Making Liquid for Sheet Masks

When formulating the liquid for soaking sheet masks, there are several points to consider that differentiate it from regular essences or serums:

Differences from Regular Essence/Serum

• Viscosity: Sheet mask liquid is typically less viscous (more watery) than regular serums or essences to allow the mask material to be fully saturated.
• Volume: A larger volume of liquid is used per application compared to the small amount of serum/essence applied directly to the skin.
• Application Time & Occlusion: Sheet masks are left on for a longer duration (typically 15-20 minutes) and create an occlusive layer, which can enhance ingredient penetration but also potentially increase irritation risk.

Considerations and Precautions

• Preservation: Due to the high water content and the application method (prolonged contact on skin), robust preservation is crucial to prevent microbial growth.
• Ingredient Concentration: While hydration is key, potent active ingredients might be used at lower concentrations than in a leave-on serum to minimize the risk of irritation during the extended contact time under occlusion.
• Ingredient Choice: Avoid ingredients known to be highly irritating or sensitizing, especially under occlusion. Focus on soothing, hydrating, and barrier-supporting ingredients.
• pH Level: Ensure the pH is skin-compatible to avoid irritation.
• Stability: The formulation must be stable over time, considering the packaging and storage conditions.

Why Some Masks Require Rinsing Off

Some sheet masks recommend rinsing after use for several reasons:

• Residue: To remove any sticky, heavy, or uncomfortable residue left on the skin by the formulation.
• Ingredient Type/Concentration: Masks containing high concentrations of certain ingredients (like strong acids or certain polymers) might be designed for temporary contact rather than leave-on to prevent potential irritation or build-up.
• Formulation Design: The overall formulation might be intended as a treatment step followed by the rest of a skincare routine, and rinsing is part of that process.

In summary, while sharing many similarities with essences/serums, sheet mask liquid requires careful consideration regarding preservation, ingredient concentration under occlusion, and overall formulation aesthetics and safety for prolonged skin contact.