When I started as a hair care formulator in the cosmetic industry, Pert Plus shampoo was the number one selling brand. Consumers loved its two-in-one shampoo plus conditioner technology and nearly every other brand tried to copy it. This was made difficult by the fact that the technology was patented. However, suppliers and competing brands came up with numerous ways to get a conditioning effect from a hair cleaning product. Some were more successful than others.
Over time, consumers soured on the idea of a shampoo plus conditioner so two-in-one products became much less prominent. But the technology that powered two-in-one shampoos remained and today most moisturizing shampoos are actually two-in-ones.
Technology
Two-in-one shampoos target the consumer need for convenience, replacing a two-step process with a single product. They also are appealing to consumers who find standard conditioners too “heavy” for their fine, thin hair.
Unfortunately, it can be challenging to create a good working two-in-one formula because shampoos and conditioners have opposite goals. When shampooing, the aim is to remove dirt and oily materials from hair. When conditioning, the goal is to leave oily materials behind. Another problem is that shampoos need to produce a nice foam during use, and most non-cationic conditioning agents reduce foam quality.
The standard conditioning ingredients like cationic surfactants, humectants and emollients are not generally effective for a few reasons:
- Cationic surfactants are not compatible with anionic surfactants
- Humectants are water soluble and just rinse away
- Emollients are oils which get removed with all the other oils during washing
Early attempts at combining cationic surfactants with amphoteric detergents resulted in a product that didn't clean well, had undesirable foaming properties and caused build-up upon repeated use.
One of the first successful strategies was a formula that combined anionic surfactants with cationic polymers. It was found that, at the right ratio of surfactant to polymer, the two could be made compatible in a single system. Then upon use, the product is diluted, and the cationic polymer then becomes insoluble and precipitates out on hair. This dilution/deposition technology is still used today most commonly employing Polyquaternium 10.
But cationic polymers were not able to deliver the dry conditioning characteristics that consumers wanted, so development continued. The most significant advance came when formulators were able to successfully incorporate non-volatile silicones such as Dimethicone into shampoos. A number of patents were filed for incorporating silicones in shampoos starting in the 1960s. But the technology didn’t show market success until the 1980s, when P&G patented a blend of anionic surfactants, silicones and other ingredients using a special manufacturing procedure. It became the basis of a number of top-selling shampoo brands.
Formulations
Today, most two-in-one shampoo formulas are based on anionic surfactants blended with a combination of both a cationic polymer and a silicone polymer. The cationic polymer provides excellent wet hair conditioning while the silicone provides dry hair benefits. Some common ingredients:
Surfactants
- Sodium (or Ammonium) Lauryl Sulfate
- Sodium (or Ammoium) Laureth Sulfate
Sulfate-free Surfactants
- Sodium lauroyl sarcosinate
- TEA-dodecylbenzenesulfonate
Cationic polymers
- Polyquaterium 10
- Polyquaternium 15
- Guar Hydroxypropyltrimionium Chloride
Silicones
- Dimethicone
- Amodimeticone
Aesthetic-enhancing additives
To improve the aesthetics of the shampoo, formulators use a number of other ingredients. To get a creamy, rich lather foam, boosters are incorporated into the formula. This is usually a fatty acid alkanolamide like Cocamide MEA or a betaine such as Cocamidopropyl Betaine. Since consumers expect moisturizing or two-in-one shampoos to be opaque a pearlizing agent such as Glycol Distearate may be used. And of course ingredients like dyes, fragrances, preservatives and feature ingredients can also enhance consumer appeal.
The two-in-one shampoo technology remains popular with consumers and brands even though it isn't often marketed as such. In my lab evaluations, these products still do not quite match the performance of a shampoo and conditioner done in separate steps, but they certainly have gotten better.
In the future formulators may incorporate other benefits from shampoos such as hair coloring or hair styling. Technical challenges to products like these remain, but with enough consumer demand, companies will be motivated to better develop this technology, too.
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Good resume Perry. Compact and easy to understand.
perry, thanks for sharing your knowledge.
Hi Perry,
can it be assumed, that, when using a previously diluted shampoo formulated with coacervates, the conditioning polymers deposit before the surfactants could finish their job?
I would suggest that the precipitation step would start earlier in already diluted shampoos, maybe leading to product build-up near the roots?
Sorry, I’m not really sure I understand your question. If the product is diluted then the polymer will start to separate prior to use. But yes, this problem could lead to build-up
Maybe a languagebarrier issue. But I think you have unterstood me. 🙂
Thanks for answering my question.