Difference between primer and base coat? Is there an impact on the durabilty of the coating?

Primer or Base Coat? We explain the difference and what you have to consider for a successful coating.

Both terms are often used for pure bonding bridges and base coats. 

Primer and base coat fulfill different tasks. They are often substantialy different and not comparable in the application.

The adhesion of a coating is the result of a intermolecular connection between surface and coating material.

Adhesion depends on

  • Chemical properties
  • Surface quality and composition
  • Surface condition (Roughness, smoothness, porosity)

Example:  The adhesive tensile strength of an Epoxy resin on matted glass (sandblasted) is 5 times better  compared with a sample applied on a smooth non treated glass surface.  

Primer increase the adhesion on critical surfaces. In many cases the right primer allows a safe and durable connection between coating/glue and surface.

Ideally the primer works as chemical coupler which brings enourmous strength between surface and coating. Such primers are usually no binding agents and the won´t create a film!

Ideally the effect of a primer / bonding bridge is based on a double function. 1. reaction with the surface. 2. reaction with the coating material itself.

Example: Epoxy functional Silan primer could increase the adhesion of Epoxy resin on a  smooth (not sandblasted) surface more than 10

  • Special Primer  A-867 for coatings made of PUR and EP resins
  • Special primer G-868 for coatings made PMMA and EP resins.

Base Coats have other tasks. They are called deep ground or primer (which is irritating because Primers have other functions) Base coats are adjusted to the surface

  • surface strengthen and hardening
  • bond fine dust at the surface
  • pore filling, block out and isolate humidity, pollutants etc.

Base coats are similar to the following coatings. They are low viscous without or less fillers and pigments.  

Pore filling and closing is the important task of base coats. A sufficient pore filling avoids trouble with the final coating. Pores which aren´t filled properly produce Pinholes in the fresh coating. Pinholes are created by air, trapped inside the holes meanwhile coating. The air pops up and disrupts the fresh coating film.

Without base coat the bindig agent of the final coating gets „filtered“. The result is a damaged coating. This arises when

  • the surface is covered with pores
  • the surface sucks
  • no base coat is used
  • the base coat was used insufficient

These incidents create in the border area between coating and surface a lack of binding agent ( because it gets sucked away – and is no longer available for a proper coating). The result: Adhesion problems! Proper formulated coatings avoid this problem.

Our Epoxy Coatings for balcony, access balcony, garages, storage rooms, industrial floors Silox EPW 857  is available in many different colours and easy to apply. The surface is easy to clean and abrasion resistant. The suitable base coat is Silox EPW 856.

For more information contact our Team in Germany!

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