As a distinguished figure in the realm of clean beauty and skincare, I can provide you with guidance on the application of peptide serum and niacinamide. Both peptide serums and niacinamide offer unique benefits to the skin, and their order of application can influence their efficacy.

In general, it is recommended to apply niacinamide before peptide serums. Niacinamide is a water-soluble vitamin (vitamin B3) that is known for its ability to improve the skin's barrier function, reduce inflammation, regulate sebum production, and minimize the appearance of pores. It is also known to enhance the synthesis of ceramides, which are essential for maintaining the skin's moisture barrier.

On the other hand, peptide serums contain peptides, which are amino acid chains that can stimulate collagen production, improve skin elasticity, and reduce the appearance of fine lines and wrinkles. Peptides are typically larger molecules and may have difficulty penetrating the skin if applied over a product with a smaller molecular size, such as niacinamide.

To maximize the benefits of both products, it is generally recommended to apply niacinamide first, allowing it to fully absorb into the skin. After a few minutes, you can then follow with your peptide serum. This order allows the niacinamide to work on improving the skin's barrier function and overall health before the peptides are applied to target specific concerns like collagen production.

However, it's important to note that skincare routines can vary depending on individual preferences and the specific products being used. If you find that applying the peptide serum before niacinamide works better for your skin, you can certainly experiment with different application orders and observe how your skin responds.