FRACTURE | Fibrous – Thin, elongated fractures produced by crystal forms or intersecting cleavages (e.g. asbestos). |
| FIRE | Tested to BS 476: Part 7, the gypsum wall board shall have a class 1 surface of flame. |
| THERMAL CONDUCTIVITY | Gypsum has a very low thermal conductivity: 0.16 W/m K. |
| THERMAL RESISTANCE (R) | 9.5mm thickness= 0.059 mm²K/ W12.5mm thickness= 0.078 mm²K/ W15.0mm thickness= 0.093 mm²K/ W19.0mm thickness= 0.118 mm²K/ W |
| FINISHES | Paint and textured finishes. |
| OTHERS | Good moisture regulator. Products can often be recycled if they do not have added filling. |