Acne Gel Formulation: Penetration Enhancer, Tea Tree Oil Concentration, and Packaging Compatibility

Question

I am developing an acne gel formula and have some questions regarding specific ingredients and packaging.

My formula includes Tea Tree Oil and I intended to use PE-1 Aqua as a penetration enhancer.

Can I use PE-1 Aqua in a formula without a water-oil emulsifier?
What is the appropriate concentration of Tea Tree Oil for its antibacterial effect against acne bacteria?
If using Tea Tree Oil at a high concentration, is it compatible with plastic packaging? If not, what percentage limit applies, and what types of plastic are unsuitable?

MySkinRecipes Expert · Accepted Answer

Subject: Analysis of Acne Gel Formula

Regarding the acne gel formula you provided and your questions:

Formula Analysis: The staff noted that your formula lacks a water-oil emulsifier, making PE-1 Aqua unsuitable. They recommend replacing PE-1 Aqua with Reservoir-Tech (3%) if you need a penetration enhancer.
Tea Tree Oil Concentration: The staff mentioned that research on the exact percentage of Tea Tree Oil needed for antibacterial effects against acne bacteria is conflicting. Their personal view is that using a concentration that does not irritate the skin is more beneficial, as high concentrations, even if more antibacterial, could worsen inflamed acne if they cause irritation.
Plastic Packaging: The staff advised that using Tea Tree Oil at a high concentration is not suitable for plastic packaging because it can soften the plastic over time. They cannot provide a precise percentage limit as it depends on various factors, particularly the type of plastic used.