Order of activation in a multi-function product

sg_sg_ Member
edited September 2020 in Formulating
1) There are multi-function products whose functions need to happen in a certain order. For example, a cleanser and shaving cream would need to clean before providing a moisturized, slick surface with a layer of cushion or foam. How does the formulation  ensure that such an order is achieved? Naively, one would not want the slickening ingredient to spread first and preventing the cleaning agent from getting to the grim or from removing the slick layer on the grime.
2) As another example, suppose good results are seen when three ingredients, a water based ingredient H, an oil A, and an oil B are applied in the order H followed by A followed by B.  How would one create a single topical product containing H, A and B such that on application, H goes on first, followed by A followed by B?
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  • 1) Traditional shaving creams are soap based, so they will provide both functions to an extent - when the excess cream/foam is rinsed off, I imagine it will take with it a significant amount of any dirt/oil that as present on the skin. I suppose the answer here is that you haven't got too separate ingredients in the formulation, one to lubricate and one to cleanse - rather, the formulation as a whole preforms both functions.

    2) I imagine the best method here is a straightforward oil-in-water emulsion. In this case, the aqueous phase is the external phase, and so H will get to the skin first, and then as the aqueous phase evaporate A and B will form a layer on the skin, along with any other materials in the oil phase. I'm not sure you could arrange it to get A then B instead of both simultaneously though. 
  • PerryPerry Administrator, Professional Chemist
    This is a good question. The marketing of raw materials and products makes it seem like you can get everything done in one product. The reality is that multi-function products don't work as well as single products used in series.

    If you have hair tresses you can do a simple test to show this is true. Wash it with a regular shampoo, then apply a conditioner.  Then comb the hair. Wash another tress with a 2-in-1 shampoo (e.g. Pantene) and comb the hair & compare. The shampoo+conditioner system will work better than the 2-in-1 shampoo.

    1. I agree with @LincsChemist. The ingredient that cleans & provides lubrication are the same. As long as the ingredient is on the face it is lubricating, then when you rinse it off it cleans.

    2. I'm not sure this general description is specific enough to give any kind of answer. What is are the "good results" that you would be referring to? A specific example would be more helpful for answering.

  • sg_sg_ Member
    edited October 2020
    The context is products to help with shaving. Here's a video Understanding the Chemistry behind Wet Goods Used During a Shave

    My understanding of the functions needed by the products is:
    1. Cleaning -- the stuff that needs to be cleaned off the face would include dead skin, salts from sweat, prior cosmetics, spills (food, beverages) etc.,
    2. Hydrating the skin (make it plump and stretched out, spread the follicles) and hair (so it is engorged) -- besides specialized hydrating products, drinking water, hot-wet towels (that add water on the surface and cause water to be brought to the skin and hair as sweat) and steam can help here,
    3. Sealing the hydration (I think this is termed moisturizing) and making the skin slick/slippery
    4. Creating a layer that would be scraped by the blade. This need not be foam/lather; it just needs to be a layer of slippery substance that is cohesive (does not drip).
    For steps 2 to 4, I have been experimenting with essentially single ingredients:
    • For (2), aloe vera on wet face
    • followed by a thin layer of Argan oil (which makes the skin very slick and, unlike coconut oil, does not make the stubble stick to itself or to the skin);
    • followed by jojoba oil.
    The above concoction does allow me to shave -- even just aloe vera on water followed by jojoba is very good for shaving. And I know, experimentally, that cleaning followed by jojoba does not help with shaving -- aloe vera over water is required before the oil.

    But I sure would like a better understanding of the interaction between the ingredients and the skin and stubble -- for example, is the argan for (3) really helping in any way?
  • cause water to be brought to the skin and hair as sweat. -  I am 99% sure sweat can not be brought back in to skin. 1% error for I may haven't read newer text or study.
    https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6773238/
    https://www.sciencedirect.com/topics/medicine-and-dentistry/sweat-gland-function

    I'm skeptical of using aloe vera and a thin layer of oil or the product you shared above before/during shave will provide more benefit than other lubricating agents like KY jelly, shaving cream.

    wet towel 5-10 min with shaving creams would be enough to make your hair soft and easier to shave.

    or if you are using aloe vera, Argan oil or Jojoba as an leave on after-shave for soothing micro tears causing by blade that might help.
  • PerryPerry Administrator, Professional Chemist
    My comments on the video.  While I'm sure the presenter has lots of experience of what works for him, the information is biased and his explanations for why things work are not supported by science.  It sounds like his education on why things works came from product marketers, not scientific studies. For example...

    A.  He says "you have to balance the pH of skin..." and then explains the problems with not having a "balanced pH".  This is marketing speak and this explanation is not supported by science. There are no studies looking at the pH of skin (which isn't technically a thing anyway) and the ability to absorb or reject products.

    B. "Glycerin is going to swell the hair" - No. Hair will swell when exposed to water because it absorbs water. Glycerin will not have any significant impact on the swelling of hair.

    C. Use of oil - Adding an extra layer of oil below the shaving cream is adding lubrication that you don't need. If you are using a good shaving cream that is formulated properly, it will provide all the lubrication you need for shaving. Adding the oil simply gets in the way of the function of the shaving cream. You are essentially trying to shave a "dirty / oily" surface. Adding oil negates the initial cleansing.

    To your points...

    1. Cleaning your face with a standard cleanser would be the most efficient thing to do. However, unless you have a particularly dirty face, you don't need to clean your face first. When I shave, I don't clean my face first.  The shaving cream is made of surfactants which will also help to clean the face. But you may get a nicer shave or you might enjoy the experience if you clean your face first. It just isn't really required.

    2. Simply putting water on your face is all the hydration you need. You do not need additional products. They will also not help the hair swell more than by just using water. Marketers have convinced people they need extra products when they don't really need them. 

    3. You don't need to "seal hydration."  The shaving cream provides all the lubrication you need. No oil sealant is needed. In fact, it will likely interfere with the function of the shaving cream.

    4. The creation of this layer is done by the shaving cream. No additional products are needed.

    If your three ingredient solution works for your skin, then that's great. Keep using it.  However, you can get the same or likely better results by just using a standard shaving cream. This really isn't that complicated.

    Truth be told, unless I have a few days of stubble, I shave in the shower using the warm water + the razor and nothing else. I may or may not wash my face before shaving. I don't get razor burn and it works fine for me. Using shaving cream generally makes it a bit less painful & more enjoyable experience, but just using the water is perfectly fine for me. 

    Product marketers have a habit of making things seem much more complicated than they actually are.

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