Materials and Coatings Available for Fasteners
Simpson Strong-Tie Company Inc. welcomes the opportunity to provide assistance in fastener selection. Please call (800) 999-5099 in the event that technical support is needed.
Corrosion Resistance Classifications
Low Level of Corrosion Resistance
Blue-Bright Zinc
Electroplated zinc applied in accordance with ASTM F1941. In the ASTM B117 salt spray test, blue-bright zinc provides at least 36 hours of corrosion protection before the first appearance of red rust.
Clear Zinc
Electroplated clear zinc is applied in accordance with ASTM F1941. In the ASTM B117 salt spray test, clear zinc provides 24 hours of corrosion protection before the first appearance of red rust depending on coating thickness.
Electrocoating (E-Coat)
Electrocoating uses an electrical current to deposit the coating material onto the fastener.After application, the coating is oven cured. Electrocoat is intended for dry service, low-corrosion applications and is suitable for use with FRT in medium-corrosion, dry-service applications.
Gray Phosphate
Gray phosphate provides a minimum level of corrosion resistance and is intended for dry, low-corrosion applications.
Black Phosphate
Black phosphate provides a minimum level of corrosion resistance and is intended for dry, low-corrosion applications.
Yellow Zinc
Electroplated zinc applied in accordance with ASTM F1941. In the ASTM B117 salt spray test, yellow zinc provides at least 72 hours of corrosion protection before the first appearance of red rust.
Class 1 Zinc Electroplate
Electroplated zinc applied in accordance with ASTM A641, Class 1. This is an electroplated zinc coating that provides a low level of corrosion resistance. The Class 1 coating has no specified red rust performance criteria in the B117 salt spray test.
Type 410 Stainless Steel
Type 410 stainless steel is a low-carbon martensitic grade of stainless steel that can be hardened and is inherently magnetic. This material provides corrosion resistance in mild atmospheres and many mild chemical environments.
Coated Zinc
This coating system consists of an electroplated zinc base layer with an E-Coat top coat. It provides corrosion resistance that is adequate for low corrosion environments. In ASTM B117 salt spray testing at 500 hours of exposure, fasteners with this coating have an average red rust of less than 5%.
Medium Level of Corrosion Resistance
Quik Guard® Coating
Quik Guard coatings are proprietary coating systems that consist of an electroplated zinc base layer and organic top coats. The corrosion resistance is equivalent to hot-dip galvanization (ASTM A153, Class D) in some exposures and in most non-marine environments, and described by ICC-ES, AC257 Exposures 1 and 3.
Double-Barrier Coating
The Simpson Strong-Tie double-barrier coating is a proprietary coating that provides a level of corrosion resistance that is equivalent to hot-dip galvanization (ASTM A153, Class D) in most non-marine environments and as described by ICC-ES, AC257 Exposures 1 and 3.
Hot-Dip Galvanized, ASTM A153, Class D
The Class D hot-dip galvanization is a coating that meets the requirements of ASTM A153, Class D, which is a minimum average of 1.0 oz/ft2 [305 g/m2] of zinc applied by a hot-dip process. Hot‑dip galvanized fasteners are compliant with the 2018, 2021 and 2024 IBC and IRC.
Mechanically Galvanized, ASTM B695, Class 55
This is a mechanically applied zinc coating that meets the requirements of ASTM B695, Class 55, which is a minimum average thickness of 55 microns with a supplementary overcoat. Screws with a Class 55 coating meet the requirements for use in preservative‑treated and fire‑retardant‑treated wood as stated in the 2018, 2021 and 2024 IBC and IRC.
N2000® Mechanically Galvanized
This is a mechanically applied proprietary zinc coating with a supplementary overcoat. In the ASTM B117 salt spray test at 1000 hours of exposure, fasteners with the N2000 coating exhibit average red rust less than 15%.
C-3 Mechanically Galvanized
A mechanically applied coating that is zinc with a minimum of 20% tin in accordance with Australian Standard AS3566.2. In the ASTM B117 salt spray test at 1,000 hours of exposure, fasteners with the C3 coating exhibit average red rust of less than 2%.
High Level of Corrosion Resistance
Types 304 and 305 Stainless Steel
Types 304 and 305 stainless steels are nickel-chromium austenitic grades of stainless steel. Types 304 and 305 stainless steels are not hardened by heat treatment and are inherently nonmagnetic.
They provide very good corrosion resistance and are suitable for use in many corrosive environments. Fasteners made from Types 304 and 305 stainless steels are compliant with the 2018, 2021 and 2024 IBC and IRC.
Severe Level of Corrosion Resistance
Type 316 Stainless Steel
Type 316 stainless steel is a nickel-chromium austenitic grade of stainless steel with 2-3% Molybdenum. Type 316 stainless steel is not hardened by heat treatment and is inherently nonmagnetic. It provides a level of corrosion protection suitable for severe environments, especially environments with chlorides. Type 316 stainless‑steel fasteners are compliant with the 2018, 2021 and 2024 IBC and IRC.
Hot-Dip Galvanized, ASTM A153, Class C
Class C hot-dip galvanization is a coating that meets the requirements of ASTM A153, Class C, which is a minimum average of 1.25 oz/ft2 [381 g/m2] of zinc applied by a hot-dip process. Hot‑dip galvanized fasteners are compliant with the 2018, 2021 and 2024 IBC and IRC.
* Passivation of Stainless-Steel Fasteners
Stainless steels are designed to naturally self-passivate by forming a chromium oxide layer. Corrosion resistance of some stainless-steel fasteners is enhanced by a post-fabrication passivation process. The passivation process uses an acid bath to strip free iron from the surface and an oxidizer to force conversion of the surface chromium to the oxide form.
General Note About Salt Spray Testing
Salt spray testing in accordance with ASTM B117 is not intended to represent real-world corrosion performance of fastener coatings. It should only be used for comparative evaluation between like products. Many variables may affect the outcome of the salt spray test such as base material, fastener features, coating and the material where it is installed.