When painting a completely bare surface, you'll need a quality primer coat to get the best finish. Cromwell stock a large range for primers suitable for a variety of surfaces including wood, metal and concrete. With big brands like Action Can, EverBuild, Rustoleum and Hammerite, you'll be sure to find something in the range to suit your needs.

What are primers?

Primers are the first coat of paint you will need when painting a previously unpainted surface. Primers work by creating a base layer for additional coats to bond to creating a much more professional and durable finish.

Why primers?

When painting a completely bare surface, a topcoat alone will result in an uneven finish, this is because the surface absorbs the paint, which may also result in you needing to apply more paint than necessary. In some surfaces particularly metals primers are a good way to protect against issues like rust as they create a seal between the surface of the metal and the environment, with some specialist primers containing rust resistant properties. These are particularly useful when painting outdoor metal surfaces like railings, as these are constantly exposed to the elements.

Types of primers

There are various types of primers that are suitable for a range of different applications, there are also different application methods to consider. To help get a better understanding of primers, as well as some of their applied uses, the most common types are listed below.

• Oil based - Probably the most commonly used type of primer. Oil based primers work well on multiple surfaces, including both interior walls and wood. They are also great if you plan to use enamel paint as a topcoat. They are perhaps the best choice for wooden surfaces as wood is porous and the oil base acts as a seal.

• Latex based - Latex based primers are a good choice if you're painting in an enclosed space as they are known for having low or no harmful fume release. It has a highly versatile application range and can be used on surfaces ranging from drywall, soft woods, concrete and galvanised metals. It has the added advantage of being both durable and fast-drying, it is also easier to clean as it is water soluble. Its only real drawback comes when trying to cover up dark stains, it is also not recommended for hard woods and ungalvanized metals.

• Shellac based - Shellac based primers have excellent coverage and sealing properties as well, as working well to block staining. It produces great results on wood, metal and plaster with excellent adhesion. The drawback to shellac primers is that they can only really be used indoors, and this can be a problem if working in poorly ventilated areas as they produce fumes. They can also be really stubborn to clean from painting equipment (that excellent adhesion to surfaces includes brushes and rollers.)

• Specialist metal primers - Primers for metal surfaces often include the addition of rust protection. Industrial metal primers act as a galvanising layer, helping seal the surface and protecting against the degrading effects of rust and corrosion. As a result they work especially well on outdoor metal surfaces like railings.

Considerations when choosing a primer

There are a few key considerations when choosing a primer. You can find the most common ones below.

• The surface being painted - Not all primers work well on all surfaces. Oil and latex tend to be the most versatile but have their limitations. More specialist primers like shellac and metal primers are suited to few applications although they produce excellent results within that scope. Before selecting a primer it is best to check whether it is recommended for the surface you wish to paint.

• The application method - To get an even surface/total coverage of the surfaces you wish to paint might require more tools than just a paintbrush and a roller. It might be time consuming and hard to achieve the desired finish with these tools alone, in these cases an aerosol based paint or a spray delivery system might yield better results.


Is primer paint waterproof?

As no paint is waterproof this also applies to primers, whilst paints can form a protective seal on a surface, they can't totally eradicate moisture from reaching the surface.
Can primer be used as an undercoat?

Primers and undercoats perform different roles. A primer is used as a base layer for additional coats to stick to where as an undercoat is designed to create a level base for a topcoat.