can you paint water-based paint over oil-based paint?

Are you curious whether you can paint water-based paint over oil-based paint? If so, you’re not alone. Many home DIYers might not even know about the differences between oil-based paint and its water-based counterpart.

Long gone are the days when oil-based products dominated the decorating scene. Water-based paint is more common nowadays, making up the majority of all household paint sales – but many people still need to paint over old oil-based areas. Knowing their distinctions will help you make your painting project a success – so, what are the differences?

• The difference between oil- and water-based paint
• Painting over oil-based paint in 5 easy steps
• Water-based paint on oil-based primer
• Testing for oil-based paint
• Different oil-based surfaces
• Quickfire FAQs

what is the difference between oil-based paint and water-based paint?

Water and oil-based paints have different types of solvents. The solvent is the liquid part that makes it possible to paint – it evaporates and dries after application. Water-based paint (also known as latex paint or acrylic paint) uses water as its solvent, while oil-based uses natural oils or synthetic solvents.

You’ll probably notice the difference in odour. As the solvent evaporates, water-based paints do not give strong or harsh smells. Oil-based paints, though, have volatile organic compounds (VOCs) that give a very strong smell – potentially harmful in unventilated rooms, so get those windows open!

They also vary in finish. Oil-based paints:

• Are high gloss
• Are quite durable
• Take a relatively long time to dry
• Can also fade quickly, yellowing over time.

Water-based paints dry quicker, keep their colour over time, and are more environmentally friendly. Not only can you get great results, but you’re helping animals and the planet too – win, win!

can you use water-based paint over oil-based primer?

In general, it’s not a good idea to paint water-based paint directly over oil-based paints without the proper preparation. This is because oil-based paints have a glossy surface that doesn’t take well to other coats.

We all know that oil and water don’t mix – they’re ‘immiscible’ in scientific terms – and this is the same when covering an oil base coat with a layer of water-based paint. The poor adhesion leads to the painted surface flaking.

After a while, water-based paint on top of oil-based paint will crack and can peel off in large chunks – leaving you back at square one and creating one hell of a mess.

For that reason, painting over oil-based paint is best with careful preparation of the surface before painting. As with all painting projects, we think prep is the most important part of the job.

painting over oil-based paint in 5 easy steps

So, how can you prepare for painting over oil-based paint? Before you apply any paint layers to your walls, some really important tasks will help the job go well.

step 1) prepare the surface

The glossy surface of oil-based paints makes it so difficult for any other paint to bond. That’s why, if you apply water-based paint straight to oil-based, it will flake and crack as the water-based paint pulls away.

So, to get oil-based ready to paint over, you need to take away a lot of that gloss. Dig into your decorating supplies to find some medium-fine grit sandpaper. Then, go over the walls carefully to remove the shiny surface of the paint.

step 2) clean up

Once you’ve sandpapered, wipe away any dust. Then, you’ll want to remove any dirt left on the surface – this will help water-based paint bond to the surface. You can do this with cleaning products like Bartoline sugar soap, which removes dirt and grease before painting.

Remember – safety first. Wear gloves and eyewear to keep yourself safe, then gently go over the surface with your cleaning product a couple of times, allowing it enough time to dry afterwards. You can also use this chance to fix any chips or fill holes if needed, making your water-based paint’s final application even better.

step 3) apply primer

Once you’ve prepared the wall, apply bonding primers and undercoats to help you get a high-quality finish. You’ll usually need one or two coats of primer, depending on the old colour. To know if you’ve applied enough primer, check if any old colour or staining is visible. Remember to allow plenty of drying time before applying new paint.

step 4) apply top coats

Now it’s time to apply your water-based top coats. Use high-quality paints on the treated and primed surfaces. How many coats of paint you need will depend on a few things – usually, two will be needed as a minimum but it’s worth checking. As always, give the paint plenty of time to dry between coats.

step 5) pack up, step back and admire

When you’re satisfied with the job, you can start packing away. Use a planet-friendly product to clean your brushes, put your tools away and ensure any leftover paint is recycled responsibly. Then all that’s left to do is to step back and admire your handiwork.

Following these steps should help you get great results when painting over gloss with water-based paint. It’s all in the preparation.

can you use water-based paint over oil-based primer?

You can use water-based paint on oil-based primer. But, with its environmentally friendly solvents, we’d always think of the penguins and recommend water-based primers instead of oil. You will never find oil-based products on splat!

how do I know if I have oil paint on my walls?

New homeowners might not know the type of paint they’re working on. If you’re not sure of your existing paint base, you can use a cotton ball dampened with a little denatured alcohol. Apply it to a small area you plan to paint over – if no colour comes off, your wall paint is probably oil-based.

what about other oil-based surfaces?

While we’ve extensively covered the process of painting over oil-based paint on walls, it’s essential to consider other oil-based surfaces that may require a fresh coat.

Woodwork, furniture, and trim are common areas where oil-based paints may have been used. The principles for painting over these surfaces with water-based paint mostly remain the same, with a focus on thorough preparation.

Wood surfaces like kitchen cupboards or front doors, in particular, may have a protective finish that requires additional attention before applying water-based paint. Sanding and cleaning are crucial steps in ensuring proper adhesion and a flawless finish. Always check the specific requirements for the type of surface you’re working on, as different materials may demand unique preparation methods.

quickfire FAQs: can you paint water-based paint over oil-based paint?

Oil-based vs water-based: Oil-based painting products are falling out of favour thanks to water-based alternatives, which boast better eco-credentials, healthiness and quality.

Covering with water-based paint: You can’t paint over oil-based paint with water-based paint directly, but you can after some crucial prep.

Doing the correct prep: Always sand the glossy surface of oil-based paint before applying water-based paint. This step ensures better adhesion and a smooth finish.

Identifying oil-based paint: Conduct a simple test by rubbing a small area with a cotton ball dampened in denatured alcohol. If no colour comes off, it’s likely oil-based paint.

Compatibility with oil-based primer: Water-based paint can be applied directly over oil-based primer. However, choosing water-based primers aligns better with eco-friendly practices without compromising quality.

Opt for water-based primers: Use high-quality water-based primers for optimal results and a greener painting process.

Different oil-based surfaces: With proper preparation, water-based paint is suitable for various oil-based painted surfaces such as woodwork and furniture – just follow the same steps as for walls, being careful to treat the surface appropriately.

preparation is key

So, can you paint water-based paint over oil-based paint? The answer is yes, you can. But, as with all paint jobs, the real success comes from careful preparation. We’d also recommend taking the greener water-based choice whenever you can.

To learn more about preparing your walls, using the right paint, and eco-friendly DIY head to our blog.