ASTM F3019 – Coating Properties & Specification

ASTM F3019 specification establishes the performance and application standards for non-electrolytically applied zinc-flake composite coating systems. Designed specifically for fasteners, these coatings provide robust corrosion protection without the use of hazardous substances like hexavalent chromium, lead, cadmium, or mercury. This specification is applicable to both inch and metric fasteners, including threaded bolts with minimum nominal diameters of 0.250 in. or [6.00 mm], as well as non-threaded hardware such as washers and pins. To successfully implement this standard, engineers and specifiers must categorize their requirements into one of four Grades, which define the presence of topcoats and integral lubricants. These systems are typically applied using conventional dip-spin, dip-drain, or spray methods and are cured at temperatures not exceeding 482°F [250°C]

Coating Properties

The performance of an ASTM F3019 coating is defined by its ability to resist corrosion and maintain specific friction properties. The classification system is divided into four grades: Grade 1 (basecoat only), Grade 2 (basecoat with integral lubricant), Grade 3 (basecoat with organic topcoat), and Grade 4 (basecoat with inorganic topcoat). Critical technical requirements include:

  • Adhesion: Systems must meet a 4A rating per ASTM D3359, showing only trace peeling after an X-cut tape test.
  • Corrosion Resistance: Performance is directly linked to coating thickness; for example, a [10 µm] coating must withstand at least 960 hours of neutral salt spray without red corrosion on significant surfaces.
  • Friction Control: Total coefficient of friction (μtot) is strictly controlled for Grades 2, 3, and 4 to ensure consistent torque-tension relationships during assembly.
  • Hydrogen Embrittlement: Because these coatings are non-electrolytically applied, they do not generate hydrogen during the coating process itself, though acid-based pre-treatments should be avoided to prevent adsorption.
The table below represents the Coating System Classification for selecting grades based on appearance and friction requirements, while the subsequent table is the Neutral Salt Spray Test Requirements, which provides the mandatory minimum coating thickness required to achieve specific levels of corrosion resistance measured in hours

Coating System Classification
Grade Coating System (Basecoat / Topcoat) Color Code Finished Appearance Friction Code Average Total Coefficient of Friction (μtot)A
1 Zinc-Flake / None ... Silver / Grey ... ...
2 Zinc-Flake w/Integral Lubricant / None ... Silver / Grey ... 0.14 ± 0.03
B Black L2 0.14 ± 0.03
... ... L3 0.17 ± 0.03
... Dark Blue ... 0.17 ± 0.03
... Green ... 0.17 ± 0.03
3 Zinc-Flake / Organic Topcoat DGKAS Light Blue ... 0.17 ± 0.03
R Red ... 0.17 ± 0.03
S Silver L2 0.14 ± 0.03
L3 0.17 ± 0.03
Y Yellow ... 0.17 ± 0.03
L1 0.11 ± 0.02
4 Zinc-Flake / Inorganic Topcoat ... Silver / Grey L2 0.14 ± 0.03
... ... L3 0.17 ± 0.03
Neutral Salt Spray Requirements
Test Duration to First Appearance of Red Corrosion (Hours) Minimum Average Coating Thickness of the Applied Coating System
Inch [Metric]
240 0.157 mils [4 µm]
480 0.197 mils [5 µm]
600 0.236 mils [6 µm]
720 0.315 mils [8 µm]
960 0.394 mils [10 µm]