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In Brazil, there is a soap paste ("sabao pastoso") commonly used to clean aluminum pots with steel wool. I'm guessing the benefit here, compared to normal liquid dishwasing soap, comes only from a higher soap concentration and the pastier consistency (to keep the soap from running downward during scrubbing). But, the paste is black and appears more complicated. Is there more physics here?

And, would there be any drawback (besides cost, since you tend to use more soap when it's more concentrated) in using this paste to clean ceramic plates with a normal sponge?

I'm not familiar with this pasty soap in the USA. We usually use the same liquid dishwashing soap for every surface...is this is a bad practice?

bobuhito
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Aluminum cleaners typically contain mild/organic acids and sometimes also contain abrasives, to help remove oxidation. The black color may very well be aluminum oxide which is a cleaning abrasive (a sensible choice for an aluminum pan cleaner). A paste is also sensible for aluminum pots because these pots require a rigorous scrubbing, compared with ceramic, teflon, and steel dishware.

However, most other cleaners are neutral or basic; and other common cleaning abrasives like silicon dioxide are white. Some cleaners contain oxidizers (like peroxides) and others contain reducing agents.

Dish detergent in the USA is generally made for removing/dissolving grease. We tend to use aluminum more for disposable aluminum-foil pans, and opt for stainless steel and/or other cookware materials, because other materials are simply better quality and require less scrubbing, and/or simply diswasher-safe (unlike aluminum which tends to become blackened by the oxidizing cleaners found in dishwasher soap).

Ben Welborn
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  • Aluminum pans does not mean aluminum foil pans. Many large-volume pots (generally for the purpose of boiling water or deep frying) are made out of aluminum. – Catija Aug 02 '16 at 15:31
  • @Catija I happen to have aluminum pans and (I believe) the paste in question. – Ben Welborn Aug 02 '16 at 15:32
  • @Catija I believe the point was that most people don't have a ton of aluminum pans here so we don't need the aluminum cleaner as much. Edited to clarify, hopefully. – Cascabel Aug 02 '16 at 15:40
  • @Jefromi yes, that's what I meant... but I re-edited replacing _just_ with _more_ – Ben Welborn Aug 02 '16 at 15:46
  • I don't believe my paste contains abrasives (at least the ingredients don't explicitly call it out). That leaves only the pH-balancing point in your answer. I can believe many normal dishwashing soaps do discolor aluminum (and worse, can lead to flaking and food safety problems), so my question then becomes, Why not just let this pH-neutral soap paste replace all dishwashing liquid in the USA? The paste has a nicer feel for me, so I'm thinking the only downside is higher cost. – bobuhito Aug 03 '16 at 05:44
  • @bobuhito I am not wanting to make this about a product... which is kind of tactless for stack exchange, but for what it's worth, toothpaste also does a very nice job for cleaning aluminum. But for washing dishes, presoaking is a common method, and a degreasing liquid detergent poured from a bottle seems to be pretty ideal for that. Paste on the other hand is really better for scrubbing, which is not recommended or necessary for teflon and ceramic cookware which is fairly common in USA... as are diswashers. – Ben Welborn Aug 03 '16 at 12:52