Why You Need an Undercoat
When it comes to painting a wall, ceiling, or surface, many people are eager to jump straight into applying the topcoat—the colour they’ve chosen to bring their space to life. But there’s a crucial step that should never be skipped: the undercoat. Also known as a primer or base coat, undercoat plays a vital role in preparing a surface properly and ensuring your paint job not only looks great, but lasts.
In this blog, we’ll explore what undercoat does, why it matters, and the key benefits it offers—whether you're painting a new wall, renovating furniture, or freshening up your business premises.
In this blog, we’ll explore what undercoat does, why it matters, and the key benefits it offers—whether you're painting a new wall, renovating furniture, or freshening up your business premises.
What is an Undercoat & What Does It Do?
An undercoat is a specially formulated preparatory layer applied before the topcoat of paint. Its purpose is to seal, smooth, and prime the surface, creating an even foundation for the paint to adhere to. Undercoat can be used on:
✦ New or bare surfaces (like plasterboard, timber, or metal)
✦ Previously painted surfaces being painted a different colour
✦ Glossy or uneven surfaces that need a fresh base
Without an undercoat, the final result can appear patchy, uneven, or may not adhere properly—leading to cracking, flaking, or needing to repaint sooner than expected.
✦ New or bare surfaces (like plasterboard, timber, or metal)
✦ Previously painted surfaces being painted a different colour
✦ Glossy or uneven surfaces that need a fresh base
Without an undercoat, the final result can appear patchy, uneven, or may not adhere properly—leading to cracking, flaking, or needing to repaint sooner than expected.
Top Benefits of Using an Undercoat
☑ Better Paint Adhesion
The undercoat helps the top layer of paint stick properly to the surface. This reduces the risk of peeling or blistering over time—especially important for high-traffic walls, trim, or exterior areas exposed to the elements.
☑ Longer-Lasting Finish
By improving adhesion and sealing the surface, undercoat extends the life of your paint job. It reduces the need for touch-ups and gives you a more professional, polished look that stands the test of time.
☑ Enhanced Colour Coverage
Undercoat evens out colour differences and blocks stains or dark tones underneath. This means your final colour appears truer and more vibrant, and often requires fewer coats, saving you time and paint.
☑ Improved Surface Smoothness
On porous or uneven materials like timber or plaster, undercoat fills in small imperfections, creating a smoother surface for your topcoat. This results in a cleaner, more flawless finish.
The undercoat helps the top layer of paint stick properly to the surface. This reduces the risk of peeling or blistering over time—especially important for high-traffic walls, trim, or exterior areas exposed to the elements.
☑ Longer-Lasting Finish
By improving adhesion and sealing the surface, undercoat extends the life of your paint job. It reduces the need for touch-ups and gives you a more professional, polished look that stands the test of time.
☑ Enhanced Colour Coverage
Undercoat evens out colour differences and blocks stains or dark tones underneath. This means your final colour appears truer and more vibrant, and often requires fewer coats, saving you time and paint.
☑ Improved Surface Smoothness
On porous or uneven materials like timber or plaster, undercoat fills in small imperfections, creating a smoother surface for your topcoat. This results in a cleaner, more flawless finish.
Do I Always Need an Undercoat?
While some modern paints are "2-in-1" (combining paint and primer), using a dedicated undercoat is still recommended when:
- Painting over a darker colour
- Painting new surfaces or raw materials
- Switching from oil-based to water-based paints (or vice versa)
- Painting areas prone to moisture or wear
Final Thoughts on Using an Undercoat
Using an undercoat is one of the smartest things you can do to protect your paint job, your surfaces, and your investment. It’s a small step that makes a big difference—delivering smoother, longer-lasting results that look better and perform better. So, before you open that tin of topcoat, take the time to prep with a proper undercoat. Your walls—and your wallet—will thank you.
Want a second opinion? Our experienced team is happy to inspect and quote—no strings attached.