On any number of cleansing products in my home, both those for body and house, the label says that one of the main ingredients is a foaming agent such as Ammonium Laryl Sulfate, Sodium Laureth Sulfate, etc. All queries as to why such chemicals are added yield the answer that foam sells cleanliness.
Why?
Since the foaminess must be added, presumably the product would clean just as well without it, and you’d get more cleanser per bottle. It’s always seemed strange to me that we feel it necessary to add the foam, since presumably the actual cleaning agent is already known to clean without it?
Where did the notion originate that a substance must bubble up for it to get things clean?
Other than crude agents like scrubbing with sand, soap (lye and fat) was one of the first cleaning agents. It makes bubbles. Not huge billows, but some. Use more soap, get more bubbles, and presumably, get cleaner.
So now, everything has to have bubbles so we think it’s doing something and getting our whatever clean.
Of course, there are applications where the cleaning happens in a “black box” and bubbles just cause problems. (Dishwashers and clothes washers leap to mind) In these applications, anti-foaming agents are sometimes employed.
The foaming agent is the main cleanser. It’s the soap or detergent in soap and detergent.
Foaming occurs with a reduction in the surface tension of the fluid caused by soap or detergent.
Cleaning occurs as a result of the amphipathic nature of soaps and detergents; able to dissolve in water while able to create microdomains (micelles) wherein hydrophobic molecules (grease, oil, proteins) can happily live. A detergent in water solution can dissolve both hydrophobic as well as hydrophyllic substances making it a better solvent than plain water.
Plenty of industrial solvents don’t have bubbles – alcohols, acetone, etc. And it’s not just limited to industry. You used to be able to buy “dry cleaning” fluids. Unfortunately, a lot of these were things that are now known to be dangerous (carbon tetrachloride, for instance), so most home cleaners these days do tend to be bubbly.
No, it is generaly considered that there is NO direct relationship between foaming and detergency in ordinary fabric washing systems. Foam can be benificial in cleaning carpets, where it physically takes up the dirt particles from the carpet and hold them there to prevent redeposition - a bit like froth floatation.
Sudsing type surfactants are not used in front-loaders because the foam ‘cushions the impact’ of the clothes as they tumble around, thus decreasing the cleaning action.
The foaming action is dependent on the type and mix of surfactants in the detergent - if you add a little soap the bubbles collapse quicker.
Basically foaming agents are added so people think the stuff is working and buy it. The foam is a visual cue and consumers are stupid.
Here’s my experience. I’ve worked with sodium dodecyl sulfate (SDS) solutions. SDS is a commonly employed detergent, a cleaning agent. The simple solution in water is foamy as hell.
Which cleaning agents foam secondarily rather than as a consequence of employing a detergent to assist the cleaning effect? Agreed that low-foaming detergents are used for specialized applications. My take is that these are second or third generation products.
All the ‘foaming agents’ listed are also detergents. Among the most effective detergents is sodium lauryl sulfate, but presumably it’s not foamy enough for household cleaning. ‘Foaming agents’ such as ammonium lauryl sulfate are really just high-foaming detergents. They may not necessarily be as effective as detergents as less foamy ingredients, but they still contribute to the product’s detergent effect. (Foaminess and detergent ability are not related, though.)
We agree that different detergents have different foaminess. I’m curious to find examples of marketing practices centered on increasing foaminess without affecting cleaning effectiveness to enhance consumer satisfaction.
I was recently (last week) using an expensive shampoo that, IMHO, wasn’t sudsy enough, I couldn’t feel confident that the amount of product I typically used was enough for all my hair. I’d use my normal amount, get some suds on the top of my head, and nothing on the sides. Is it just low foam, or did the detergent peter out? I can’t tell. Should I just trust that my hair is clean?
I switched to a cheapo brand, with plenty of ammonium laurel sulfate, identified below as a high foam detergent in contrast to the other brand which used sodium coco-sulfate, which I presume is a pretty low foam detergent. Maybe my hair isn’t really any cleaner, but I feel more confident that all of my hair got thoroughly shampooed.
Soap bubbles.
Back in the 60’s, one of the dishsoap manufacturers, Ivory IIRC, ran a long add campaign touting their brands longer lasting bubbles. No bubbles in the sink was equated to dirty dishes. Ivory was one of the first brands to include glycerin to their dishwashing liquid. Glycerin does nothing for cleaning, but it is “gentle on the hands”, and also prolongs the life of suds.
A first liquid detergent on the Australian market was Trix. It was non-foaming and was taken off the market because consumers didnt like the lack of foam.