[Dana Acker]

In our winery, we had stainless steel tanks, the smallest was about 70 gallons, the largest was 4000 gallons, with a total gallonage of about 28,000 gallons of fermentation/storage space.

When we fermented red grapes in tank, as red wine gets its color from skin contact from the whole grape in the mix, we encountered stains.

When the fermentation completed, and we pressed the wine off the solids, returning it to tank, where we chilled it to 33 degrees to keep it preserved until it was transferred to barrel. When the tank was emptied, the cold from the chilling jackets had caused some of the tartaric acid to have both precipitated out of the wine and had adhered to the walls of the tank. So there was this red film that felt like shark skin or sand paper. The only way to remove it was either by blasting it with a pressure washer with the water temp up to almost boiling, or dangerous caustics.

Some times even after the granulated tartrates were removed, there still remained a red stain (not textured—shark skin removed) that only could be removed by over 170 proof ethanol. Remember these were high quality stainless steel tanks—non-magnetic due to the chromium content.

So what might occur to carbon steel if plunged into a sponge soaked with red wine? Cheaper red wines would probably be better because better wines have had the tartrates stabilized. A $5.00 bottle of wine might work better than a $20.00+++ bottle.

Just a thought....