How do you formulate a product [by example]

I've been asked how I go about formulating a product.

I feel like that's a good question, so I'm going to use my cleansing balm as an example. I'm still doing trials (I mean, that's true of everything, but this is quite new) so things could potential change, but the basic idea should remain the same.

A cleansing balm is like an oil cleanser (as opposed to a soap cleanser) because it is primarily comprised of oils and an emulsifier.

[a random article on how emulsifiers work: https://www.gcsescience.com/o77.htm ]

As you can see from the link above, an emulsifier works to make oils and waters mix by having itself two separately attracted ends: one side attracted to oil, one side attracted to water.  This is different from a physical emulsification which is almost always significantly less stable. Like having to stir up your all natural peanut butter, or any product that says 'shake before use'.

The reason you want an emulsifier in an oil cleanser is because you obviously wouldn't be able to rinse off an oil with just water, as oil is hydrophobic. That's why oil cleansers (if you've ever used one) do that 'soaping' thing, where they turn white as they run off. I always wondered about that until I realised I probably knew enough science to make one and sure enough, there's a whole word for that effect!

Alright, so now you know how oil cleansers work, I assume you already have experience with surfactant and soap based cleansing. :P

So, mine has a complete emulsifier and a liquid foaming solubiliser as well. It also has very cheap oils (I'm talking EVOO [extra virgin olive oil] type cheap, you guys) because you're just going to rinse them off, and lemme stop you right there; it does not have coconut oil because my skin does not like coconut oil (my hair loves it, however.)

An emulsifier that I own, but not this brand

A solubiliser I own, also not this brand

Boi if you don't know what this is

That's really the basics, because as far as I know, most complete emulsifiers are generally solid at room temperature, as long as you don't add too much oil, it should work.  I guess I would add, maybe don't use a cationic complete emulsifier, as that would probably try to stick around on your face, and this is a product you're hoping will wash off and take all the gunk with it.
However, I also have some other thickeners (my home is hot, my products become very solid at non-lizard-people temperatures.  This really sucked for my lotion back in college, heh.) and some other cheap oils, to improve the consistency, as well as a flavour oil.  I've also added some skin nourishing ingredients as well. I use flavour oils because I always wear extremely life-resistant lipsticks that require a ton of extra omph from my products, and I did the first trial without it. In case you didn't know, oil in ya mouth is pretty grody.

Live photo of Lil Red with an oily mouth

I also add mica because sometimes you gotta treat yourself, okay?

One shiny boy

Because this product contains no water, you do not need a preservative, unless you're double dipping or keeping it somewhere very wet. I usually add vitamin E oil to all of my oil based products.

*Always preserve your products, with real preservatives and not just some bs like essential oils.  It is not worth the chance of rubbing bacteria directly onto your skin to not use it unless you are literally making immediate use batches for testing and nothing else.  It doesn't matter if it looks okay, products can look fine and not be fine.  You wouldn't eat moldy bread, right?