Mechanical zinc coating allows mass production with a consequently excellent quality-price ratio, combined with the absence of hydrogen embrittlement and alteration of the hardness of the material.
Overcoatability, low environmental impact, film uniformity with film thickness from 5 to 110 µm, good corrosion resistance and the intrinsic compatibility with application of zinc and aluminium alloys or lubricating systems complete the many benefits offered by this type of treatment.
When coating performance is considered, hours to white or red rust are the normal criteria. However with high tensile fasteners, threaded or unthreaded, being free of hydrogen embrittlement is an equally important factor. For this reason components such as rivets and safety critical fasteners are zinc coated using a mechanically applied process rather than traditional electroplate. This process also offers advantages in bulk application against organic dip spin that even the smallest fastener can be treated without head / recess fill or parts sticking together.
This section specifies mechanically applied zinc coating. This coating shall be used on steel fasteners including bolts, screws, nuts and washers. Anchor bolts are coated as specified in Section 05910. Electroplated corrosion protection is not an acceptable substitute for mechanical zinc coating
Zinc Coating Thickness Coating thickness shall be Class 50 as specified in ASTM B695