Nobody curls up by the fire with ASTM B633. They should. It is the cleanest communication you will get all year, because it tells you exactly what it wants and it never plays games.
B633 is the standard for zinc plating on steel, and it speaks in two parts. First, a service condition class that sets the zinc thickness for the world the part has to survive:
- SC 1, mild: about 5 microns of zinc, for the easy life.
- SC 2, moderate: about 8 microns, for a little weather.
- SC 3, severe: about 12 microns, for parts that get bullied.
- SC 4, very severe: about 25 microns, for parts that live outside and resent it.
Second, a type that names the chromate on top, running from plain zinc with no chromate through the colored and clear passivates, including the trivalent RoHS versions. Your drawing names a class and a type, and that little pair tells us everything we need to plate it right.
This is the whole beauty of a spec. There is no guessing and there are no vibes. You hand us B633 with a class and a type, we hit it, and we document the work so it drops straight into your quality system. We plate to B633 every single day, so the romance never wears off.
Have a print with a B633 call-out you are not totally sure about? Send it over. We will read it with you, and unlike most relationships, this one comes with documentation.