Finish
The coating or treatment applied to the bolt's surface for protection against corrosion and wear.
Black Oxide
An extremely thin attractive finish with minimal corrosion resistance. This coating reduces galling, improves lubrication of mating parts and reduces glare. This finish looks great when trying to achieve a stylish or "high-tech" look on exposed fastener heads.
Black Zinc
Provides mild corrosion resistance with black coloring. It is thicker than a Black Oxide finish, so on tight fitting parts be wary of this finish. Its irridescent flashy accents are why it is primarily used as a decorative finish.
Cadmium
Offers good corrosion resistance in a very thin layer. Meaning that part with low tolerances still fit together with this plating. Used mainly in the aerospace and avaiation industries. Easily paintable.
Chrome
This finish improves appearance and provides mild corrosion resistance. It can also increase surface hardness, which improve abrasion resistance, reduces friction, and prevents seizing. This finish is shiny and aestheticly pleasing.
EcoGuard®
This finish provides some of the highest corrosion resistance. This finish has been tested at a minimum of 1000 hours in the salt spray test for corrosion, eliminates hydrogen embrittlement, and is free of toxic metals. This a great corrosion-resistant, environmentally-friendly finish.
Plain
This bare metal surface has no finish for improving appearance or corrosion resistance, which is very low if the material is steel. Often the surface has been oiled, which improves lubricity. Plain finish fasteners can be used indoors or in outdoor environments where corrosion protection is not an issue.
Yellow Zinc
This irridescent electroplated zinc finish, also known as Yelllow Zinc Chromate or Dichromate, provides very good corrosion resistance and protection against rust. This finish should not be used in marine or high salt spray environments.
Zinc
This finish, also know as zinc plating, zinc chromate or dichromate provides good corrosion resistance and is the standard for many hardware fasteners. It is an electroplated zinc layer covered with a chromate post-treatment. The zinc protects the steel from corrosion and the chromate layer protects the zinc from degrading. It is a popular finish because of its protection, cheapness, and ease of coating. Slightly less corrosion resistant than yellow zinc, it is a versatile finish that is best used indoors. This finish should not be used in marine or high salt spray environments.
