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Primer & Undercoat

You will never have a perfect coat of paint on the wall without a good primer or undercoat on there first. They’re the difference between a job done OK and one done perfectly. At The Paint Shed, we have an unrivalled selection of primers and undercoats for any paint job inside and outside, with top brands like Johnstone’s Trade, Zinsser & Dulux Trade in stock.

Find your ideal primer or undercoat now, and if you need it in a hurry, we have a click & collect service available from your nearest Paint Shed location.

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What is Primer? 

Primer is a type of paint product which creates an initial coating on a surface. This surface allows for the paint you want to use to adhere as best as possible. To avoid any confusion, if you’re looking to paint a bare surface for the first time, you’ll want to use a primer.

What is Undercoat? 

An undercoat is a chance to give your surface a natural base before you apply new paint, i.e. it is a preparation product to go on already painted surfaces. You want to use an undercoat when you are looking to avoid existing colours from bleeding through.

Are primer & undercoat the same thing?

Yes and no at the same time. An old turn of phrase is “undercoat is always primer, primer isn’t always undercoat”. They have the same function of helping a wall take a fresh coat of paint, but primers are only to be used when you’re painting a surface for the first time.

What should someone with a new surface do?

We tend to think of primers and undercoats as something you place over existing paint or a sanded surface to ensure that the first coat gets the best chance possible to stay on. If you’re working with a new surface, be that a re-plastered wall or exterior wall which hasn’t seen a lick of paint before, you’ll want to get a product specifically formulated to help create a strong bond. Some of the most notable would include Crown Trade New Build Acrylic Primer and Crown Trade Stronghold Undercoat White.

Is it better to use water or oil-based primer/undercoat?

You may know the phrase “the floor is lava”. You’ll want to remember “the wall is water” when deciding whether to choose water or oil-based primer/undercoat.  Water-based undercoats are great for larger surfaces like your wall and ceiling, as they’ll also tend to use water-based paints. Conversely, with doors and skirting boards needing oil-based paint, an oil-based primer/undercoat is your best option.

Which primers are best for metal?

We have over 50 types of metal primer in stock. We would recommend you look at some of the differences in products before deciding on one. For example, Zinsser Allcoat Exterior Satin can be used on most exterior metals without having to sand, while Coo-Var Red Oxide Metal Primer is a good primer for ferrous metal.

How much primer & undercoat paint should I use?

Most primers and undercoats should give you good coverage with just one coating. When you’re working with a bumpy/porous surface for the first time (wood/masonry), you may need two coats of primers. If you’re using an undercoat and you can clearly see colours peeking through after the initial coat has dried, it will need a second coat. 

Getting ready to paint with The Paint Shed

Double-check you have everything you need before using a primer by visiting our tools & accessories section. It has everything you need to get the job done right. 

Don’t forget that The Paint Shed also has a price promise in place to show that our customers get the best deals possible when shopping for paint primers and undercoats, be that online for delivery or click & collect from your nearest Paint Shed location.