Preservatives: Imidiazolidinyl and diazolidinyl urea

Imidiazolidinyl urea is one of the most common preservatives, found as Germall 115 (a powder). Created through a chemical reaction of allantoin and formaldehyde in the presence of a sodium hydroxide solution, it's then neutralized with hydrochloric acid and evaporated.

It's a good anti-bacterial preservative that isn't great with fungus, so it is generally combined with other preservatives that fight fungus better, like the parabens. In fact, using imidiazolidinyl urea with parabens potentiates or increases the effect of both preservatives! With a pH of 4 to 9, it's appropriate for pretty much any product we make, except for completely anhydrous products as it isn't soluble in oils. It's not heat stable, so it must be added to the cool down phase of our products.

Imidiazolidinyl urea is approved at up to 0.6% in the EU and 0.3% in Japan.

Diazolidinyl urea is a relative of imidiazolidinyl urea (found as Germall II) and is created in the same way with allantoin as a starting point. It is water soluble with low oil solubility, and is also a good anti-bacterial but weak fungal preservative, so it must also be combined with another preservative for broad spectrum protection. Its pH is also 4 to 9, so it's compatible with just about any product we make (except for anhydrous products as it's not oil soluble), and it should be added to the cool down phase of our products because it's not heat stable.

For a PDF on the toxicity of imidiazolidinyl urea, please click here.

Both ureas are considered low formaldehyde releasers. Diazolidinyl urea can be found in Liquid Germall Plus and Germaben II.