Threaded fasteners are typically specified in English units (inch series) or Metric standards. US - inch standards are usually defied by SAE (Society of Automotive Engineers) standards or IFI (Industrial Fasteners Institute) standards. Metric fasteners are typically specified by ISO (International Organization for Standardization) , DIN (Deutsches Institut für Normung), or JIS (Japanese Industrial Standard) standards. These specifications define material, physical properties, and form in a variety of standards.

Items to consider when specifying a fastener: Specify material, physical property (strength), fit class, manufacturing method (e.g. rolled threads), physical form (shape), size, and finishing.

Corrosion protection levels of fasteners are frequently in dispute in that the achievable levels and nomenclature are often misunderstood, and misapplied.

Plating is very important for steel fasteners to prolong the life expectancy in corrosive environments. Steel fasteners are commonly zinc plated, or cadmium plated, with zinc plating the most common in the US due to environmental controls. Zinc plating is used on steel fasteners to provide a sacrificial surface for corrosion to occur, thus saving the base metal. The zinc/iron combination produces an anode-cathode relationship with the zinc being anodic (active) causing the iron to become cathodic (inactive). Once the zinc has been "used up", it can no longer protect the base metal and red corrosion occurs. At this point, the fastener has failed with respect to corrosion resistance.

The key to extending the corrosion resistance is to adequately specify all aspects of the finish treatment. The corrosion resistance of zinc plating is measured in hours of salt spray resistance (ASTM B117), and is a function of plating thickness, and conversion coatings. The thickness of the plating is directly proportional to the length of time a fastener will remain protected in a given environment. This is further defined in ASTM B633, Appendix X1.1

This resistance can be effectively increased significantly by selecting the appropriate post plating finish treatments. The most common types of zinc plating finish are; no finish - plain zinc (shiny silver to dull gray), clear chromate (shiny silver with a very faint blue tint), or yellow chromate (shiny gold with a very faint green or brown tint). Plain zinc provides only the resistance of the zinc plating, commonly 48-96 hours of salt spray resistance. Clear chromate adds 8-24 hours of salt spray resistance (commonly applied for staining resistance due to handling), while yellow chromate adds 72-112 hours of salt spray resistance. Chromate conversions do not add any significant plating thickness to the fastener, so they may be applied over the maximum zinc plating thickness.

Fasteners or fastener components with a hardness greater than or equal to 320 HV (32 HRC) are susceptible to hydrogen embrittlement when these parts are pickled and/or electroplated. This may cause these fasteners to fail at relatively low loads even if stress relief annealing (baking) is performed after plating. Examples of hardened fasteners are steel bolts - US Grade 8 (Metric grade 10.9), hardened steel washers, or spring washers. These types of fasteners should be mechanically zinc plated, with a yellow chromate conversion (Zinc Yellow Dichromate finish) per ASTM B 695 or with Dachromate 320. An exception to this requirement is that split ring type lock washers, of a size equal to or less than 3/8" (M10), may be effectively electroplated and baked according to the specifications in ISO 4042, Annex A.