Most older homes have at least one layer of oil-based paint on the walls, but today, water-based paint is used more often for interior decor due to its lower cost. Water-based, or latex, paints are a type of oil paint that can be thinned using water or turpentine while pure oil paints are paints that do not contain any water content but instead contain natural or synthetic resins.
If you try to put water-based paint over an oil-based painted surface without any preparation, it will not adhere to the wall as it should. The glossy surface created by oil-based paint stops the latex paint from sticking very well. Even the touch of a fingernail will scrape the new paint off because the adhesion will be very poor. But it is not impossible to apply latex paint to an oil-painted surface-- this article lists some tips that may make the process easier.
1. Ensure Safety
Today, all paints come without lead, but in the past, there used to be lead mixed in with paints regularly. Make sure before taking any other steps that your old painted wall is lead-free-- otherwise, using these methods to prepare your wall will create lead dust, which is harmful both to the environment and to your health. Many contractors are qualified for lead paint assessment and removal, so stay safe and hire a professional if you’re unsure.
2. Dirt-free and Clean
The wall to be painted must be dirt-free and clean before further preparations can be made. Use paper towels with some detergent to clean it, but ensure that no water gets into any holes or cracks you might have in your wall. Next, use a paint prep cleaner to de-gloss the oil paint. Make sure that you remove as much gloss as you can. Otherwise, the water-based paint will still have a problem adhering properly.
3. Use Sandpaper and Fix Imperfections
Use sandpaper to remove the last of the gloss from the surface. You might also consider using an electric sander to make the work go more quickly. Fully cover and protect yourself with the proper safety gear including a dust mask, eye protection, and gloves.
Also, use sandpaper to create a smooth surface if you need to fill in any holes or cracks. With a putty knife, apply spackle paste to problem areas and allow it to dry for the recommended time on the container, then sand as needed Clean up any dust left behind by sanding.
4. Use a Primer
With the gloss coat removed from the oil-based paint, it’s time for primer. Apply a latex primer in two thin coats on top of one another, allowing time in between to dry thoroughly. Use a small paintbrush for tight areas, particularly around door and window corners. For larger areas, pour your primer into a paint tray and use a paint roller to apply it instead.
By using the above tips, you’ll create a perfect surface for you to apply your new water-based paint. Additionally, you should have no problems with your paint job lasting if you’ve done everything here correctly.