It is comprised of (source: Arxada):

• Benzy alcohol: 77–86%
• Salicylic acid: 8–15%
• Glycerin: 3–6%
• Sorbic acid: 1–4%

It is also sold as Preservative Eco, Mikrokill ECT, and Plantaserv M, so be sure to check the INCI on what you’re purchasing.

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

Geogard® ECT will cause the pH of your formulations to drop.

The manufacturer lists lip products as a possible application.

Can cause the pH of a formulation to drop so much that it needs to be raised.

Due to the salicylic acid content, Geogard® ECT cannot be used in products for children under 3 except for shampoo.

If you are using Geogard® ECT to preserve a formulation that contains salicylic acid as a skincare active, the salicylic acid content in the preservative will count towards the maximum allowable concentration of 2%. If we assume Geogard® ECT contains 15% salicylic acid, when used at 1%, the overall formulation will contain 0.15% salicylic acid. This leaves room for 1.85% additional salicylic acid.

Euxyl™ k 903 is comprised of (source: Formulator Sample Shop):

• Benzyl alcohol: 78–84%
• Benzoic acid: 11–13%
• Dehydroacetic acid: 6.5–7.5%

From Ashland: “Euxyl™ k 903 preservative is only limitedly soluble in water. 100g of water at 20°C dissolve 1.2g of Euxyl™ k 903 preservative. In polar solvents such as 1,2-propylene glycol, propanol or acetone, Euxyl™ k 903 preservative is readily soluble. In polyalcohols such as glycerol and sorbitol Euxyl™ k 903 preservative is moderately soluble. In aliphates with hydrophilic groups such as 2-octyldecanol and isopropyl myristate, Euxyl™ k 903 preservative is limitedly soluble. In pure aliphatic solvents it is slightly soluble.”

Euxyl™ k 903 works best in a pH range of 3–6, with 5–5.5 being recommended. This preservative is more effective at lower pH ranges. I find it lowers the pH of formulations ~0.75–1.5 pH points, depending on the formulation. This drop can often be enough to take the product into the effective range for the preservative.

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.

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 Lonza provides at least one Geogard Ultra™ sample formulation that includes citric acid for pH adjusting, so I think citric acid and Geogard Ultra™ are likely an ok combination.

The limiting ingredient in Liquid Germall™ Plus for regulatory purposes is the Iodopropynyl Butylcarbamate. The maximum usage rate of 0.5% Liquid Germall™ Plus results in 0.002% Iodopropynyl Butylcarbamate in finished formulations, which is below the maximum usage rate for leave-on and rinse off purposes in the USA, EU, and Japan. In the EU, Iodopropynyl Butylcarbamate is not to be used on children under 3 years of age unless in rinse-off products. No such restriction exists in the USA or Japan, so I’d say it’s up to you if you wish to use this preservative in leave-on products for people under 3 years.

Liquid Germall™ Plus is a patented product made by Ashland.

In addition to its versatility in terms of efficacy, it also works over a broad pH range, generally negating the need to test the pH of your end product unless you know it contains high concentrations of extremely acidic or basic ingredients. If you don’t want to invest in pH testing equipment, this is a great added bonus!

Iodopropynyl Butylcarbamate is present at 0.004% in Liquid Germall™ Plus; 0.5% usage means a finished formulation will contain 0.002% Iodopropynyl Butylcarbamate. This is well below the CIR limit of 0.1%.