What happened to my espresso maker?

May 19, 2007 10:46 AM

What did my dishwasher do to my stovetop espresso maker??

I purchased a relatively inexpensive stovetop espresso maker and decided to wash it before use. When I removed it from the dishwasher this morning, there was a bizarre powdery substance all over it. What is that, and how do I get rid of it?

posted by jefficator to food & drink (14 comments total)

I bet your espresso maker is anodized aluminum and from what I can tell looking around online, that stuff doesn't fare well under the used of dishwasher detergents.

http://www.cleaning101.com/dishwash/dishwashing_fact_sheet5.cfm

"Aluminum, with a colored or metallic copper or gold look usually on the lids of pans and molds, has a thin anodized coat that is not dishwasher safe. "
posted by smallerdemon at 11:04 AM on May 19, 2007

I checked that link, smaller, and it mentioned steel wool for cleaning aluminum. Is there a difference between anodized aluminum and regular aluminum?
posted by jefficator at 11:09 AM on May 19, 2007

Googling around a bit shows that a lot of the inexpensive ones are made of aluminum. Does your mystery substance leave a black rub-off on your fingers when you touch it? If so, I'd guess it's aluminum oxide, and your dishwasher gave it a bit of a shockingly fast oxidizing.

You could try soaking it in vinegar solution for a little while, and then washing it by hand in soapy water. Don't leave it hanging around wet, dry it thoroughly afterwards. Try sticking to washing it by hand, instead of in the dishwasher.

Aluminum loves it some oxygen, so there's not much you can do at home to in terms of treatments to prevent it. Unless you have an anodizer handy.

On Preview: Anodized aluminum is usually coloured.
posted by CKmtl at 11:20 AM on May 19, 2007

From anodizing.org:

CLEANING ANODIZED ALUMINUM

Can anodized aluminum be cleaned with a detergent that has a pH of 10, or would that result in scaling or other surface problems?

Factors such as concentration of the detergent solution, duration of exposure, and temperature will influence the results. If the anodized aluminum is cleaned at room temperature and promptly rinsed with clean water, then there should be no problem. If cleaned at an elevated temperature or with prolonged exposure without rinsing, then the cleaning solution would start to attack the anodic oxide and etch the metal. Mild soap is generally preferable to detergent for routine maintenance cleaning.

How do I clean anodized aluminum?

Cleaning anodized aluminum is easy with the right technique. Because anodizing is so hard, you want to use an abrasive cleaning technique with a gentle soap. Do not use harsh acidic or alkaline cleaners because they may destroy the finish. Use solvents with care as they may stain the finish. Regardless of the technique, be sure to try a test area first. One recommended technique is to use an abrasive cleaning sponge with mild dish washing liquid. Always try a test small area first to prevent a widespread problem.

Hope this helps.
posted by ikkyu2 at 11:20 AM on May 19, 2007

After reading a little more about anodising if may be the opposite. That your make wasn't anodized. I am sort of just guessing, if course.

It sounds like whatever it was made of that it really didn't like the strong detergent used in your dishwasher, though. :(

Detergents are not acidic, of course, but usually they are VERY basic.

I found this thread describing nearly an identical thing. Which leads to this about lime deposits.

How old is your dishwasher? Maybe it's got lime deposit issues. Do you notice any of the other symptoms they talk about on that link? (Cloudy glasses, etc.)
posted by smallerdemon at 11:27 AM on May 19, 2007

There is a black residue that comes off on my fingers. Maybe steel wool and vinegar?
posted by jefficator at 2:32 PM on May 19, 2007

Dishwashing detergents generally have a fair amount of chlorine bleach included in their formulations as a sanitizer (anti-bacterial). This is also a strong oxidizer, and aluminum oxide is, perhaps coincidentally, black, and will tend to rub off uncoated aluminum rather easily, although it does form a protective coating on bare alumininum that will retard the formation of additional oxide, if left undisturbed. So, I'm betting that your aluminum utensil was either not anodized, or anodized with a process which left a fairly thin, porous anodized coating, which is now destroyed. Your utensil will likely, then, continue to form new aluminum oxide continually, as use continues to expose fresh aluminum, and oxygen continues to oxidize that fresh aluminum, which will then flake away microscopically, exposing fresh aluminum, etc., etc. Used as coffee carafe utensil, exposed aluminum surfaces generally have a coarse enough metallic grain structure to trap oils and sediments, which are also acidic, and react badly with these. It's far from a desireable situation for making consistently good coffee.

Unfortunately, aluminum oxide is also a fine abrasive, because it is both very hard and because its crystalline structure is stable and forms sharp edged particles, which are good at abrading other materials. This makes aluminum oxide the #1 abrasive material by weight in abrasive applications, where it is the cutting material in most industrially manufactured grindstones and sand paper.

You don't want to ingest a lot of aluminum oxide, not because it is particularly poisonous, but because it is hard and abrasive. And you don't want to put utensils which form aluminum oxide through your dishwasher, because that black residue will quickly grind up water pumps and plastic bearing surfaces just as easily as if you were sanding them with fine grit sandpaper.
posted by paulsc at 3:09 PM on May 19, 2007

I'd advise against steel wool. Steel is harder than aluminum, and you could end up scratching the hell out of your new kitchen toy. Handwashing should get most of it off, maybe a plastic scrubber thing for the tough spots. Only use the steel wool as a last resort.

Oh, and check any rubber gaskets (it's been a few years since I've used one of those stovetop pots, can't remember if there's rubber gaskets) for deterioration from having been in the dishwasher. If they've cracked or gone crumbly, you'll need a new one.
posted by CKmtl at 3:23 PM on May 19, 2007

If it's the kind I think it is, it almost certainly is non-anodized aluminum. That's consistent with the powdery stuff.

Scrub all that stuff out of there and rinse it well. Use vinegar if you want. Then look here (scroll down) for tips on seasoning the pot, Italian style. Once you do that, you'll never have to scrub again.
posted by Opposite George at 3:29 PM on May 19, 2007

Oh, in case it wasn't obvious, never put that pot in the dishwasher. You'll be fine.
posted by Opposite George at 3:32 PM on May 19, 2007

George,

That is the kind, yes. But I think mine is aluminum instead of stainless steel. The price and this situation seems to suggest as much...
posted by jefficator at 5:18 PM on May 19, 2007

The ones in the first link are aluminum, too (well, the ones at the top of the page, anyway) -- just polished on the outside so they look like steel. I've seen 'em both polished and not but almost always aluminium regardless...

The second link shows a stainless steel pot at the top, but (and this is why you need to scroll down) discusses care of aluminum pots at the bottom of the page.

Good luck with the pot!
posted by Opposite George at 7:26 PM on May 19, 2007

Aw jeez, did I say "aluminium?" Well, it is talk like a Brit flyboy day...
_{Tally Ho!}
posted by Opposite George at 7:28 PM on May 19, 2007

Approximate characteristics of native aluminum oxide: white crystalline powder.
[Merck Index; 12th ed. P.63]

Anodized aluminum has a layer of oxide which has been thickened by an electrochemical process, but any aluminum surface in air immediately develops a layer of aluminum oxide which protects against further oxidation at room temperature.

Ruby and sapphire are crystalline aluminum oxide, colored red by traces of chromium in the case of ruby and iron in the case of blue sapphires. Without those impurities they would be water white (if not whiter).

Corundum and Alundum are abrasives which are primarily aluminum oxide; corundum is directly mined and is usually brown to gray; alundum is bauxite which has been fused in an electric furnace and contains various impurities, including iron oxide.
posted by jamjam at 7:53 PM on May 19, 2007