Hi
Think of it as a sandwich....nail plate....primer....product.
Methacrylic acid, commonly known as acid primer, creates a hydrogen bond between the nail plate and the primer and a covalent bond between the primer and the product.
Non-acid primer creates a covalent bond between the nail plate and the primer and a covalent bond between the primer and the product.
A covalent bond is a stronger bond than a hydrogen bond, to break down under every day circumstances, ie knocks, water, wear and tear etc, a hydrogen bond is more easily broken down, however, in nail services I have never really had any problems with using acid primer and a hydrogen bond.
Some products do not require primer at all and create a covalent (strongest) bond between the nail plate and the product.
Both are safe to use when used professionally and as instructed in your training.
Hope this makes sense xxx
Addage from the articles section
http://www.salongeek.com/general-articles/2699-primer-lifting.html