Adding Penetration Enhancer and Flaking Issue in Homemade Skincare Formulas for Dry, Sensitive Skin

Ethoxydiglycol for Penetration

Adding Ethoxydiglycol can indeed help enhance the penetration of active ingredients into the skin. However, the recommended usage rate for Ethoxydiglycol in leave-on cosmetic products is currently limited to not more than 2.6%. Using it at 5% in your Essence, Serum, Eye Cream, and Face Cream formulas would exceed this regulatory limit for leave-on products.

While 5% might offer significant penetration enhancement, it is advisable to adhere to the recommended maximum usage rate, especially given your very sensitive skin. Using a concentration higher than recommended could potentially increase the risk of irritation.

Therefore, adding Ethoxydiglycol at 5% is not recommended for your leave-on products. You could consider adding it at a lower concentration, such as 1-2%, which can still provide some level of enhanced penetration while staying within recommended guidelines and potentially being gentler on your sensitive skin.

Flaking Skin Issue

You mentioned experiencing flaking or peeling after using your four formulas overnight, despite the skin feeling moisturized initially. This is a common issue that can occur with certain ingredient combinations or concentrations, particularly on dry and sensitive skin.

There are a couple of potential factors in your formulas that could be contributing to this flaking:

1. Willow Bark Extract (Natural Salicylic Acid): Your Serum formula contains 10% Willow Bark Extract. Willow Bark Extract contains natural salicylic acid, which is an exfoliant. At a 10% concentration, it provides an exfoliating effect roughly equivalent to 1.8-2.0% synthetic Salicylic Acid. While exfoliation can help with skin renewal, using a product with this level of exfoliant overnight, especially layered with other products, might be too aggressive for your very dry and sensitive skin. Exfoliants can sometimes disrupt the skin barrier, leading to increased moisture loss and visible flaking as the skin sheds cells.
2. High Concentration of Humectants: Your Essence and Serum contain multiple humectants like Hyaluronic Acid (Standard and Nano), Water Lock, Moist 72, and Natto Gum. While these ingredients are excellent for attracting and holding moisture, applying multiple layers with high concentrations of humectants, particularly in a dry environment (like an air-conditioned room overnight), can sometimes lead to a phenomenon where moisture is drawn from the deeper layers of the skin and then evaporates from the surface, potentially causing a feeling of dryness or flaking. This is less likely the primary cause than the exfoliant, but it can be a contributing factor if the skin barrier is compromised.

Given your skin type (dry, dehydrated, very sensitive), the exfoliating action of the Willow Bark Extract in the Serum is the most probable cause of the flaking. Your skin barrier might be reacting to the exfoliation by becoming dry and peeling.

Recommendations to address flaking:

• Reduce or Adjust Serum Usage: Consider reducing the frequency of using the Serum containing Willow Bark Extract. You might use it only a few nights a week instead of every night. Alternatively, you could try reducing the concentration of Willow Bark Extract in the Serum formula.
• Assess Hyaluronic Acid Concentration: While the Hyaluronic Acid concentrations in your individual formulas (0.6% in Essence, 0.3% in Serum) are within or slightly above the typical recommended range for very dry skin (0.3-0.5% total HA), the cumulative effect of layering might be a factor. However, addressing the exfoliant is likely the priority.
• Support the Skin Barrier: Ensure your routine adequately supports your skin barrier, especially after using any exfoliating product. Your Face Cream contains beneficial ingredients like Ceramide Complex and Squalane, which help strengthen the skin barrier and prevent moisture loss. Make sure you are applying this consistently.
• Simplify the Routine: On nights when your skin feels particularly sensitive or dry, you might consider simplifying your routine and focusing on gentle, hydrating, and barrier-repairing products, perhaps skipping the Serum with Willow Bark Extract.

In summary, while 5% Ethoxydiglycol is likely effective for penetration, it exceeds the recommended usage limit for leave-on products. The flaking is most likely caused by the exfoliating effect of the 10% Willow Bark Extract in your Serum, potentially exacerbated by the layering of multiple humectant-rich products on sensitive skin. Adjusting the use of the Serum is recommended.