Post
by Eric » Mon Mar 13, 2023 2:35 pm
From what you describe, it doesn't sound like limescale. Citric, or any other, acid would be seen in action instantly if it was. Has the vessel been used for brewing in the past? If it has, it could likely be beerstone, calcium oxalate, deposited during fermentation.
It's a sod to remove from stainless steel if allowed to dry, vastly easier if tackled immediately upon transfer. Also some types of stainless are worse than others, particularly some cheaper grades.
I could get it off plastic with a mix of EDTA and caustic soda, but that doesn't seem to work as well on stainless.
Without patience, life becomes difficult and the sooner it's finished, the better.