Cross Recessed Countersunk Drywall Screw

Cross Recessed Countersunk Drywall Screw

The term "drywall screw" originates directly from English. Its distinctive appearance feature is the bugle head. Drywall screws fall into two categories: double-thread fine thread drywall screws and single-thread coarse thread drywall screws. The major difference between them lies in their thread design. The former adopts double threads and is used to connect gypsum board to metal keels with thickness no more than 0.8 mm. The latter is designed for joining gypsum board and wooden keels.

Drywall screw series constitutes one major category within the full fastener product line. These products are mainly applied for installing various gypsum boards, lightweight partition walls and suspended ceilings. Black phosphated drywall screws form the basic product line, while blue-white zinc plated drywall screws serve as a supplementary option. Both types have similar application scope and purchase price. Slight differences exist: black phosphating delivers certain lubricity and superior penetration rate (penetration speed into steel plate of specified thickness, a quality evaluation indicator); blue-white zinc plating offers better rust resistance and a lighter base color, so it is less prone to absorbing paint color after coating and decoration. Blue-white zinc plating and yellow zinc plating provide nearly identical anti-corrosion performance; selection depends merely on construction habits or customer preferences.

Single-thread coarse drywall screws feature wide threads and correspondingly faster tapping speed. Meanwhile, their penetration will not damage the internal structure of wood after driving in, so they are more suitable for mounting wooden keels compared with double-thread fine thread drywall screws.

In overseas construction industry, great attention is paid to selecting appropriate fasteners. Single-thread coarse thread drywall screws act as an alternative to double-thread fine thread drywall screws and perform better for wooden keel connections. Double-thread fine thread drywall screws have been widely used in China’s domestic market for a long time, so it will take time to change construction habits.

Three common coating processes for drywall screws: Drywall screws are normally finished by electroplating, hot-dip galvanizing and mechanical plating (the most widely adopted of the three). A uniform protective layer is formed on the surface of assembled screws for corrosion protection. After treatment, surface aesthetics are greatly improved. Apart from enhanced corrosion resistance, the coating features dense structure, expanding the applicable range of fasteners and bringing high adaptability. Many fastener manufacturers adopt these coatings for drywall screws and other fastener products.

1. Electroplating: Metal is deposited onto fasteners in aqueous solution by electric current. The process can be adjusted as required to achieve tight bonding between coating and substrate.

2. Mechanical plating: Mainly using zinc powder, metallic coating is formed on fasteners via combined physical and chemical reactions.

3. Hot-dip galvanizing & passivation: Fasteners are immersed in molten zinc bath at about 510℃ to form alloy coating. This coating improves the performance of high-strength bolts and is favored by numerous fastener manufacturers.