In response to yesterday's question-
" Hi, Kennece, apparently with "natural" emulsifiers there is no longer a need to calculate HLB value, like in the past. Provided the correct type of emulsifier is used, example O/W or W/O. Do you agree because if it is still relevant then it's important. I don't want to overlook it? To help me understand further, if a few oils are used, what happens to the HLB value then? Thank you for this deeper dive into Cetyl Alcohol.
The short answer to this question is - yes!
Whether using a natural or synthetic emulsifier, the HLB value is still relevant. HLB is not determined by a materials origin or processing it is determined by solubility. I am not sure if you read something or perhaps watched a video, but perhaps it is a reference to homemakers or DIYers having such a small selection of raw materials available to them, most emulsifiers being what is referred to as "All-In-One" emulsifiers. In such case, there is no need for a formulator to create an emulsification system, using the HLB method.
HLB - A Deeper Look
When browsing online for new ingredients, you’ve likely come across something called HLB, often accompanied by a number. Maybe you’ve read terms like "High HLB" or "Low HLB" while learning about the ingredients themselves. I know many DIYers aren't interested in diving into the science behind the raw materials we work with, but for those who are, you’re in for an insightful read.
To be completely transparent, I hated science in high school. In fact, I nearly failed it! I had a borderline mark of 50%. When my father found out, he wasn’t having it. I remember him locking me in my room with a textbook and a stack of lined paper, instructing me to rewrite the entire book over and over again until exams. I grew up in a time when the internet wasn’t at our fingertips, households didn’t have computers, and the TV shut off at a certain time of night. So, I wrote that textbook out, sat for the exam, and managed to get a 78%. I remember it like it was yesterday, but even then, I still didn’t enjoy science.
When I first started formulating, I didn’t associate making products with science. For me, it was like cooking or DIYing. However, with every failed product, I wanted to understand why it didn’t work—or, in the rare cases when it did, why it worked. When I started formal education in cosmetic chemistry, I was terrified. Honestly, I was. I was over 30, hadn’t been in school for years, and couldn’t recall much from those high school science and chemistry classes. But my love for formulating—that burning desire to understand the ‘why’—made science not only tolerable, but also interesting and fun.
There are many chemists with far more experience than I have, and I still find myself questioning certain processes, but the more I learn, the more things make sense. Eventually, it all becomes second nature. Hopefully, after reading this article, if you’ve ever stared at that HLB number and wondered what it meant, it will finally click!
Creating a Stable Emulsion Using the HLB System: A Step-by-Step Example
When formulating at home—whether you're DIYing or running a small business—the selection of materials available on a small scale is unfortunately limited compared to what’s available in large-scale production. Most small-scale suppliers carry what we refer to as "all-in-one emulsifiers." Occasionally, you may need to incorporate a co-emulsifier to stabilize certain materials, such as OliveM 1000, but it's rare that you'll need to create a stable emulsification system from scratch. I assume that suppliers offer these "all-in-one" emulsifiers to make it easier for DIYers to create stable emulsions.
Given this limited availability, I was somewhat restricted in the materials I could choose for today’s example. However, the Hydrophilic-Lipophilic Balance (HLB) system, developed by William Griffin in the 1940s, helps us determine which emulsifier is best suited for the oil phase of an emulsion.
What is the HLB System?
Each emulsifier consists of two parts: a hydrophilic (water-attracting) head, typically made up of a water-soluble functional group, and a lipophilic (oil-attracting) tail, often derived from a fatty acid or fatty alcohol.
The HLB system operates on the principle that emulsifiers with higher solubility in water are more suitable for oil-in-water (O/W) emulsions, while those with higher solubility in oil are better for water-in-oil (W/O) emulsions. In simpler terms:
Higher HLB values mean the molecule is more hydrophilic and water-soluble, ideal for O/W emulsions.
Lower HLB values indicate a more lipophilic and fat-soluble molecule, suitable for W/O emulsions.
The HLB System in Action: An Example
For this example, I’ve chosen two emulsifiers: Laureth-23 (HLB 16.9) and Sorbitan Olivate (HLB 4.7). These materials are readily available on a small scale for anyone interested in cross-referencing the HLB numbers or reading more about them.
This example is purely for educational purposes—I don’t recommend making this formula, as the lipids were chosen randomly to simplify the explanation.
Our Simple Formula:
Shea Butter 4% (HLB 7)
Jojoba Oil 4% (HLB 6)
Babassu Oil 4% (HLB 7)
Plum Oil 4% (HLB 7)
Cetearyl Alcohol 4% (HLB 15.5)Note: Cetearyl Alcohol is a fatty alcohol that helps thicken emulsions and improves skin feel, but for our purposes, it’s considered part of the lipid phase.
Distilled Water 70.5%
Liquid Germall Plus 0.5%
The total lipid phase in this formulation is 20%.
Step 1: Calculate the % Contribution of Each Oil in the Lipid Phase
To determine how much each oil contributes to the lipid phase, divide the percentage of each oil by the total percentage of the oil phase:
Shea Butter: 4% ÷ 20% = 0.20
Jojoba Oil: 4% ÷ 20% = 0.20
Babassu Oil: 4% ÷ 20% = 0.20
Plum Oil: 4% ÷ 20% = 0.20
Cetearyl Alcohol: 4% ÷ 20% = 0.20
Add them up, and you’ll always get 100%—this acts as a way to double-check your calculations.
Step 2: Multiply Each Oil's Contribution by Its HLB Value
Next, we take the amount each lipid contributes and multiply it by its HLB value:
Shea Butter: 0.20 x HLB 7 = 1.4
Jojoba Oil: 0.20 x HLB 6 = 1.2
Babassu Oil: 0.20 x HLB 7 = 1.4
Plum Oil: 0.20 x HLB 7 = 1.4
Cetearyl Alcohol: 0.20 x HLB 15.5 = 3.1
The total HLB for the lipid phase is 7.3.
Step 3: Select Emulsifiers to Match the Lipid Phase HLB
Now, let’s choose our emulsifiers. We’ve selected:
Laureth-23 (HLB 16.9)
Sorbitan Olivate (HLB 4.7)
Our goal is to create a combined emulsifier system that closely matches the total HLB of our lipid phase, which is 7.3.
Step 4: Calculate the Emulsifier Ratios
We’ll balance the emulsifiers to match the HLB 7.3 requirement. Let’s break down the math:
Laureth-23:0.25 x 16.9 = 4.22
Sorbitan Olivate:0.75 x 4.7 = 3.52
When added together, the total HLB is 7.74, which is close enough to our target of 7.3.
Step 5: Determine the Percentage of Each Emulsifier in the Formula
We’ve decided to use a total of 5% emulsifier in the formulation, to ensure stability. Now, let’s break down how much of each emulsifier to include:
Laureth-23:0.25 x 0.05 = 0.0125 (or 1.25%)
Sorbitan Olivate:0.75 x 0.05 = 0.0375 (or 3.75%)
Together, this gives us 5%, which matches our target.
The Final Formula:
Shea Butter 4%
Jojoba Oil 4%
Babassu Oil 4%
Plum Oil 4%
Cetearyl Alcohol 4%
Laureth-23 1.25%
Sorbitan Olivate 3.75%
Distilled Water 69.5%
Germaben II 1%
By carefully calculating the HLB values of our oils and emulsifiers, we’ve created a stable emulsion system that should work well within this formulation. This exercise demonstrates the importance of understanding the HLB system when working with a wide variety of emulsifiers and oils, especially for those looking to refine their formulation skills.
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