Outdoor Use
Hot-dip galvanized finishes are commonly selected for exterior exposure and heavier corrosion protection.
ASTM Finishes and Coatings
A practical reference for common ASTM-covered finishes, coatings, and corrosion protection systems used on fasteners, steel hardware, anchors, threaded products, and construction materials.
Finish Reference
Showing 15 of 15 finish records.
| Finish | ASTM Standard | Appearance | Description | Common Use |
|---|---|---|---|---|
| Plain / Black | Product specification dependent | Bare steel, black oxide scale, or unfinished steel | No added protective coating. Common where corrosion resistance is not required or the item will be coated after fabrication. | Structural steel, threaded rod, bolts, fabricated parts |
| Hot-Dip Galvanized | ASTM A123, ASTM A153, ASTM F2329 | Dull gray to bright silver zinc coating | Steel is dipped in molten zinc, creating a thicker zinc coating for corrosion protection. A153 is commonly used for steel hardware; F2329 is specific to bolts, screws, washers, nuts, and special threaded fasteners. | Outdoor fasteners, anchors, rods, brackets, highway work, structural hardware |
| Mechanical Galvanized | ASTM B695 | Bright to matte silver zinc coating | Zinc is mechanically deposited onto steel. Often used where hydrogen embrittlement risk from electroplating is a concern. | High strength fasteners, washers, nuts, threaded products |
| Zinc Plated / Electro-Zinc | ASTM B633, ASTM F1941/F1941M | Bright silver, clear, yellow, or colored chromate/passivate | Electrodeposited zinc coating used for moderate corrosion protection. F1941/F1941M is commonly used for mechanical fasteners. | Indoor fasteners, screws, nuts, bolts, washers, light-duty hardware |
| Clear Zinc / Clear Chromate | ASTM B633, ASTM F1941/F1941M | Bright silver or bluish silver | Zinc electroplate with a clear supplementary conversion coating or passivate. Provides a cleaner appearance than yellow zinc. | General commercial fasteners and hardware |
| Yellow Zinc / Yellow Chromate | ASTM B633, ASTM F1941/F1941M | Yellow-gold iridescent zinc coating | Zinc electroplate with colored chromate or passivate. Traditionally used when increased corrosion protection or visual identification is desired. | Fasteners, brackets, hardware, general industrial parts |
| Phosphate and Oil | ASTM F1137/F1137M | Dark gray to black | Phosphate coating with oil for light corrosion resistance and lubricity. Not intended for severe outdoor corrosion exposure. | Bolts, nuts, screws, automotive and industrial fasteners |
| Zinc-Flake Coating | ASTM F3393 | Silver-gray or dark gray, depending on system | Non-electrolytic zinc-flake coating system used for corrosion protection, often selected to reduce hydrogen embrittlement risk. | High strength fasteners, coated bolts, screws, specialty hardware |
| Zinc / Aluminum Corrosion Protective Coating | ASTM F1136/F1136M | Silver-gray coating | Zinc/aluminum corrosion protective coating system for fasteners. Often used where enhanced corrosion resistance is required. | Metric and specialty fasteners |
| Cadmium or Zinc Chromate Organic Coating | ASTM F1135 | Varies by system | Older corrosion protective coating specification for fasteners. Cadmium use is limited due to environmental and regulatory concerns. | Legacy specifications, specialty fastener requirements |
| Aluminum Particle-Filled Coating | ASTM F1428 | Aluminum-gray | Aluminum-filled basecoat with organic or inorganic topcoat for corrosion protection on fasteners. | Specialty corrosion-resistant fasteners |
| Zinc Alloy Thermo-Diffusion Coating | ASTM A1059/A1059M | Matte gray zinc alloy coating | Zinc alloy coating formed through thermo-diffusion. Used on steel fasteners, hardware, and other products. | Fasteners, hardware, specialty steel products |
| Zinc-5% Aluminum Hot-Dip Coating | ASTM A1072/A1072M | Metallic zinc-aluminum finish | Hot-dip coating using a zinc-aluminum alloy for corrosion protection on iron and steel products. | Steel products requiring zinc-aluminum coating |
| Hot Tin / Hot Tin-Lead Dip | ASTM A1074 | Tin-bright metallic coating | Hot tin or tin-lead dip coating for ferrous and non-ferrous metals. Used in specific legacy or specialty applications. | Specialty metal parts |
| Galvanizing Repair | ASTM A780/A780M | Repair coating varies by repair method | Covers repair of damaged and uncoated areas of hot-dip galvanized coatings. | Touch-up and repair of galvanized steel after fabrication, handling, or installation |
Common Selection Notes
High Strength Fasteners
Check hydrogen embrittlement concerns before selecting electroplated finishes on high strength parts.
Threads and Fit
Thicker coatings can affect thread fit. Nuts and tapped parts may require oversizing or compatible coating practices.
Project Specs
Public works and DOT jobs may require a specific ASTM or AASHTO finish designation, not just a general finish name.
Need Help Choosing a Finish?
Send the requirement, environment, or project specification to Lord & Sons and we can help identify the correct finish or coating standard.