Cause of corrosion under sink plumbing connections?

[Patrick McCarthy]

Last year i noted that the chrome on the hinges to the doors on the bathroom vanity had a LOT of surface corrosion, so much so that i replaced them. My initial thought was that a bottle of Liquid Plumber was off-gassing and eating the metal, so i also put the liquid plumber out in the garage. However, i just noticed that the 1/4 stops for the water supply and the chrome rings surrounding them are REALLY corroded. A year ago when i replaced the discolored hinges i noticed some minor surface corrosion in the 1/4 stop valves, but not much. Today they are VERY concerning to me. The year old hinges are not showing any sign of corrosion, which tends to be self-fulfilling “proof” of my off-gassing theory, but do to the amount of corrosion on the other stuff i have serious doubts. Concerned i am missing something.

First question: am i on the right track re the off-gassing theory? We have toilet bowl cleaner under there as well - could that be an additional culprit?

Second question: the 1/4 stops are easy enough to replace but is there any inhibitor or spray i can put on the feed lines intergral to the (ungodly expensive German Dornbracht) faucet??

We remodeled in2010 and this is a double vanity i made back then. The other side shows no problems with the original hinges nor the “chrome” escutcheon plates, nor the “stainless steel” braided supply lines built into the faucet on that side.

Appreciate any insights you might share. Patrick

[Edward Weber]

More than likely you have a cleaning product that contains muriatic acid (or muriatic acid itself). This will cause corrosion on any metal in the enclosed area.
Remove your cleaning products, change out the hinges and steel braided lines.
Been there

[Jerry Bruette]

I would remove anything that has ammonia in it also. Years ago the flexible gas lines for appliances were made from copper or brass and now they're made from stainless. The copper/brass lines would be eaten by household cleaners that had acid or ammonia in them and would leak. That's probably what''s happening in your bathroom.

[Patrick McCarthy]

Gentlemen, thank you kindly. Patrick

[Bill Dufour]

Bleach, ammonia, etc.
Bill D