Castoro mattresses are manufactured from hexagonal woven steel wire Mesh Type 60, commonly referred to as double twist wire mesh as per SANS 1580:2005. The Castoro mattresses are filled with rock at the project site to form flexible, permeable, monolithic structures for river bank and scour protection, channel linings for erosion control and underwater pipeline protection.

The steel wire used during the manufacture of the mattress is heavily zinc coated, Class A as per SANS 675:1997. If required, a PVC coating is extruded over the galvanised wire to provide added protection for use in aggressive environments such as, acidic soils and water, salt water and in water carrying a high abrasive sediment load. The PVC coating has a nominal thickness of 0,5 mm. The properties and tolerances of steel wire and mesh are shown in Tables 1 and 2.

The base, diaphragms, front, end and sides of the Castoro are manufactured from one continuous panel of mesh. The base is folded onto itself at 1,0m intervals to form double diaphragms that are automatically secured with spirals, prior to folding up the sides and securing to the diaphragms. To reinforce the unit, all mesh panel edges are selvedged with a wire having a greater diameter than the mesh wire.