Stainless steel is sensitive to any acid. Even common such as orange juice are acidic enough to make permanent etches on some stainless steel.
Fumes from some strong acids can make a slight etch.
The safest course is to protect any metal surface, especially stainless steel.
When accidents do occur, it is important to remove and neutralize the spill or splash as quickly as possible. Most alkaline cleaners will be fine for neutralizing the acid.
Factors That Determine The Severity of an Etching:
1) What is the pH of the acid?
2) What is the concentration level of the acid?
3) How long did it dwell on the surface?
4) What is the grade or quality of the stainless steel? (There are dozens of grades available. Some etch or stain pretty easily.)
How to Remove Acid Etching
Removing an acid etching is usually accomplished through buffing.
How much buffing and with what abrasive compound depends upon the severity of the etching. For light marks try a product called “Bar Keeper’s Friend.” This is sold at restaurant supply stores and its purpose is for cleaning stainless steel in restaurants.
Follow label directions. Make sure to buff and polish to blend in the affected area. Work from the bottom up. A microfiber cloth works well but you can also use a cotton bar towel.
More severe damage will require stronger abrasives. Try various grades of automotive rubbing compound. You can also try 0000 or 000 steel wool.
Small areas can be done by hand.
Work with the grain of the stainless steel. Working across the grain can leave new scratches.
With some very fine abrasives, you may use a variable speed drill with a buffing pad attachment.
Unfortunately, replacement of the stainless is frequently required. Usually, only a decorative panel or one piece of the damaged product requires replacement, not the entire appliance.
Remember to appropriately mask off stainless steel surfaces when cleaning with an acid in close proximity.