Why did part of our chain turn a yellowish color after
cleaning in vinegar?
This is 5/16" Acco galvanized chain purchased in 2018, installed on
boat in 2019.
We seldom
anchor where we use more than 40-50 meters of chain, often it's 20-30 m.
We cleaned the first 50 meters of chain soaking sections at a time for 2-3 days in a bucket with white vinegar. Most of the chain returned to a nice gray. But the area from about 12 meters to 28 meters, turned this bronze/yellow color that almost looks like iron oxide. However it doesn't clean off with vinegar. It is the area that had the most soft growth on it. We did use a microfiber towel to wipe this area of the chain to assist in
cleaning.
While this dirty area of chain was in the vinegar, it "boiled", some kind of chemical reaction that created foam.
What might of happened?