[ANorwood]

So I was pickling some hot rolled steel to remove the scale and I usually do. However I was doing it this time near some finished parts made from hot roll. I guess the fumes from the hydrochloric acid got to the finished parts and left a nice ugly yellow patina on them all in blotches. I took some scotch bright to the parts and they were able to get shined up, but still have a stain on them. Are there any chemical applications anyone know of to remove the stain?

[harryn]

I am not completely sure how to fix that problem, but perhaps first some steps are needed to keep it from getting worse.

The acid fumes are a mix of HCl and water, one of the most insideous corrosives that people deal with. The HCl is able to absorb / desorb into almost anything (example, the wood box behind the parts) and will pass through most plastics and building materials.

It is likely that not all of the fumes have been removed from the area yet unless you have done something with an alkaline solution. Baking soda can help with neutralizing it, but don't use anything ammonia based, or it can make the problem worse.

(makes a solid that re- fumes like HCl)

I will give some more thought to the affected parts, but it is not a "stain", it is corroded, and it will need to have the affected material removed.