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Aluminum vs stainless

Discussion in 'Homebrewing' started by Hotmetal1, Dec 5, 2012.

  1. Hotmetal1

    Hotmetal1 Member

    Location:
    Mississippi
    I have my first batch of beer in secondary and used an aluminum pot for a boil kettle. A friend told me I shouldn't have used aluminum but at the time I didn't have the money for a nice S/S brew kettle, the 10 gl aluminum pot was free. Should I save-up for S/S or will I be fine with what I have. I pulled a sample of beer to test gravity yesterday and it tasted fine to me (didn't taste like metal).
  2. cmmcdonn

    cmmcdonn Member

    Location:
    Virginia
    Though not as durable, aluminum is fine as long as you create a passive oxide layer. You can do that by filling your kettle with water and boiling for ~30 min. You'll notice a discoloration when you're done. That's what you want.

    You also shouldn't use harsh cleaning products on aluminum because it will strip that oxide layer and you'll have to do it over.
  3. Hotmetal1

    Hotmetal1 Member

    Location:
    Mississippi
    Thanks, that what I was hoping to hear.
  4. WickedSluggy

    WickedSluggy Member

    Location:
    Texas
    Aluminum is inferior to SS, but it will work fine for a boil kettle. It's cheap, and it's nice and light. As cmmcdonn noted, be carefull with your cleaning process. Aluminum reacts quickly with hydroxides, so never use lye or oven cleaner Etc. I don't even recommend oxy clean (percarbonate). If you leave it in contact with alluminum for long it will create a messy black layer. It can be removed with acid, but then the alluminum has to be re-passivated.
    Hotmetal1 likes this.
  5. ditch

    ditch Member

    Location:
    Virginia
    Do not scrub it! Soak and Wash with a gentle soap and sponge. It will last a long time if you take care of it. I've been using a 15 gallon aluminum pot for 3 years as a hot liquor tank and it still doesn't show any ware.
    Hotmetal1 likes this.
  6. mikehartigan

    mikehartigan Member

    Location:
    Illinois
    not to start an argument, but inferior in what way? Aluminum has some distinct advantages over SS, among them price, weight, and thermal conductivity (very important when used as a cooking vessel - that's why most commercial kitchens use Aluminum cookware). In the context of home brewing, I'm not aware of any clear advantages of SS over aluminum.
    geezerpk and bwiechmann like this.
  7. jamescain

    jamescain Member

    Location:
    Texas
    I have only used Aluminum and have not noticed any discernible differences. To clean I have a plastic brush that I use to scrub with so that I don't scratch the kettle. SS is nice because of it is more scratch resistant. The advantages of Al is its heat conductivity, price, and the fact that its lighter. Oh and SS is fancier I forgot to add that part. You're fine with Al as long as you have an oxidized layer built up.
  8. WickedSluggy

    WickedSluggy Member

    Location:
    Texas
    Yeah, I know, this dead horse has been beaten into hamburger by now. You took the bait. Ha!

    No, for a simple boil kettle there are no major disadvantages. However, I don't know if thermal transparency is a good thing for a BK. The trilaminar kettles (stainless with a middle layer of copper or aluminum) are probably best for preventing unwanted maillard reaction and darkening of wort. It is really once you start adding fittings, valves, false bottoms Etc, the durability and non-reactive qualities of SS becomes more important.
  9. WickedSluggy

    WickedSluggy Member

    Location:
    Texas
    Hmmm?
    hopfenunmaltz likes this.
  10. GregoryVII

    GregoryVII Member

    Location:
    Michigan
    They aren't as shiny. I like shiny.
  11. jamescain

    jamescain Member

    Location:
    Texas
    As in a metallic taste or difference from a commercial SS fermented beer. I see now that my post was confusing.
  12. DOCRW

    DOCRW Member

    Location:
    Washington
    I have brewed with both and I can tell you that SS does have an advantage over aluminum. The biggest one is it's obvious hardest with protects against released tarnish from the aluminum if scrubbed with immersion chiller or during the first uses of the kettles. If you have the money and plan on brewing a lot of beer get the SS, if you are dead set on cost than do as you must! Weight shouldn't be a factor since there really isn't one and is a poor reason to own one over another. Another thing to consider is dissimilar metal with attached options like thermo and weld-less ports....
  13. VikeMan

    VikeMan Member

    Location:
    Pennsylvania
    I'm gonna go out on a limb and guess that the OP has already made his decision on this, given that he was asking over a year ago.
    jmw, JrGtr and WickedSluggy like this.
  14. ryane

    ryane Member

    Location:
    Washington
    This doesnt really make it inferior, maybe easier to work with?, but you can solder SS with silver solder. This allows you to attach fittings to the kettle without using gaskets.
  15. WickedSluggy

    WickedSluggy Member

    Location:
    Texas
    Aluminum is good. Stainless is gooder
  16. skivtjerry

    skivtjerry Member

    Location:
    Vermont
    The big (really only) advantage of stainless is that it's easier to clean - you can use harsh stuff that would damage Al.

    Stainless is more durable, but a kettle made of either will last several lifetimes unless you back your truck over it or something similar.
  17. AlCaponeJunior

    AlCaponeJunior Member

    Location:
    Texas
    I realize this thread is old, but I will toss in my 2 cents anyway. I have both and use both.

    Thermal conductivity: makes big a difference if you don't have enough heat in the first place. Otherwise it probably means little, other than you'll spend a few cents more on propane or NG, and have to wait a couple minutes longer when reaching mash or boil temperatures each brew day. If your budget is so small that this is a big deal, then maybe you shouldn't have such an expensive hobby. Dig those quarters out from under the seat of your '69 dodge pickup truck and get you a nice 40 oz. If your time is so precious that this will make a big difference, then get over yourself already, because you're probably not nearly so important as you think you are. :rolleyes:

    I use a soft plastic dish thingie to clean the aluminum pot. Hasn't caused any problems. About every 6-7 batches I boil about a gallon of water for a while, just to make sure the oxide layer is intact, and to make sure the pot is good and clean.

    Weight is also a pretty silly thing to break the deal over. If carrying the pot empty means straining your back with stainless, but not with aluminum, then you should keep the number for the ambulance handy for those times when you buy a commercial six pack, and have to carry it from the store to your car, because a six pack is certainly going to be heavier than a brew pot for a five gallon batch.

    If you intend to drill holes / install attachments like valves, thermometer sleeves etc, then different metals in contact with each other = bad, so go stainless, because I don't think you'll find many aluminum components.

    Durability doesn't make much difference if you take care of something properly. Although I did drop one of my aluminum pots, and it's got a pretty good little 2" dent in it now. Meh, it fits fine on the turkey fryer burner it came with, so big deal.

    Price is cheaper for aluminum. Initial cost for a noob could be a big factor if one way leads to a stainless pot that's too small, but the other leads to an aluminum pot that can handle a full boil no problem. Full boil = gooder.
  18. geezerpk

    geezerpk Member

    Location:
    South Carolina
    I've used aluminum for 3 years or more. Some say the aluminum can lead to Alzheimer's, but dang if I can remember the reason why.
    bgjohnston likes this.
  19. hopfenunmaltz

    hopfenunmaltz Member

    Location:
    Michigan
    For Alcaponejr

    You haven't had an engineering heat transfer class, have you?
    The difference in time in negligible due to the overall heat transfer equation. The weak link is getting the energy from the gas to the metal, and metal to liquid is not high heat transfer either. I actually timed 2 pots, one AL and one SS while heating. The SS was quicker. This is counterintuitive, by my guess is that it has to do with the surface finish the SS=shiny and he AL=dull. There is a something called the wetting property of a metal, SS and AL are about the same, but many small imperfections would allow a film layer of water vapor to build up, which has a low conductivity. Someday I might repeat that, then polish the AL to a mirror finish and see if it would do better.

    Copper has much better conductivity and wetting properties than either. That explains the traditional copper kettles until cost, the use of steam, and durability with modern caustic cleaners became and issue.

    For all those that will say but but but, AL has a higher conductive heat transfer coefficient, there is an example here that says for air to air media you might as well use plastic rather than SS or AL.
    http://www.engineeringtoolbox.com/overall-heat-transfer-coefficient-d_434.html[/quote][/quote]
    DOCRW likes this.
  20. AlCaponeJunior

    AlCaponeJunior Member

    Location:
    Texas
    well it seems that in light of new information, I will have to re-evaluate my beliefs and adjust them according to better evidence and more accurate information.

    Or, I could just do like the republicans, and continue to insist that the world is flat, and glow-ball warming doesn't exist, because it's all a diabolical plot by the EPA to kill jobs. That way I would never have to admit that I was wrong, or change my rhetoric to coincide with the actual facts. :rolleyes:

    The buffer of just-starting-to-boil liquid (turning to gas) on the bottom of a pot, and its being more prevalent on an aluminum pot (which presumably has an oxide coating if you conditioned it, thus having more nucleation points), gives a very reasonable explanation as to why stainless might boil faster, despite the higher thermal conductivity of Al. It is feasible that this factor could be more significant in the boil time of water/wort than thermal conductivity alone. It's certainly believable that if you scrubbed an Al pot as clean as a stainless one, the water could boil faster, although doing that would remove your protective oxide coat, which you would then be re-establishing by boiling water, so... oh forget it. :p

    And no, I won't be taking that particular class. I changed majors to tree-hugging-hippie-ism (i.e. environmental science). Stinkin' dirty hippies! I'm a fucking metal-head, how did I get roped into this? :rolleyes:

    I'm only taking a math minor to torture myself. Calculus III anyone? o_O
  21. skivtjerry

    skivtjerry Member

    Location:
    Vermont
    [/quote][/quote]

    Did the two vessels have the exact same geometry? That can make a huge difference, regardless of the metal. Exact same burner too, right? And ambient temperature, wind etc.?
  22. skivtjerry

    skivtjerry Member

    Location:
    Vermont
    Buck up... my calc III was easier than the 2nd semester. Differential equations did whup me pretty good though.
  23. hopfenunmaltz

    hopfenunmaltz Member

    Location:
    Michigan
    [/quote]

    Did the two vessels have the exact same geometry? That can make a huge difference, regardless of the metal. Exact same burner too, right? And ambient temperature, wind etc.?[/quote]
    Yes they were very close in geometry, the burner was not changed, on pot was off and the other was put on. The 40 LB tank was almost full. It was the SS pot first and the AL second. I measured from 100F to 200F to take any initial differences out, and deciding when it was boiling out. Not what I expected at all. From some calculations of overall heat transfer I thought the AL would come to temp faster, maybe about 30 seconds. It was slower.
  24. skivtjerry

    skivtjerry Member

    Location:
    Vermont
    Did the two vessels have the exact same geometry? That can make a huge difference, regardless of the metal. Exact same burner too, right? And ambient temperature, wind etc.?[/quote]
    Yes they were very close in geometry, the burner was not changed, on pot was off and the other was put on. The 40 LB tank was almost full. It was the SS pot first and the AL second. I measured from 100F to 200F to take any initial differences out, and deciding when it was boiling out. Not what I expected at all. From some calculations of overall heat transfer I thought the AL would come to temp faster, maybe about 30 seconds. It was slower.[/quote]

    Interesting. I feel like pulling out some cookware and playing around. This could make a good geeky Zymurgy article.
  25. hopfenunmaltz

    hopfenunmaltz Member

    Location:
    Michigan
    Yes they were very close in geometry, the burner was not changed, on pot was off and the other was put on. The 40 LB tank was almost full. It was the SS pot first and the AL second. I measured from 100F to 200F to take any initial differences out, and deciding when it was boiling out. Not what I expected at all. From some calculations of overall heat transfer I thought the AL would come to temp faster, maybe about 30 seconds. It was slower.[/quote]

    Interesting. I feel like pulling out some cookware and playing around. This could make a good geeky Zymurgy article.[/quote]
    Yes, a Zymurgy article has come to mind.
    DOCRW likes this.
  26. Marshall_ofmcap

    Marshall_ofmcap Member

    Location:
    Colorado
    linear alg. was the one that got me. never took diff eq but i did hear horror stories
  27. utahbeerdude

    utahbeerdude Member

    Location:
    Utah
    Ah, Calc III. Definitely my favorite freshman-year class. I remember it well. Well, maybe not so well as that was 36 years ago. Still, who doesn't like Green's theorem?
  28. VikeMan

    VikeMan Member

    Location:
    Pennsylvania
    <raises hand>
  29. Marshall_ofmcap

    Marshall_ofmcap Member

    Location:
    Colorado
    the drop out (read me)
  30. AlCaponeJunior

    AlCaponeJunior Member

    Location:
    Texas
    Green's and Stoke's theorems aren't for about 7-8 more weeks. Lucky for me I've taken linear algebra, or cal III would be much more of a bitch.
  31. Marshall_ofmcap

    Marshall_ofmcap Member

    Location:
    Colorado
    i took them together, didnt help me, not much can though
  32. ssam

    ssam Member

    Location:
    California
    I'm a math major. Yea...

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