Painterwork - Painting On Iron

Painting On Iron

Iron and steel work should receive a coat of oxide paint at the manufacturer's works; additional coats are added after erection. All rust should be previously removed by means of wire brushes and paraffin or turpentine. The best paints for external ironwork are composed of oxide of iron and red lead, mixed with linseed oil. The following is an extract from the building by-laws of the municipality of Johannesburg: All structural metal work shall be thoroughly cleaned from scale and rust before painting.

Faying surfaces in riveted work shall be painted before putting them together. All surfaces of steel or iron work inaccessible after erection shall be protected as far as possible either by coating them with ` Smith's ' or other approved bituminous composition, or by filling the spaces which they enclose with lime concrete. Repainting Old Work. Before beginning to repaint work of any description it must be thoroughly cleaned. If the surface is in good condition it will be sufficient to scrub down with good soap and water and afterwards sponge and wipe dry. If the work has become rough it will often be necessary to use pumice stone to facilitate the operation of cleaning. The pumice should be cut or rubbed to a flat surface and vigorously applied with plenty of clean water. It is essential that the work should be quite dry before any paint is applied. If the old surface is much cracked and blistered no amount of rubbing with pumice will enable the workman to obtain a good ground for the new coats, and it will be necessary to remove the old paint entirely. For this purpose painters most frequently use a paint burner or torch that burns paraffin oil under air pressure. This causes the paint to soften and blister under the heat, in which state it is readily scraped off by a blunt knife. The old-fashioned grate filled with charcoal held close to the surface by means of a long handle is now not often used. There has recently been a considerable increase in the use of chemical paint removers in paste or liquid form; as a rule these contain some alkali, such as lime or caustic soda.

The preparation is brushed on to the paint required to be removed, and in the course of from ten minutes to half an hour the paint becomes so soft that it can readily be scraped off.