A primer will also increase the practicality and longevity of your finish as it ensures proper adhesion of the paint to the substrate/surface. Some primers are even specifically made to ensure adhesion of coatings on specified substrates, such as ROCKCOTE MgO Board Primer.
The use of primers on large broad wall areas also reduces the possible inconsistencies in the finish that can be particularly noticeable on large surface areas in certain lighting conditions.
Choosing a Primer
There are a couple of key points you need to keep in mind when choosing a primer:
• What are you painting (what is your substrate)?
• What product are you using over the primer?
The project substrate will have the greatest impact on which primer is required to provide optimum adhesion and longevity. If you are starting from a bare substrate, you will need to use a primer that provides the best adhesion of the final coats to that substrate (refer to the ROCKCOTE Systems Guide for a primer suitable for your application). If you are painting over another product, such as a previously painted substrate or render, you will also need to choose the primer that provides the correct adhesion over these surfaces.
The product that you are using over the primer will also have an impact on which primer is suitable. For example, if you are intending to render over the primer (i.e. with a Coloured Render), the primer needs to have grit, such as ROCKCOTE Texprime, to enable the render to ‘grab’ onto the primer and not slip. However, if you are intending to paint over the primer, you will need a non-textured primer, such as ROCKCOTE Masonry Primer, to ensure a smooth, consistent paint finish.