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What are the recommended ways to (a) clean/sanitize stainless steel and (b) if necessarry passivize the stainless steel after the treatment?

While there is a question asking about "Cleaning stainless steel", this question, despite its title, is rather "how to revocer/repair a damaged stainless steel".

What I would like to know is:

  • what chemicals to use for cleaning (detergents and sanitizers)
  • what chemicals to avoid (to not deteriorate the stainless steal)
  • what tools to use / to avoid (i.e. are "abrasive cleaning pads" a no-go, as they scar the surface)?
  • when/is re-passivation of the stainless steel necessary?

To give some background to the question here some background:

My brew-setup (pots, fermenters, valves) consists of stainless steel alloys which I want to clean, i.e. remove also not eye-visible biological agents (in order to avoid contamination. Even though my setup is stainless steel alloys of the 300 series, it might be necessary to follow up any cleaning agent, with a passivating, re-passivation step, as to not risk the anti-corrosive attribute of the stainless steel.

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Last thing first. There is no need to worry about passivating the stainless steel. Once cleaned it will re-passivate when in contact with air and the residual moisture from cleaning. Its almost instantaneous.

Non-iron containing scrub pads are required for mechanical cleaning. Green scrubbies often found with sponges are fine. For less abrasive cleaning a sponge should work most of the time.

Cleaning agents are many. Check the labels for safety with stainless. That said stainless is pretty resistant to normal contact time cleaning. In the homebrewery, hot soaks in PBW or oxiclean work fine and usually require minimal mechanical cleaning after wards. For stubborn beer stone of the like Bar Keepers friend works great as a spot cleaner. I have also used CLR in a pinch as well. Just be sure to use it at the recommended dilution. Probrewers will use different regimens of acid and caustic depending on what the soil being removed is. I point this out only to emphasize the durability of stainless steel.

All that being said, really hard cleaning of a stainless fermentor is all I'd worry about. PBW and a good wipe out of the kettle is more than enough. Microbially speaking the kettle is getting sanitized during the boiling of the hot wort.

  • Appreciate the information contained, which I think would still benefit if PBW (Powdered Brewery Washer) and CLR (Calcium Lime & Rust Remover) even though clear to many users, would be spelled out once still. As you rightly pointed out my question about sanitation was more targeted towards the fermeters not the hot-hence-sterilized brewing pots. – humanityANDpeace Feb 23 '17 at 12:08
  • Your mention about caustic (i.e. the regimes of probrewers) meant to say caustic soda NaOH, right? Does caustic soda cleaning would required repassivation? The way you put it repassivation is almost never needed right, yet I have read about it existing. When is repassivation needed (ever) if not as a part of cleaning? – humanityANDpeace Feb 23 '17 at 12:10
  • Lets put it this way, you CANNOT prevent the passivation of stainless! If you mar the chromium oxide layer through normal cleaning practices it passivates on its own. I suppose the only way for it not to happen would be an a vacuum or a space devoid of oxygen. Point being, unless you completely remove all the chromium from the alloy (not going to happen) the pot will passivate completely on its own under normal cleaning practices. The link you put about the dude who sandblasted his pot is not a normal cleaning practice FWIW. – brewchez Feb 23 '17 at 18:31
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    This should be the accepted answer. – brendo234 Mar 2 '17 at 20:48
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Passivation is a surface layer of oxide that prevents rust. If you don't have rust you don't need to worry about passivation. I bought a cheap kettle that began to rust around the welds after the first use. I used Barkeeper's Friend to repassivate it and now it is fine. I use a sponge with a soft scrubber and clean it before anything dries on, so simple wiping is good enough. If you have a fermenter with a dried krausen ring, soak it with one of the cleaners mentioned above (dissolved in hot water) until the crud comes off with little effort so you don't have to worry about doing damage by hard scrubbing.

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