Is Primer Really Necessary Before Painting?

November 21, 2025
When starting any painting project, one of the most common questions homeowners ask is: “Do I really need primer before I paint?” While it may feel like an optional extra step, primer is often the key to achieving a smooth, durable, long-lasting finish. In many cases, skipping it leads to patchy colour, peeling paint, uneven coverage, or stains bleeding through your new topcoat.

Here’s everything you need to know about when to use primer, why it matters, and how the right prep can completely transform your results.
primer painting perth

What Is Primer and Why Is It Important?

Primer is a specially formulated undercoat designed to prepare surfaces for paint. Its job is to create a stable, uniform base that helps the topcoat adhere properly. Think of it as the glue between your wall and your final paint layer. 

Using primer correctly makes your paint job:
  • Stick better
  • Cover more evenly
  • Last longer without peeling
  • Resist stains and moisture
  • Look smoother and more professional
Skipping primer may seem faster, but it often costs more in the long run because you need extra coats, touch-ups, or full repainting sooner than expected.

Do I Need Primer Every Time I Paint?

Not always - but in many situations, primer is essential for a high-quality, lasting result.

Here are the key times when primer is absolutely necessary:

When Painting Over Dark or Strong Colours

If you’re covering a deep red, navy, charcoal, or any bold colour, primer ensures the new colour looks clean and even.

Without it, the darker shade can show through for several coats - wasting time and paint.

When Painting New Plaster, Gyprock, or Bare Surfaces

Fresh surfaces are porous and absorb paint unevenly.

A good primer:
  • seals the wall
  • stops patchiness
  • helps your topcoat glide on smoothly
This applies to bare timber, fresh plaster, new drywall, and unpainted masonry.

When Painting Over Stains or Water Marks

Primer blocks stains from bleeding through your new paint.

This is particularly important for:
  • water stains
  • smoke stains
  • grease marks
  • crayons or heavy scuffs
A stain-blocking primer prevents frustrating patches appearing later.

When Switching Paint Types (e.g., Oil-Based to Water-Based)

If you’re applying a water-based paint over old oil-based paint, primer is a must.

It helps the new paint grip properly and prevents peeling.

When Walls Are Glossy or Have Been Previously Enamel Painted

Glossy surfaces don’t hold paint well.

Primer along with light sanding creates a surface the new paint can bond to.

When Painting Exterior Surfaces Exposed to Harsh Weather

Exterior walls face moisture, UV damage, wind, and temperature changes.
 
Primer improves adhesion and boosts the lifespan of your exterior paint job.

Benefits of Using Primer: Why It’s Worth It

Here are the biggest benefits homeowners notice when they use primer:
  • Better Adhesion: Primer helps paint stick securely, preventing future peeling or flaking.
  • Fewer Coats Needed: Because primer blocks old colours and evens the surface, you often need fewer topcoats.
  • Longer Lasting Finish: Primer extends the life of your paint, especially on exteriors or high-use areas.
  • Smoother, More Professional Look: The final finish looks cleaner, richer, and more polished.

Painting Preparation Tips for Best Results

Good prep makes a world of difference. Before painting:
  • Clean walls thoroughly
  • Repair dents, cracks, and holes
  • Sand glossy areas lightly
  • Remove mould or water-damaged sections
  • Apply primer appropriate for your surface
It’s these behind-the-scenes steps that separate professional-quality results from DIY frustration.

When You Might Not Need Primer

There are a few cases where primer may not be necessary, including:
  • Repainting a light colour over another light colour
  • Previously well-painted, non-glossy surfaces in good condition
  • Using certain self-priming paints (though results vary)
Even then, primer usually improves longevity - especially in older homes or moisture-prone areas like kitchens and bathrooms.

Trust Perth Professional Painters for Flawless, Long-Lasting Results

Whether your home needs a fresh coat of paint or a full repaint with proper surface preparation, Perth Professional Painters ensure every job is done right from the very first step. We use high-quality primers, proven techniques, and expert preparation methods to create a finish that looks better and lasts longer.

If you want a smooth, durable paint job with none of the guesswork, our experienced team is here to help with residental painting across Perth including interior and exterior projects.