Answer to Your Formulation Questions

Based on the information from the discussion and product details, here are the answers to your questions:

1. Cause of the cream becoming liquid: The reason your cream became liquid immediately after adding Eye Preserved is primarily due to the incompatibility between Eye Preserved and the thickeners you used, Pro Polymer and Light Cream Maker. Eye Preserved (Polyhexamethylene Biguanide, PHMB) is a cationic ingredient, while Pro Polymer and Light Cream Maker are anionic polymers. When mixed, these opposite charges interact, causing the polymer structure that provides thickness to break down, resulting in the cream becoming thinner. This is a normal reaction due to this specific incompatibility, not a sign of something going wrong or producing harmful substances.

2. Effectiveness of active ingredients: The change in the cream's texture does not affect the efficacy of the active ingredients in your formula. They should still retain their intended benefits.

3. Safety of the liquid cream: Yes, the cream is safe to use even in its liquid state. The reaction between Eye Preserved and the thickeners does not create any toxic or harmful substances. You can safely use the cream without concern for adverse health effects. As you observed, experiencing no irritation after using it confirms its safety for your skin.

4. Syringe storage: The syringes provided are made from materials like Polypropylene and Polyethylene, not natural rubber, which are compatible with the ingredients and do not react chemically with them over time. The slightly oily residue you might see in some syringes is a safe lubricant applied during manufacturing to ensure smooth plunger movement; it is not expected to cause skin issues or allergies. The red stoppers are also made of compatible material, although they are designed for temporary sealing and can be physically damaged by excessive force, not chemical reaction from the contents like OMC or octisalate (though these can dissolve ink on the syringe scale, they don't react with the plastic/stopper material itself).

To achieve your desired cream consistency in future formulations using Eye Preserved, the recommended method is to add Light Cream Maker in stages. Add the initial amount to create the base cream, then incorporate Eye Preserved. If the cream thins, gradually add more Light Cream Maker while stirring until the desired thickness is achieved again.