Dear Mr. Wizard,
My current stainless-steel brew pot is only five gallons and has developed a crack in the rim. I need to replace it with something larger that will not break my bank account and send my wife into a frenzy. I know that stainless is highly recommended for use as a brew kettle and I understand why, but are there any cheaper alternatives? I have read articles, including one by you, that say that using aluminum can be OK. Is this true? Also, what about the ceramic canning kettles that are readily available?
Lock Haven, PA
Mr. Wizard replies:
A pot really only needs to satisfy a few simple requirements to become a qualified brew pot. For starters, it ought not to leak — a leaky kettle is a problem. A good candidate for the job should also be large enough to hold a whole batch of wort. In your case, that means 5.5 to 6 gallons of wort before boiling, plus about 20 percent extra space to prevent boilovers. Using this formula, you need about a seven-gallon kettle. If you can, it is much better to boil the whole volume of wort instead of doing a concentrated wort boil. A concentrated boil affects hop utilization, aroma changes to wort during boiling and color development much differently than doing a full wort-volume boil. The kettle should also be constructed from a material that can adequately conduct heat from the heat source to the wort. This is one property of stainless steel that is less than stellar. The final qualifier for the kettle is that it should not harm the wort by leaching compounds into it.
Stainless steel is certainly the most common material for kettle construction nowadays. Stainless steel is inert, is easily formed and welded and can be heated either by direct flame or with the use of steam jackets and coils. Steam is used by commercial brewers because it does not result in scorching. Unfortunately, stainless steel kettles are pretty spendy. A seven-gallon stainless steel pot can easily cost more than $150.
Ceramic canning vessels, also known as crab or lobster pots, certainly meet the basic requirements for a kettle. Canning vessels are usually made of tin with a thin enamel coating. These vessels are inert, have a high heat conductivity and they are less expensive than stainless pots. One drawback to ceramic pots is that you cannot weld a valve to them because the ceramic coating chips off. In addition, if they get chipped or cracked, the metal under the ceramic is not inert. If you are careful with how you handle these pots and don’t mind not having an outlet valve, then this is one viable option. A minor drawback is that the handles of canning pots are not very strong and you should not attempt to lift a pot full of near-boiling wort. This is dangerous regardless of the handles and really ought to be avoided.
Aluminum pots are readily available in all sorts of sizes, are really inexpensive and have a terrific thermal conductivity. An outlet valve can be welded to an aluminum pot, but you will probably have a difficult time finding anyone who can weld a stainless steel ferrule to an aluminum pot because aluminum welding is a fairly specialized technique. The other issue with aluminum is that it is not inert. The main problem with this feature, especially in commercial applications, is that aluminum is readily dissolved by sodium hydroxide (commonly known as caustic) and caustic-based cleaners are the workhorse cleaners of the food and beverage industries. Any cleaner containing sodium hydroxide will have it on the label because sodium hydroxide is pretty nasty. Draino and Easy-Off both contain sodium hydroxide. The best advice is to read the label.
Aluminum has also been associated with Alzheimer’s disease and some have suggested that there may be some cause-and-effect relationship with the two, but I haven’t seen or read anything very convincing on that idea. Keep in mind that aluminum is a very commonly used metal for making all sorts of cooking utensils. If you don’t need an outlet valve and don’t use caustics, an aluminum kettle is fine.
The granddaddies of all kettles are ones made from copper. These dudes look great, have the highest thermal conductivity of all metals and are traditional. However, copper is expensive, difficult to weld (soldering is typically used on copper and this is easy) and is not inert. Copper not commonly used anymore for making big pots. I hope you didn’t have your heart set on copper! Those are some ideas on kettles. One option many homebrewers take is to convert an old beer keg into a kettle. These make good kettles, but I feel obligated to remind everyone that stainless-steel beer kegs are the property of breweries. The paltry $10 deposit is only a small fraction of the true cost of a beer keg. If you use a keg for a kettle, make sure you buy the keg from its true owner and help prevent keg float shrinkage! (Breweries refer to kegs out of the brewery as a “keg float.” Shrinkage refers to theft. What I’m trying to politely say is, give breweries a break and don’t steal kegs!)
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