This specification covers one group of highly pigmented zinc-rich coatings that are uniquely defined by their capability of galvanically protecting steel exposed at discontinuities such as narrow scratches and holidays. While the major pigment component in this coating is zinc dust, the vehicle may be inorganic (Type I) or organic (Type II).
This specification does not cover all types of zinc-rich coatings. For example, it is not a straight performance specification, nor does it pertain to extended zinc-rich coatings, nor to weldable pre-fabrication zinc-rich primers, which are applied at low thicknesses (approximately one mil [25 micrometers] or less). Further information regarding these and other zinc-rich coatings can be found in SSPCPS Guide 12.00, "Guide to Zinc-Rich Painting Systems," and other SSPC specifications.
This specification defines the minimum compositional and laboratory performance requirements for identifying a group of zinc-rich paints. It is to be used in conjunction with SSPC-PS Guide 12.00, "Guide to Zinc-Rich Painting Systems"; and with other SSPC specifications covering surface preparation, applications, thickness, inspection, and safety.
This primer, when applied over properly prepared steel surfaces, is suitable for use on parts or structures exposed in Environmental Zones 1A (interior, normally dry), 1B (exterior, normally dry), 2A (frequently wet by fresh water), and 2C (fresh water immersion). They may be used in Environmental Zones 2B (frequently wet by salt water), 2D (salt water immersion), 3A (chemical, acidic), and 3C (chemical, alkaline) with proper topcoating.
This primer is intended for application by spray and is to be applied in accordance with SSPC-PA 1, "Shop, Field, and Maintenance Painting of Steel."
The zinc-rich coatings described in this specification consist of zinc dust, an organic or inorganic vehicle, and selected additives as required.
PIGMENTATION:
1) The major pigment component in these coatings is zinc dust of the type described in ASTM D 520, "Zinc Dust (Metallic Zinc Powder)."
2) Other pigment components may include curing aids, tinting colors, suspension and pot life control agents, but should constitute only a minor part of the total pigment portion so as not to detract from the ability of these coatings to protect galvanically.
VEHICLE TYPES:
Type l-A, inorganic post-curing vehicles—water soluble, include alkali metal silicates, phosphates, and modifications thereof which must be subsequently cured by application of heat or a solution of a curing compound.
Type l-B, inorganic self-curing vehicles—water reducible, include water soluble alkali metal silicates, quarternary ammonium silicates, phosphates, and modifications thereof. These coatings cure by crystallization after evaporation of water from the coating.
Type l-C, inorganic self-curing vehicles—solvent reducible, include titanates, organic silicates, and polymeric modifications of these silicates. These systems are dependent upon moisture in the atmosphere to complete hydrolysis, forming the polysilicate.
Type II, organic vehicles—include phenoxies, catalyzed epoxies, urethanes, chlorinated rubbers, styrenes, silicones, vinyls, and other suitable resinous binders. The organic vehicles covered by this specification may be chemically cured or may dry by solvent evaporation. Under certain conditions heat may be used to facilitate or accelerate hardening.
