Burning/Stinging Sensation from Formula

The burning or stinging sensation you experienced when first applying the formula is likely due to the high concentration of DMAE (SkinTight MD™) at 20%. According to the product information for DMAE, using concentrations above 5% may cause skin irritation, especially on thin or sensitive skin. The recommended usage rate is typically 1-10%, with 3% being recommended.

While Phenoxyethanol can also potentially cause irritation in some individuals, particularly at higher concentrations or on sensitive skin, the 1% concentration in your formula, especially using the Extra Pure grade, is generally less likely to cause the strong initial burning sensation compared to the 20% DMAE.

It is good that you did not experience a rash, but the burning sensation indicates that your skin is reacting to the formula, most likely due to the high level of DMAE.

Regarding making a small batch without a preservative: Yes, as suggested by another user, you can make a small amount that you plan to use within about a week. It is crucial to store this batch in the refrigerator and ensure all your equipment and containers are thoroughly cleaned and sanitized (using alcohol spray, for example) before mixing to minimize bacterial contamination. This approach avoids the need for a preservative for short-term use.

If you wish to make a larger batch for longer storage, or if the burning sensation from the high DMAE concentration is too uncomfortable even for short-term use, you might consider reducing the concentration of DMAE in the formula or trying a different, milder preservative like Eye-Preserved or Mild-Preserved as suggested by another user.