Geogard Ultra™

What is it? Geogard Ultra™ is a natural broad-spectrum preservative manufactured and patented by Arxada (formerly Lonza). The INCI is often stated as just Gluconolactone (and) Sodium Benzoate, but if you review the data from Lonza, Calcium Gluconate is included at 1%.

From Lonza: “Geogard Ultra™ is a synergistic and patented blend comprised of gluconolactone and sodium benzoate. Aside from its proven broad spectrum activity, wide range of global regulatory approvals and broad formulation compatibility, it also contributes an added skin moisturisation benefit and has conformance with ECOCERT/COSMOS, NATRUE and the Soil Association. What makes this preservative unique is the synergy between the two ingredients which allows for its broad spectrum efficacy. Typically, organic acids on their own are too weak and often require a co-preservative or booster in order to perform optimally. The gluconolactone in this blend works in conjunction with the sodium benzoate to act as an efficient preservative booster, slowly releasing gluconic acid over time thereby contributing to the broader preservation effect.”

Read this document to learn more. It’s not the most recent version, but it’s the newest version I’ve found that’s not behind a login wall.

Geogard Ultra® is part of the Geogard® line; the “Ultra” is important as the different products within the line all have different INCIs. Other Geogard® products include Geogard® ECT, Geogard® 221, Geogard® 111S, Geogard® 111A, and Geogard® Boost PHC.

INCI Gluconolactone (and) Sodium Benzoate (and) Calcium Gluconate
Appearance Coarse white powder
Usage rate 0.75–2%
Scent Nothing noticeable in end products
Approximate Melting Point Solid at room temperature
pH range 3–6
Charge compatibility Cationic, anionic, and non-ionic compatible.
Solubility Geogard Ultra™ is soluble up to 4% in water, dispersible in glycols and alkyl sulphates.
Why do we use it in formulations? Geogard Ultra™ protects our products from microbial spoilage (bacteria, yeast, fungus). I’ve found it to be a good natural preservative option.
Do you need it? If you’ve already got Liquid Germall™ Plus you don’t need this preservative. However, if you’re looking to start working with more natural preservatives, Geogard Ultra™ is a fairly good option, though I would not call it beginner friendly due to its tendency to pH drift.
Refined or unrefined? Geogard Ultra™ only exists as a refined product.
Strengths Readily available water-soluble natural preservative with broad applications.
Weaknesses Geogard Ultra™ can cause the pH of formulations to drift downwards, so make sure you’re testing its performance and consider including a buffer in your formulation.

This is what the manufacturer recommends (copied from this source):

“To maximise the pH stability of the final formulation, it may be necessary to employ use of a sodium citrate buffer and pH adjustment as described below…

    1. Dose the final product with the required level of Geogard Ultra™ along with a 1.5x amount of sodium citrate. So, a 2% dose of Geogard Ultra™ should be accompanied by 3% sodium citrate.
    2. Mix thoroughly to ensure all solids have dissolved and adjust the pH of the formulation to 7.00–7.25 with a 30% sodium hydroxide (NaOH) solution.
    3. Finally, adjust the pH to desired final product pH (pH 5.4–5.5 is ideal) with dilute sodium hydroxide or citric acid solution.”

Due to the possibility of Sodium Benzoate and ascorbic acid (vitamin C) combining to create benzene, it is not recommended to use Geogard Ultra™ in formulations containing ascorbic acid. I have read that it should also be avoided in formulations containing citric acid, but as you can see above, the manufacturer recommends citric acid to adjust formulations made with Geogard Ultra™, so Geogard Ultra™ and citric acid are likely an ok combination.

Alternatives & Substitutions Please read this FAQ.
How to Work with It Geogard Ultra™ is not heat sensitive, so you can include it in the heated water phase of your products if desired. If cold processed it will take a while to dissolve; I will often cover my beaker with clingfilm and leave it to dissolve overnight.
Storage & Shelf Life Stored somewhere cool, dark, and dry, Geogard Ultra™ should last at least two years.
Tips, Tricks, and Quirks I find Geogard Ultra™ noticeably lowers the pH of products; I’ve created several formulations with it that I thought would need to have acid added to them but ended up needing the pH raised instead.
Recommended starter amount 30g (1.06oz)
Where to Buy it  Buy it from an online DIY ingredient supplier.

Want to learn more about preservatives and compare them? Check out this chart!

Some Formulations that Use Geogard Ultra™


Posted on

March 20, 2021