Adding Ingredients to Ready-to-Use Vitamin C Serum Kit

Regarding adding Phenylethyl Resorcinol and Ergothioneine to the ready-to-use Vitamin C E Ferulic kit, ready-to-use formulations are typically complete and stable as is. Adding raw ingredients like Phenylethyl Resorcinol and Ergothioneine may disrupt the stability, pH, or overall efficacy of the kit. Therefore, it is generally not recommended to add raw materials to a ready-to-use product unless the product description specifically states that it is possible. If you wish to use these ingredients together, it would be better to create a new formulation from scratch or use the products separately.