# The difference between a bonding primer and shellac primer

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We are discussing two different chemistries, and they behave differently in the field.

A bonding primer is designed to adhere to surfaces that typically don’t accept paint—factory finishes, lacquer, varnish, laminate, PVC, metals, and other low-surface-energy materials. Its strength is flexible adhesion. A good bonding primer will move with the substrate without letting go. That matters because cabinet doors, trim, and doors expand, contract, and flex. Bonding primers are built for that kind of movement.

A shellac primer is something entirely different. Shellac is one of the oldest coating technologies still in use. It dries fast and blocks stains extremely well, but the film it creates is hard and brittle. Shellac doesn’t flex, it doesn’t tolerate heat, and it doesn’t like moisture. It also dissolves instantly in ammonia and weakens over time in warm, humid environments. That’s why shellac primers fail on kitchen cabinets: the environment exposes every weakness the chemistry has.

So when do you use each?

Use a bonding primer when the priority is long-term adhesion to a slick, stubborn, fully finished surface—doors, cabinets, trim, vanities, and anything factory-coated. Use it when the coating is exposed to daily handling, heat, humidity, or cleaning. Cabinet work, especially, calls for a primer that can move without fracturing the film beneath the paint.

Use a shellac primer when you need to lock in a stain, seal knots, block odors, or address a problematic surface that requires containment rather than flexibility. Shellac is a sealant, not a structural foundation. It gives you speed, not durability.

More on [Why shellac primers don’t belong on kitchen cabinets](https://jackpauhl.gitbook.io/archive/field-notes/product-knowledge/why-shellac-primers-dont-belong-on-kitchen-cabinets)