Information Regarding Your Questions

Thank you for your questions. Here is the information based on the product details available:

1. Custom Mixing Service

Information regarding a service where the shop mixes formulas based on selected raw materials is not available from the product details I can access.

2. Differences Between Vitamin C Products

Based on the product descriptions, here are the differences between the Vitamin C products you mentioned:

• Vitamin C (L-ascorbic acid) (Ultra-Fine) (Product ID 133): This is L-Ascorbic Acid in an ultra-fine powder form. L-Ascorbic Acid is considered the most effective form of Vitamin C for skin benefits. However, this form has low stability, especially when dissolved in water, and requires careful formulation (e.g., in anhydrous formulas) to remain effective. It is a raw material.
• Vitamin C E Ferulic (Product ID 70): This product uses L-Ascorbic Acid as the main component and is formulated with Vitamin E and Ferulic Acid to help stabilize the L-Ascorbic Acid, making it more stable than L-Ascorbic Acid alone. It is presented as a kit or technology to create a stable Vitamin C formulation.
• Stabilized Vitamin C (Natural-C Glycol™) Serum (Product ID 486): This is a ready-made liquid base containing 15% L-Ascorbic Acid. It is described as highly stable and ready for use as a finished product. It is explicitly stated that it is not suitable for mixing additional ingredients as this may affect its stability.

Which is more effective? L-Ascorbic Acid is generally considered the most effective form of Vitamin C. The stability of the final product is crucial for effectiveness. While L-Ascorbic Acid powder (Ultra-Fine) is the raw, potent form, its low stability makes it challenging to work with. Both Vitamin C E Ferulic and Stabilized Vitamin C (Natural-C Glycol™) Serum are designed to provide L-Ascorbic Acid in a more stable format, aiming for better delivery and sustained effectiveness compared to unstable L-Ascorbic Acid formulations. Stabilized Vitamin C (Natural-C Glycol™) Serum is presented as a highly stable, ready-to-use base with a guaranteed 15% L-Ascorbic Acid content.

3. VitC MAP (Referring to Vitamin C L-Ascorbic Acid Ultra Fine)

Based on the product description for Vitamin C (L-ascorbic acid) (Ultra-Fine) (Product ID 133), this product is L-Ascorbic Acid powder, which is a raw material, not a finished product. The description also mentions Magnesium Ascorbyl Phosphate (MAP) as a different type of Vitamin C sold by the company; the product linked is specifically L-Ascorbic Acid Ultra-Fine.

3.1 Adding Ingredients to VitC MAP (L-Ascorbic Acid Ultra Fine)

Since Vitamin C (L-ascorbic acid) (Ultra-Fine) (Product ID 133) is a raw material powder, it is not a finished product to which ingredients would be added by the shop. It is intended for use in formulations. As mentioned in point 1, information about the shop providing custom mixing services is not available.

4. BHA Salicylic Acid

Salicylic Acid (BHA) (Product ID 148) is a high-purity (>99.9%) raw material in powder form. It is not a finished product. The percentage of Salicylic Acid in a final cosmetic product depends on the formulation and intended use, subject to FDA regulations (e.g., typically not exceeding 2% for leave-on skin products).

Regarding adding Vitamin B3, B5, and having the shop mix it, as stated previously, information about the shop providing custom mixing services for raw materials or finished products is not available.