This specification covers a slow drying French process zinc oxide, raw linseed oil and alkyd primer suitable for use over hand-cleaned steel.
This primer is suitable for exposures in Environmental Zones 1A (interior, normally dry) and 1B (exterior, normally dry), and is intended for brush, roller or spray application over steel surfaces prepared in accordance with SSPC-SP 2, “Hand Tool Cleaning,” or better. (See Note 9.6.) Within the limitation stated in 2.1 it is suitable as a shop primer, field primer, maintenance primer, or intermediate coat and is to be applied in accordance with SSPC-PA 1, “Shop, Field, and Maintenance Painting of Steel.” If the primed part of the structure is to be exposed to the weather, it should be topcoated as soon as practical.
This specification contains requirements to ensure barrier inhibition composition. Consequently, performance is comparable to that customarily expected from paints containing lead and chromate pigments. It has good wetting ability, even for non-blast cleaned steel, about 36 hours drying time (generally it can be recoated after 24 hours, although the coating will not have achieved a through dry) and good resistance to weathering before field coating. The good wetting ability of this primer is the result of its high proportion of raw linseed oil. Type II has a lower percentage of volatile organic compounds (VOC) than Type I. The reduced VOC content of Type II was achieved by replacing some of the mineral spirits with high flash naphtha and by making other minor composition changes.
The Type I primer contains approximately 65% by volume of nonvolatile film forming solids (pigment and binder). The theoretical spreading rate for a 50 micrometer (2.0 mil) dry film thickness is 12.8 m2/L (520 ft2/U.S. gallon). Actual spreading rates can be significantly lower. On a calculated basis, the VOC is 270 g/L(2.3 lb/gal).
The Type II primer contains approximately 70% by volume of nonvolatile film forming solids (pigment and binder). The theoretical spreading rate for a 50 micrometer (2.0 mil) dry film thickness is 13.8 m2/L (560 ft2/U.S. gallon). Actual spreading rates can be significantly lower. On a calculated basis, the VOC content is 240 g/L (2.0 lbs/gal).
