Just wondering about whether or not to passivate a new kettle. I assume this is normally done in commercial breweries. I understand this can be done on the homebrew scale with Star San. Any other thoughts or suggestions?
I used TSP per the instructions that came with my Stainless BrewBucket. The TSP is different these days, because it isn’t allowed in several jurisdictions - I think the new stuff doesn’t contain the phosphates, but I used it anyway.
Yes, it is always a good idea to passivate them when new or at least once per year (more frequently if you brew often). Give them a good cleaning with TSP or PBW then passivate them with Star San at the dilution rate of 1 oz. per gallon of water. I normally let the mixture sit in the kettle for about a half hour or so, wetting the sides frequently with a sponge if you don’t want to completely fill the kettle (which can get a bit expensive). This was recommended by SS Brewtech when I purchased my conical and it works very well.
Starsan does NOT passivate SS. Here is the link from our resource section…
Very true. Phosphoric acid doesn’t passivate stainless. You need nitric or citric acid to do the job correctly. Nitric acid as not fun to work with or dispose of but citric is, and it’s cheap too. Just use a 4% solution at 160 to 180f for a couple hours. Save your Starsan for sanitation.
Passivation is only needed on freshly machined or formed stainless steel. Passivation is NOT needed or required under normal brewery use. I’m confused as to why anyone would go through that effort more than once?
With regard to homebrewing scale, citric acid passivation is the most accessible method. Nitric acid is a very hazardous material.
I agree that nitric acid is the best way to passivate stainless, although it is very dangerous to use. However, I have used the StarSan dilution I previously mentioned to remove beer stone from my boil kettle and it shines up the stainless just fine. That is also what SS Brewtech recommends for their conicals.
Another product that does well on stainless is Bar Keepers Friend. It is oxalic acid and really shines up the outside of my boil kettle.
Martin’s idea of citric acid is also a good one.
The SSBrewbucket site indicates that the StarSan treatment can be used to paasivate at the rate of one ounce per gallon of water. The TSP is merely a cleaner - my recollection was close, but skewed. Glad to hear that passivation is generally unnecessary.
Oxygen does the passivation. Nitric acid cleans the surface and supplies Oxygen. Citric acid? Anyone know.
A clean surface of SS will passivate quickly when exposed to air.
That is how I remembered it many years ago when I bought my first stainless kettle - I am now at a point where my recollection gets foggy on where I heard things, so I went back to the SS BrewBucket info on their website and I suppose that they are being overly cautious with the suggested process. O2 exposure is enough for me (I am not fabricating these items, after all…).
Thanks, Jeff!
Passivation produces an oxide layer that prevents rust - that is what makes it “stainless” steel (the German name is rostfrei or rust-free). Newly manufactured items need passivation because the machining and welding can damage the oxide layer. The manufacturer should do this. In normal use, if you don’t see any rust then you don’t need to passivate.
How long does it take when just using air?
Thanks for the reply Goose! The main reason I asked this question is because my new kettle arrived with a jungle of scratch marks. This happened because the grain basket (BIAB system) was shipped inside the kettle and the feet on the basket were grating away at the bottom and sides of the kettle during shipping.
Cheers!
Sounds like they should “passify” you and send you new undamaged goods…
It is a rapid reaction. Minutes or less.
Citric Acid at the rate of 5.32 oz/gallon. Heat to 160-180F for 2 hrs. Rinse well with hot water, then let air dry for minimum of 24 hrs with 48 being best. Recently did it to my kettle and placed all miscellaneous SS items in there as well. Then reheated to 180F and drained into two kegs to passivate them as well. Not hard to do.
This is very interesting. I had never been aware that SS needed to be passivated at all.
I’m confused, if it takes minutes in air why do we need nitric acid?
Nitric acid does agressive cleaning and supplies Oxygen.
Here is John Palmer’s take
http://howtobrew.com/book/appendices/appendix-b/passivating-stainless-steel
I didn’t know it, but I deep clean every year to remove Beer stone with Bar Keepers Friend (oxalic acid), so Ihave repassivated in that process. It is nice to see the kettle shine like new!