This specification covers a very slow drying black, one-coat, raw linseed oil maintenance primer for steel. It has fair rust inhibitive characteristics, good wetting ability, a drying time of about one week, and good resistance to weathering without field coating.
This primer is suitable for exposures in Environmental Zones 1A (interior, normally dry) and 1B (exterior, normally dry), and is intended for brush and spray application over steel surfaces prepared in accordance with SSPCSP 2, "Hand Tool Cleaning." The performance will be improved by a better degree of surface preparation. It is suitable as a maintenance primer and is to be applied in accordance with SSPC-PA 1, "Shop, Field, and Maintenance Painting of Steel." It is not ever used as a shopcoat for steel because of its very long drying time. It is unsuitable for use where the uncured, slippery paint film would be dangerous to workmen when walking or climbing on painted surfaces.
This specification is based on Patent No. 2,858,285 which was assigned to the DuPont Company in 1959.
The good wetting ability of this primer is the result of its high proportion of raw linseed oil. Details of the composition are given in Table 1.
This primer contains approximately 87% by volume of nonvolatile film-forming solids (pigment and binder). The theoretical spreading rate for a 4.0 mil (102 micrometers) dry film thickness is 350 square feet/U.S. gallon (8.6 square meters/liter). Actual spreading rates can be significantly lower.
