Acne was the thing I was trying to fix when I started my DIY skin care journey over 15 years ago. I spent hundreds of dollars on every oil, butter, clay, botanical, and essential oil the internet said would help. Sometimes something would help, but it never lasted for long. I was still breaking out, and when those pimples eventually did heal, they’d often leave scars.

When I finally figured out what I was doing wrong I literally had fewer breakouts overnight, existing blemishes started healing faster, and my skin was glowing. Hooray!

The big thing that my skin was missing back then was hydration, so hydrating serums like this one are now an essential part of my skincare routine. And topical hydration isn’t only good for acne! It can help boost healing, reduce irritation, plump up fine lines, and generally help your skin be happy, hydrated, and glowing.

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The history

This formulation is a #BeeBetter upgrade of the Hyaluronic Acid B5 Facial Serum formulation I shared back in 2020. I still love the original and stand by it, but I wanted to revisit it to make one “small” change. That change ended up being large enough that I thought a new post was called for so I could explain everything properly.

That one, not-so-small change? I wanted to swap the preservative from Liquid Germall™ Plus (INCI: Propylene Glycol, Diazolidinyl Urea, Iodopropynyl Butylcarbamate) to Optiphen™ Plus (INCI: Phenoxyethanol, Caprylyl Glycol, Sorbic Acid).

New American legislation in Washington state bans Diazolidinyl Urea—one of the three ingredients in Liquid Germall™ Plus. The ban doesn’t take full effect until January 1, 2027, but I suspect this will result in a slow fade for Liquid Germall™ Plus. As of this writing you can still buy it, but not from suppliers based in Washington (like Lotion Crafter).

So, I’ve been looking back at my ginormous catalogue of mostly-preserved-with Liquid Germall™ Plus formulations and thinking it’s time to update some of them—as well as explaining the how and why of those updates so you can modify your own formulations if you need (or want) to.

Why Liquid Germall™ Plus?

As a preservative, Liquid Germall™ Plus has a lot going for it:

• It is super effective at just 0.5%, so it’s pretty inexpensive + doesn’t take up much room in your formulations
• It’s effective over a broad pH range, meaning newer makers often don’t have to test the pH of their products to ensure their preservative will work (though pH testing is always a good idea!)
• Liquid Germall™ Plus is fully water soluble, so it’s easy to use in anything that contains water—no emulsifier/solubilizer/solvent required
• It doesn’t dramatically impact the pH or viscosity of our formulations
• It doesn’t alter the smell of formulations
• Liquid Germall™ Plus is compatible with all sorts of ingredients

Of course, as with all ingredients, Liquid Germall™ Plus does have downsides:

• It is heat sensitive, needing to be added below 50°C (122°F)
• It’s not natural
• It’s not available everywhere

Basically: you can use Liquid Germall™ Plus in just about anything and it will almost certainly work (as long as you use enough + your manufacturing process isn’t horribly contaminated). This makes it a great preservative for home crafters (especially newbies) because you can buy just one preservative and it’ll work in almost anything you might want to make.

As someone who shares their formulations with a wide audience of people who usually prefer to spend their formulating budget on exciting new carrier oils and vitamins rather than than half a dozen different preservatives, mostly sticking with this one super versatile and effective preservative option has been a no-brainer for years.

The original formulation

To understand where we’re starting from, let’s take a look at the original formula from 2020.

Hyaluronic Acid B5 Serum (2020)

0.1% xanthan gum (USA / Canada)
3% Propanediol 1,3 (USA / Canada)

4% sodium lactate (USA / Canada)
4% panthenol powder (vitamin B5) (USA / Canada)
0.3% allantoin (USA / Canada)
1% PEG-8 Dimethicone (USA)
0.5% Liquid Germall Plus™ (USA / Canada)

57.1% distilled water
30% low molecular weight 1% hyaluronic acid solution

On the active front, we’ve got three hydrating humectants (Propanediol 1,3, Sodium Lactate, and Hyaluronic Acid) and two skin-soothing actives (Panthenol + Allantoin). A small amount of regular xanthan gum adds a touch of viscosity and body so the serum doesn’t feel watery, PEG-8 Dimethicone reduces tackiness (a perpetual challenge with active-rich watery serums), and Liquid Germall™ Plus preserves the formulation. Distilled water acts as a solvent, hydrator, and dilutes the other ingredients to a safe & pleasant level.

The swap

There are, of course, plenty of other preservatives out there, but none that will work as a one-and-done alternative for Liquid Germall™ Plus in everything.

I think the closest options are preservatives based around phenoxyethanol, like Optiphen™ (INCI: Phenoxyethanol, Caprylyl Glycol), Optiphen™ Plus (INCI: Phenoxyethanol, Caprylyl Glycol, Sorbic Acid), and Euxyl® PE 9010 (INCI: Phenoxyethanol, Ethylhexylglycerin). Phenoxyethanol is mostly effective against gram negative bacteria, and compared to Liquid Germall™ Plus it works over an even wider pH range and is far less heat sensitive (score!). Preservatives based around phenoxyethanol are also much easier to buy around the world.

Unfortunately, phenoxyethanol is far less water soluble than Liquid Germall™ Plus, and that gets in the way of making a straight swap in almost-entirely-water formulations like this one. So, I had to make some adjustments to make sure the phenoxyethanol-based preservative mixed in rather than separated out.

Out of all the preservatives I have that include phenoxyethanol, I decided to use Optiphen™ Plus for this update as I’ve got quite a lot of experience with it and it’s pretty popular.

Optiphen™ Plus is part of Ashland’s larger “Optiphen™” line, so when you’re looking at ingredients with “Optiphen™” in the name, always check the INCI so you know exactly what it is—Plus, 200, HD, GP, OD, BSP, BSB-W, etc… or just plain “Optiphen™”. They’re all different!

In my experience, plain Optiphen™ and Optiphen™ Plus are the most common ones available to home crafters. The difference between the two is in the inclusion of 6% sorbic acid (the acid, active form of potassium sorbate) to improve performance against fungus. The sorbic acid content also pulls the pH of formulations down a bit, and I often find that useful.

Compared to Liquid Germall™ Plus, Optiphen™ Plus:

• Needs to be used at higher levels; 0.75–1.5% (vs. 0.1–0.5% for Liquid Germall™ Plus)—so we’ll need to increase the preservative percentage
• Is less water soluble, so it’ll need some help mixing into this watery formulation
• Performs best at a pH below 6 due to the sorbic acid (which is most active at pH 4.4), so we’ll need to ensure the final pH is below 6

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The adjustments

More

Based on my experience with Optiphen™ Plus and the relative simplicity of this formulation, I opted for 1% Optiphen™ Plus, reducing the distilled water to make room for it. This results in approximately 0.52% phenoxyethanol, 0.42% caprylyl glycol, and 0.06% sorbic acid in the final formulation.

Solubility

If you’ve ever tried adding Optiphen™ Plus directly to plain water, you’ll know it doesn’t mix in. You’ll get a cloudy/hazy mixture that slowly clears—but if you look closely, you’ll see the cloudy bits floating to the surface, where they form a gloppy film.

This is because two main ingredients that make up Optiphen™ Plus—phenoxyethanol and caprylyl glycol—aren’t very water soluble. Phenoxyethanol is about 0.5–2.67% water soluble (source), while caprylyl glycol is about 0.3% water soluble (source).

So, I’m turning to a trick I learned from cosmetic chemist Valerie George; we’re going to utilize phenoxyethanol and caprylyl glycol’s miscibility in propylene glycol (and propanediol 1, 3)! When speaking with Valerie at the 2024 HSCG  conference in Kansas City, she recommended pre-mixing phenoxyethanol-based preservatives with 3–5x more glycol-y solvent before adding any water.

This formulation already contained 3% propanediol 1,3; I decided to bump that up to 5% for more solvent powers.

The original formulation also included 1% PEG-8 Dimethicone; a form of silicone that’s been modified to be water soluble. I received a lot of questions about leaving it out of the 2020 version, so I experimented with that and noticed two big differences. One; the version without PEG-8 Dimethicone is tackier than the version with it. Two: the version with PEG-8 Dimethicone is clear, while the version without is hazy. The clarity of the version with the PEG-8 Dimethicone shows it is helping further solubilize the Optiphen™ Plus into the serum.

A quick note on PEG’s and phenoxyethanol; phenoxyethanol is deactivated by highly ethoxylated ingredients, and “PEG” indicates ethoxylation. So, is the inclusion of PEG-8 Dimethicone in this formulation a problem? Not in this case. It’s extremely common to find phenoxyethanol preservatives in commercial products that contain ethoxylated ingredients like polysorbate 20, PEG-100 Stearate, and Ceteareth-20. Sample formulations from companies that make phenoxyethanol-based preservatives also frequently include ethoxylated solubilizers and emulsifiers. Where you start to see supplementary preservative systems alongside phenoxyethanol is in products like shampoos that include high levels of ethoxylated foaming surfactants, like Sodium Laureth Sulfate (SLeS) (but not always!). So, ethoxylated ingredients + phenoxyethanol isn’t a hard “no”—the concentration of ethoxylated ingredients matters a lot, and 1% is fine.

pH

Optiphen™ Plus performs best at a pH below 6 thanks to the sorbic acid. To help lower the pH a bit, I decreased sodium lactate from 4% to 3% because sodium lactate pulls the pH of our formulations up. When made as written, the pH of the serum naturally falls into the 5.1–5.5 range without any additional adjusting, and that’s great.

Xanthan

This is a small and totally optional swap; I traded 0.1% regular xanthan gum for 0.2% soft xanthan gum. Soft (and clear) xanthan gums have much nicer consistencies than regular xanthan gum, and create clear products rather than hazy ones. I have found they don’t thicken as much as regular xanthan, so that’s why I doubled the amount.

You can absolutely still use 0.1% regular xanthan gum if that’s what you have; the amount is low enough that its less awesome skin feel isn’t a big deal (especially with the PEG-8 Dimethicone).

Method

I switched up the method a wee bit to ensure the Optiphen™ Plus mixes in. Our pre-distribution phase is now propanediol + Optiphen™ Plus, then PEG-8 Dimethicone and soft xanthan gum.

After that, we add everything else, stir to combine, cover, leave the xanthan gum to hydrate, check the pH, and package it up. That’s it!

Relevant links & further reading

• Propanediol 1,3 in the Humblebee & Me Encyclopedia
• Optiphen™ Plus in the Humblebee & Me Encyclopedia
• PEG-8 Dimethicone in the Humblebee & Me Encyclopedia
• Xanthan Gum in the Humblebee & Me Encyclopedia
• Hyaluronic Acid in the Humblebee & Me Encyclopedia
• Sodium Lactate in the Humblebee & Me Encyclopedia
• Panthenol (Vitamin B5) in the Humblebee & Me Encyclopedia
• Allantoin in the Humblebee & Me Encyclopedia
• Distilled water in the Humblebee & Me Encyclopedia
• More on hyaluronic acid:
  • How to start formulating with hyaluronic acid
  • Let’s Talk About Hyaluronic Acid
• How long will ______ last? What is its shelf life? in the Humblebee & Me FAQ
• Can I use a different preservative than the one you’ve used? in the Humblebee & Me FAQ
• pH
  • pH meter in the Humblebee & Me Encyclopedia
  • pH measurement in cosmetic lab: why we dilute samples? from Skin Chakra
  • How to adjust the pH of your cosmetic products from Skin Chakra
  • Why do you create a 10% dilution of a formulation before measuring the pH? in the Humblebee & Me FAQ

Soothing & Hydrating Hyaluronic Acid Serum

10g | 5% Propanediol 1,3 (USA / Canada)
2g | 1% Optiphen™ Plus (USA / Canada)

2g | 1% PEG-8 Dimethicone (USA)
0.4g | 0.2% xanthan gum (soft) (USA / Canada)

60g | 30% low molecular weight 1% hyaluronic acid solution (USA / Canada / New Zealand) (This is NOT dry powder!)
6g | 3% sodium lactate (USA / Canada)
8g | 4% panthenol powder (vitamin B5) (USA / Canada)
0.6g | 0.3% allantoin (USA / Canada)
111g | 55.5% distilled water

Weigh the Optiphen™ Plus and propanediol into a beaker or measuring cup large enough to hold the entire batch, and stir until the mixture is uniform.

Add the PEG-8 Dimethicone and soft xanthan gum and stir; the xanthan gum will not dissolve, it’ll just break up and make the mixture look hazy. That’s ok.

Weigh in everything else, stir, cover, and leave the mixture so the xanthan gum can hydrate.

I’d aim for at least 20 minutes, but I usually leave it far longer than that—I’ll go for a dog walk, make dinner, and then remember I should really go wrap up that serum several hours later.

The last step is testing and adjusting the pH: create a 10% dilution by weighing 2g product and 18g distilled water into a small bowl or beaker and whisk to combine (wondering why we create a dilution to check the pH?). Check the pH with your pH meter. Depending on the shape of your bowl/beaker you may need to tilt it in order to fully submerge the sensor on your pH meter. The pH should fall in the 5–5.5 range. If it is lower than 4.5 you’ll want to raise it; if it’s higher than 6, you’ll want to lower it. Please read this article from Skin Chakra to learn more about pH adjusting.

Once you’ve confirmed the pH is in a good place for your skin and the preservative, package the serum. I used four 50mL (1.69fl oz) bottles with treatment pump caps from YellowBee (gifted); other options include bottles with eyedropper tops or other bottles with some sort of orifice reducer cap.

Apply this serum after cleansing and then follow up with some sort of facial lotion, cream, or oil serum. Enjoy!

Shelf Life & Storage

Because this formulation contains water, you must include a broad-spectrum preservative to ward off microbial growth. This is non-optional. With good manufacturing practice and proper preservation, this formulation should last at least a year. Even with a preservative, this project may eventually spoil as our kitchens are not sterile laboratories, so in the event you notice any change in colour, scent, or texture, chuck it out and make a fresh batch.

Substitutions

As always, be aware that making substitutions will change the final product. While these swaps won’t break the formulation, you will get a different final product than I did.

• As I’ve provided this formulation in percentages as well as grams you can easily calculate it to any size using a simple spreadsheet as I’ve explained in this post. As written in grams, this formulation will make 200g.
• To learn more about the ingredients used in this formulation, including why they’re included and what you can substitute them with, please visit the Humblebee & Me Encyclopedia. It doesn’t have everything in it yet, but there’s lots of good information there! If I have not given a specific substitution suggestion in this list please look up the ingredient in the encyclopedia before asking.
• If you’d like to replace the propanediol 1,3:
  • I’d try propylene glycol, butylene glycol, or glycerin
  • You’ll need to test the formulation to ensure the Optiphen™ Plus doesn’t separate out
• If you’re like to use a different preservative, please review this FAQ and this chart.
  • Liquid Germall™ Plus will work; use 0.5%
  • Other phenoxyethanol based preservatives like Euxyl® PE 9010 (INCI: Phenoxyethanol, Ethylhexylglycerin) and regular Optiphen™ (INCI: Phenoxyethanol, Caprylyl Glycol) are good options
• You can use soft or clear xanthan gum
• You can use regular xanthan gum, but if you do, use half as much
• If you don’t have sodium lactate, try a different humectant instead. Options include more propanediol 1,3, glycerin, butylene glycol, sorbitol, and sodium PCA. You could also replace the sodium lactate with distilled water as we’ve got lots of humectant-y goodness coming from the propanediol 1,3 and the hyaluronic acid.
• You could replace Panthenol (Vitamin B5) with Niacinamide (Vitamin B3)
• If you don’t have allantoin, you could replace it with more panthenol (Vitamin B5) or more distilled water
• To easily add some scent, try replacing 20–40% of the distilled water with a hydrosol