Primer paint is commonly known as primer sealer, sealer paint, oil sealer or water sealer simply because just like water-based and oil-based paints, they generally comes in two types, i.e. either oil based sealer or water based sealer (latex or acrylic primer). Sometimes on paint cans, they are also labeled as “undercoat”.

As the word ‘primer’ suggests, the primary function of a primer paint is to prime the surface of the substrate before subsequent paint layers are being applied. As primer sealer is able to penetrate into any surface irregularities and adheres to raw surfaces well, it serves to fill in any surface imperfections such as pits, holes, cracks, crevices on the walls, or existing paint that is flakey, peeling or that certain portion of the concrete that is spalling. Its main purpose is to seal up the porosity of the surface by forming an undercoat that is uniform in consistency so that when a topcoat is applied, the paint layer bonds better with the surface and is smooth and leveled.

Unlike paint, primer contains resins instead of pigments that helps in the binding of paint to the surface as well as to provide stability to the paint base. It acts as a preparatory coat to the substrate to increase the durability of any finishing paint layer applied on top of it.

Primer sealer is especially necessary for porous surfaces such as wood. Regular paint is made up of solvent, binder and colour pigment. Porous substrates tend to absorb the solvent from the paint, leaving the binder or resin no time to form a film texture on the surface, thus reducing the adhesion of the paint to the surface, affecting the durability of the paint.

Primer Paint for different substrates

Primer Paint Sealer for Wood

Wood primers comes in both solvent-based (oil-based) or water-based (latex or acrylic-based) formulas. In Singapore, painting contractors essentially carry ICI Dulux and Nippon brands of wood paint sealers. We use ICI Dulux Speed Undercoat and Nippon Aqua Primer Sealer Undercoat/ Bodelac Undercoat for timber surfaces such as wooden doors, wood furniture, stairs, handrails, etc.

Both latex and solvent-based wood sealers achieve pretty much the same results, as such either one can be used to paint regular wood surfaces like our doors. However if the doors have been painted with water-based wood sealers before, then we will advise to use water-based sealer as oil-based sealer in this case will not adhere well to a timber surface that has previously been painted with acrylic or water based sealers.

It really depends on the kind of wood surfaces you work on. For some wood furniture such as table tops that are grainy, a water-based sealer will be a better finish as it does not overpower the grains.

Another reason why some people prefer water-based wood primer sealers is because they produce lesser smell since they are of lower VOCs (volatile organic compounds), and generally dries faster before the topcoat of wood paint can be applied.

Primer Sealer Paint for Masonry

For surfaces like our walls that are made of brickwork, plastered or cement, we have got Nippon Vinilex Wall Sealers and Dulux Weathershield Acrylic/ Alkali Resisting Wall Primer Sealer.

Again these primers come in either solvent-based or water-based ones. While oil sealers have better paint-firming properties and treats chalky surfaces better, water or acrylic-based wall primers are environmental friendlier as they produce lower VOCs. Both are formulated with the main objective of improving topcoat paint adhesion.

Plastered wall surfaces are generally alkaline due to the pH level of cement, sand and lime of the mixture. Alkali can cause paint to degrade causing the paint quality to be compromised. As such, alkaline-resistant primers are essential to shield or protect the topcoat of paint from degenerating and thus, improving paint durability.

Primer Paint Sealer for Metals

Nippon Bodelac Undercoat and Dulux Eco Primer as well as Dulux Speed Undercoat are all options for priming metal surfaces, be it interior or exterior metal surfaces.

Dulux Eco Primer works on even ferrous metal works, i.e. metals containing iron compounds. Ferrous metals are usually magnetic and they include metals like cast iron, wrought iron and steel. Ferrous metals are highly corrosive and require a great amount of protective painting works to prevent them from rusting.