Which type of primer is not based on acid?

The type of primer that is not based on acid is indeed categorized under non-acid and acid-free primers. Non-acid primers are formulated without acidic components, making them a gentler option for clients with sensitive skin and reducing the risk of damage to the natural nail. These primers create a strong bond without the use of corrosive acids that can lead to irritation or other negative reactions.

Acid-free primers, on the other hand, are specifically designed to provide adhesion without acidic ingredients and are suitable for a wide variety of gel and acrylic systems. Both non-acid and acid-free primers aim to enhance bonding while minimizing risks associated with acid use.

In this context, the correct answer encompasses all types of primers that do not utilize acid in their formulation, which includes both non-acid and acid-free primers. This understanding is critical in providing safe nail services that cater to the diverse needs of clients and ensuring optimal nail enhancements.