Most nails are made from wire, usually mild steel, although other metals are used for specific situations, like copper nails for boat building. Most nails are left bright but they may be hot dip galvanised, nickel, zinc or cadmium plated for use in areas of high moisture. Galvanised nails are for exterior use.

Nail head type

Purpose
Bullet or jolt head
General purpose use in construction or cabinet making
Flat head
12-150mm long
For joining thin materials to timber and softwood frames. The width of the head gives greater holding power.
Roofing nail
75-150mm long
Galvanised nail for corrugated roofing with a spring washer under the head and may also have a neoprene washer under this.
Clout
12-50mm long
Galvanised nail, a shorter variety of the flat head. They have a much larger circular head and are used for fixing thin sheet material.
Panel pin
10-50mm long
Small, slender nails with a conical shaped head for finer work. They leave a very small hole when punched.
Brad

A smaller version of the panel pin.

Other types of nails include staples, escutcheon pins, cut tacks and corrugated fasteners.

The point of a nail is pyramid shaped to force the fibres apart. This may split the timber sometimes. Blast types may be used for fibrous cement sheet - they punch a hole through it.

The thickness or wire gauge of a nail is stated in millimetres. The shank may be square or round. For greater holding in softwood, end grain or chipboard, use an annular, helical or twisted shank nail.

When ordering nails, state the length and gauge in millimetres, head type, material the nail is made from and the quantity in grams or kilos. A typical nail order would be 2kg of 100mm x 3.75mm galvanised mild steel jolt-head nails.

The length of a nail is important to gain the maximum hold in the timber. When nailing across the fibres, the nail should be 2-2.5 times the thickness of the timber and when nailing into end grain it should be 2.5-3 times the thickness.