The Benefits of Stainless Steel in Brewing Equipment
Stainless steel doesn’t corrode, flavour the beer or mind strong cleaners. How it compares with copper, aluminium and plastic, 304 vs 316, and how to look after it.
In this post
The short answer: stainless steel is the standard for brewing gear because it doesn’t corrode or flavour the beer, it’s tough, and it stands up to hot caustic cleaners and acid sanitizers. It is not a good conductor of heat, which is why electric kettles heat the wort directly with an element and many chillers are copper. Most homebrew and craft gear, ours included, is 304 stainless; 316 adds molybdenum for better resistance to chlorides.
| Material | Heat conduction | Corrosion and cleaning | Typical use |
|---|---|---|---|
| 304 stainless | Low | Excellent; takes alkaline cleaners and acid sanitizers | Kettles, fermenters, fittings |
| 316 stainless | Low | Better against chlorides and salt | Premium fittings, harsh environments |
| Copper | About 25× stainless | Reacts with acidic wort and cleaners; darkens | Wort chillers |
| Aluminium | About 13× stainless | Softer; caustic cleaners attack it | Budget kettles |
| Plastic | Very low | Scratches can harbour bacteria | Buckets, carboys |
Why brewing gear is stainless
Stainless steel is steel with at least 10.5% chromium. The chromium forms a thin, invisible oxide layer on the surface that stops rust, and if you scratch it, the layer rebuilds itself in air. That gives brewers four things:
- No flavour. Clean stainless doesn’t react with wort or beer, even acidic beers.
- Strong cleaners. It takes hot caustic cleaners and acid sanitizers, batch after batch.
- Smooth, welded surfaces. Polished interiors and sanitary tri-clamp fittings leave few places for soil to hide, so gear cleans in place.
- Strength. Stainless vessels can hold pressure, which is what lets a Unitank ferment under pressure and push beer to a keg with CO₂.
304 vs 316
| 304 | 316 | |
|---|---|---|
| Alloy | About 18% chromium, 8% nickel (“18/8”) | Similar, plus about 2% molybdenum |
| Chlorides and salt | Can pit if chlorine or salt sits on it | Much more resistant |
| Used for | Most kettles, fermenters and fittings | Marine, coastal and chemical plants; some premium fittings |
| For homebrewing | Plenty, if you keep bleach off it | Not needed |
The weak spot: heat
Stainless conducts heat about 25 times less well than copper. It matters less than it sounds, because good gear works around it:
- Electric kettles put the element inside the wort, so the heat never has to pass through the steel.
- Kettles for burners and induction use a tri-clad base: a conductive aluminium layer sandwiched in stainless to spread the heat and prevent scorching.
- Chillers use copper, or a long stainless coil. In a chiller, the thin tube wall isn’t the bottleneck, so extra length makes up the difference. See copper vs stainless chillers.
How to clean and care for stainless
- Rinse soon after use, before anything dries on.
- Clean with a hot alkaline brewery cleaner such as PBW, with a soft cloth or non-scratch pad.
- Rinse well, then sanitize cold-side gear with an acid sanitizer. Acid also keeps beer stone from building up.
- Let it air-dry. The protective layer needs oxygen to rebuild.
Avoid: bleach and chlorinated cleaners (they cause pitting), steel wool and carbon-steel brushes (they leave iron behind that rusts), and letting salty or chlorinated water dry on the surface.
Troubleshooting
| What you see | Cause | Fix |
|---|---|---|
| Orange rust spots | Iron from steel wool, tools or water, not the stainless itself | Scrub with an oxalic-acid cleanser, rinse, let it air-dry |
| Chalky white or brown film | Beer stone (calcium oxalate) or water scale | An acid brewery cleaner; alkaline cleaners alone won’t shift it |
| Rainbow or straw colour | Heat tint near welds or a burner | Cosmetic; an oxalic-acid cleanser lightens it |
| Tiny pits | Chlorine or salt left on the surface | Stop using bleach; rinse and dry after cleaning |
Frequently asked questions
Is stainless steel safe for beer?
Yes. Food-grade 304 and 316 are what breweries, dairies and kitchens use, and clean stainless adds nothing to the beer.
Does stainless steel rust?
Not on its own, in normal brewing use. Rust spots almost always come from iron left on the surface or from chlorine damage.
Can I tell 304 from 316 with a magnet?
No. Both are mostly non-magnetic, and welds or bent areas of either can be slightly magnetic. Go by the maker’s spec.
Is a stainless fermenter worth it over plastic?
If you want to ferment under pressure, cool through a jacket, or stop replacing scratched buckets, yes. Plastic works fine to start with. See stainless Unitank pros and cons.
Related guides
Copper vs stainless chillers, cleaning and sanitizing a fermenter, how to choose a brewing kettle and stainless Unitank pros and cons. See our stainless Unibräu DrainPro and Unitank.