CORROSION INFORMATION
All metal fasteners have the potential to corrode, including stainless steel screws. Corrosion can result from a number of different factors including environmental conditions, materials, construction design and other factors. No single guideline can address all corrosion possibilities.
Starborn offers four types of exterior fasteners:
- Epoxy coated carbon steel
- Epoxy coated grade 410 stainless steel
- Grade 305 stainless steel
- Grade 316 stainless steel
Choose the best fastener based on the material being fastened and the environmental conditions of the project location.
EXTERIOR COATINGS AND FINISHES
Epoxy Coated Steel
Starborn epoxy coated carbon steel screws have zinc plating and an epoxy based polymer resin overcoat. This coating is approved for use in pressure treated lumber. This coating is not recommended for the following applications:
- Surfaces where chrorine or de-icing salts are used.
- Projects within 1000 feet of salt water
- Redwood, cedar, tropical hardwoods or other woods with high tanin content
- Consistenly wet environments
Epoxy Coated Grade 410 Stainless Steel
Starborn epoxy coated grade 410 stainless steel has a higher carbon content then 305 and 316 stainless steel screws in order to increase hardness for penetrating through steel and aluminum joists. They are zinc plated and have an expoxy based polymer resin overcoat. This coating is approved for use in pressure treated lumber. This coating is not recommended for the following applications:
- Surfaces where chrorine or de-icing salts are used.
- Projects within 1000 feet of salt water
- Redwood, cedar, tropical hardwoods or other woods with high tanin content
- Consistenly wet environments
Grade 305 Stainless Steel
Starborn grade 305 stainless steel screws provide excellent corrosion protection in most situations. However, 305 stainless is not recommended for salt water and other highly chlorified environments.
Grade 316 Stainless Steel
Starborn 316 stainless steel screws are recommended in saltwater and other highly corrosive enviroments to minimize potential corrosion and/or discoloration of the fastener and surrounding materials.
| COMMONLY USED MATERIALS | COMMONLY USED FASTENERS |
|---|---|
| Pressure Treated Lumber | |
| Pressure treated lumber has presevative agents that help protect the wood from rot and insects and is commonly used for outdoor projects. | In normal environments, Starborn epoxy coated carbon steel screws provide excellent corrosion resistance. |
| Cedar, Redwood and Hardwoods | |
| Many tropical hardwoods, as well as cedar and redwood, contain large amounts of tannins and other chemical compounds that provide natural protection against deterioration. The natural chemicals can also cause staining and corrosion when they come into contact with zinc or carborn steel. | Stainless steel screws are always recommended. |
| Composite Decking & Fascia / PVC Decking and Trim | |
| Composite decking is basically a combination of wood pulp and recycled plastic. The ratio of wood to plastic varies depending on the brand. Compared to natural wood, the plastic in composite decking makes it more resistant to moisture and insects. Like composite, PVC is made from artificial materials. But instead of being a mix of wood and plastic, PVC decking and trim are 100% plastic. | Instructions Always follow installation instructions and fastener recommendations provided by decking manufacturer to determine whether stainless steel screws are required or if epoxy coated screws are sufficient. |
ENIVIRONMENTAL CONDITIONS TO CONSIDER
Environmental conditions must be considered separately from the material being fastened.
Common Example:
A treated lumber deck can normally be fastened with epoxy coated steel screws, but a treated lumber deck next to a swimming pool should be fastened with grade 316 stainless because it is a corrosive environment.
Below are some examples of environmental conditions to consider when choosing the right fastener:
- salt air or water
- swimming pools, docks, "splash-zones"
- surfaces where de-salting and harsh checmical cleaning products are used
- consistently wet enviromnents
- wood in direct contact with ground
Applications near water (especially salt water), swimming pools and other similar environments are subject to accelerated corrosion. The use of 316 stainless is recommended. However, staining or corrosion is still possible. Washing residues and salt deposits from the surface regularly will minimize potential corrosion and discoloration of surrounding materials.
STAINLESS STEEL IS RUST RESISTENT NOT RUST-PROOF
Stainless steel is armed with built-in corrosion resistance but it can corrode in certain conditions.
Tea staining of stainless steels is a phenomenon that can occur where water is in regular contact with the metal surface. This is a common occurrence along the coastal areas.
There are several precautions you can take to help prevent tea-staining occurring which include choosing the correct grade of stainless for your application and adequate cleaning or washing of the installed screw heads. It is important that residues and salt deposits are regularly washed from the surface. Regular maintenance is strongly advised.
