Permit me to disagree with you on this Jim.When we give a surface plating
of 6 to 7 microns;the threaded portion recieves 10 to 12 microns,blocking the penetration;that is why there are two grades of gages with G & H marking I have referred to in earlier post.
It really depends on the application. If there is a problem with plating buildup, it's likely to be limited to the first couple of threads. Plating has a tendency to buildup in areas of high current density, and this includes the peaks of threads. In practical terms, plating rarely penetrates far enough into a hole to make a difference, and when it does, it usually means that the parts have spent too much time in the bath. As far as "G" and "H" designations go, those are metric thread
classes, roughly analogous to designations such as "2B" in English threads. While they might be useful in preplate/post-plate situations, they are not intended for that purpose.
Here we are not talking about decorative coat,but about a corrosion resistance,since the sea journey in export consumes about 45 days!I being over protective,give lacquer quoting over the plating to combat corrosion.
The question was whether or not thread-chasing could breech a deposition intended for corrosion protection. I answered in the affirmative, but added that sometimes plating is used for purposes other than corrosion protection. By and large, zinc castings don't need corrosion protection. In cases where one is unsure about whether or not a protective deposition has been compromised, it's best to err on the side of caution, and/or do corrosion testing (salt spray, e.g.) to confirm the integrity of the deposit.
As for lacquer coating, if it's called for in the specifications that's fine, but it also presents an issue with buildup, perhaps more so than plating, because it's more likely to run into cavities.