After choosing the perfect paint shade for your room, it can be tempting to start rolling that paint immediately. Before you do, it’s important you ask yourself—should you use a primer for walls before painting? We’ve been experts in making and using paints in Australia since our inception in 1935, so you can trust that we know what we’re talking about in this primer guide.

What is an Undercoat or Primer?

An undercoat, primer, or prepcoat are all words for the preparatory layer applied to a surface before the topcoat of paint. This undercoat acts as a foundation, providing a smooth and consistent surface for the topcoat to adhere to. Unlike the topcoat, which adds colour and aesthetics, the undercoat's primary function is to enhance adhesion and coverage, ensuring a more durable and attractive finish.

Do You Need to Undercoat Already Painted Walls?

The need for an undercoat or primer varies depending on your project. If you're freshening up a wall with a similar colour and the surface is in good shape, you may be able to skip the primer. There are 6 key factors to consider that affect when you need to use primer:

1. Surface or Substrate Type: An undercoat is vital for fresh, unpainted surfaces like new drywall or wood. These surfaces are porous; without an undercoat, they'll absorb the topcoat unevenly. Specific materials like wood, metal, or plaster also benefit from an undercoat to prep for the final layer.
2. Colour Changes: Switching from dark to light colours—or the reverse—is tricky. An undercoat prevents the old colour from tainting the new, ensuring you get the shade you want.
3. Paint Compatibility: Oil-based and acrylic paints generally don't mix well. An undercoat acts as a go-between, preventing issues like peeling or poor adhesion.
4. Wall Condition: For walls with minor imperfections like small cracks or rough patches, an undercoat helps even things out. However, It’s important to note that an undercoat is not a “filler”.  For walls with larger cracks, holes or rough surfaces - these will need to be filled with a suitable non-silicone gap filler first.  Once the gap filler has cured for the recommended time, the undercoat can then be applied over the wall and filled in areas.
5. Stains and Marks: Got stubborn stains or marks? An undercoat stops them from seeping through your topcoat, especially important for issues like watermarks or smoke residue.
6. Sheen Transition: If you're going from a high-sheen paint, like gloss, to a softer one, like satin, an undercoat helps ensure even coverage and proper adherence to the old glossy surface.

Choosing the Right Primer

Now that you know why you need primer, choosing the right undercoat can feel overwhelming with so many options available. Regardless of your project, we have a variety of prep coats to suit different needs:

Ultra Premium Range

Prepcoat Ultracover

• Uses: Interior/Exterior
• Key Features: Multi-use, stain sealer, excellent gloss holdout, undercoats almost anything.
• Best For: Versatile projects that require a primer, sealer, and undercoat all in one.

Prepcoat Ultraseal

• Uses: Interior/Exterior (Plaster or Timber)
• Key Features: Great for sanding & coverage, superior coverage, compatible with both water-based and oil-based paints.
• Best For: Projects that need a premium quality sealer undercoat for various paint types.

Prepcoat Ultralock

• Uses: Interior/Exterior
• Key Features: Rapid drying, turps-based, superb adhesion, stain sealing.
• Best For: Jobs requiring quick turnarounds and high adhesion.

Prepcoat Ultrahold

• Uses: Interior/Exterior
• Key Features: Methylated spirit-based, blocks stains and odours.
• Best For: Areas plagued by stubborn stains or unpleasant odours such as water-damaged or tobacco-stained walls.

Prepcoat Ultraprime

• Uses: Interior/Exterior
• Key Features: Anti-corrosive, suitable for water or solvent-based topcoats.
• Best For: Metal surfaces requiring rust protection.

Elite Range

Tricoat Primer Sealer Undercoat

• Uses: Interior/Exterior
• Key Features: 3-in-1, low odour, excellent gloss holdout, brilliant adhesion.
• Best For: Various surfaces requiring a multi-purpose product.

Acrylic Sealer Undercoat

• Uses: Interior/Exterior
• Key Features: Low odour, over 99% VOC free, easy to sand, quick drying.
• Best For: Eco-conscious projects.

General Purpose Undercoat

• Uses: Interior
• Key Features: Turps-based, self-levelling, high opacity.
• Best For: Pre-painted surfaces requiring superior coverage.

Quick Dry Primer Undercoat

• Uses: Interior/Exterior
• Key Features: Fast drying, superb filling, tannin blocking resistance.
• Best For: Quick projects requiring excellent filling and sanding properties.

NewLife Range

NewLife Sealer Undercoat

• Uses: Interior
• Key Features: Water-based, premium quality, designed for topcoat preparation.
• Best For: Interior projects requiring a strong foundation for the finishing layer.

Specialist Products

Industrial Primer

• Uses: Industrial
• Key Features: Quick-drying, anticorrosive, suitable for iron and steel.
• Best For: Industrial settings requiring corrosion protection.

Industrial Zincalene

• Uses: Industrial
• Key Features: Epoxy-based, high zinc content, superior corrosion protection.
• Best For: Long-term protection of steelwork in industrial applications.

Prime Your Paint Project For Success

Priming is not a step to be overlooked, regardless of your project's size. Proper preparation, including priming, sets the stage for a superior, long-lasting paint job.

If you're unsure which primer to use, speak to our experienced team for tailored advice or view our collection of paint preparation products below.