What Happens If You Put Oil Based Paint Over Latex?

Chloe Meltzer
by Chloe Meltzer
Both oil-based paint and latex paint are great options for any room in the house, but they aren’t exactly compatible. You can put oil-based paint over late, but it won’t always hold well and will eventually crack if you don’t prepare the surface. Whether it be masking and sanding the area or applying primer, let’s take a look at how you put oil-based paint over latex paint.

Whether you already have latex paint on the walls, or you need to paint over latex for another reason, you might be wondering if it is possible to cover them. Typically oil-based paint is a great option to choose for painting, but if you have latex down already, then it is not really a great decision.

You can put oil-based paint over latex paint as long as you properly prepare the surface first. You’ll need to scrape away the layer of latex paint before you can apply a coat of oil-based paint. Putting oil-based paint directly on latex paint will result in splitting and cracking of your paint surface. As the latex paint expands, the oil-based layer is unable to expand with it.

In this article, we will discuss what you need to know about putting oil-based paint over latex, and we will explain precisely how you can do this. If you do it wrong, the layers will separate, and you’ll have to redo it completely. So, by following this guide, you’ll have done it correctly and bypass any of the hassles.

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Tools You Will Need

  • P80 grit sandpaper
  • P150 grit sandpaper and sanding block
  • Soft, damp cloth
  • Masking tape
  • Paintbrushes
  • Water or acrylic-based primer
  • Stirring stick or wooden spoon
  • Oil-based topcoat paint
  • Respiration equipment or dust mask

How To Put Oil Based Paint Over Latex

Step 1: Sanding, Part 1

Because latex is very stretchy, your oil paint will not adhere to it if it is applied directly. This means that you will need to attempt to remove as much of the latex paint as possible. Make sure you take this step very seriously, as it is the reason that this method will work for you. Otherwise, you will achieve a less than perfect result that looks incredibly unprofessional.

Use P80 grit sandpaper for this as it is very coarse and will be able to cut through any varnished or latex painted walls. Take your sanding block and keep the sandpaper wrapped around it. Sand the entire area. The end product of this process should be a completely matte looking surface. This may take you a while, but it is essential you do this properly. Any areas that appear shiny will cause problems down the line with your oil-based paint.

Step 2: Sanding, Part 2

The next half of the sanding needs to be done with your 150 grit sandpaper. This will help you to obtain an entirely smooth surface. After you have completely sanded the area, you should sweep away all of the dust and then wipe your walls with a damp cloth.

Allow the walls to dry before the next step completely. If the walls are too wet when you go to apply the tape, then, of course, it’s not going to allow the tape to stick as sufficiently as it needs to. Eventually, it will peel off and cause more of a problem. It will be impossible for you to finish the job.

Step 3: Use Your Masking Tape

If you have ever painted before then, you might have done a similar process like this. Mask the edges of adjoining walls or trims to make sure you will not have any spillover. This will help you to achieve a clean-cut and professional look.

Step 4: Apply Your Primer

When choosing a primer, you can use either water-based or acrylic primer. This is mainly because both water and acrylics are compatible with latex as well as oil-based paints. These two primer options allow you to create an isolating surface and essentially a barrier between the two.

After painting on the primer, allow it to dry and then follow it up with a second coat. This second coat will help to cover all aspects of the old paint and ensure you will not have any reactions to the new.

Step 5: Apply Oil-Based Topcoat

Topcoat is a fancier way of saying the main paint color. This is your oil-based paint. After painting this on, you can analyze the situation. You may need to add another coat if necessary. Remember, you are going for maximum coverage as you want to see the color and avoid any streaks.

Remove all masking tape while the paint is still a bit wet so that you can avoid tearing it once it is dry. However, the paint shouldn’t be soaking wet when you remove the masking tape. Touch the wall in an inconspicuous spot. Once it’s damp but not wet, you can remove the tape.

Can I Paint Latex Over Oil?

Now that you have painted oil-based paint over latex, you might be wondering if you can do the same in the opposite manner. This is also possible, but once again, it is important to remember that it will not be easy to reverse the process. In order to remove it, you will need to sand it off every time. Sanding and painting over and over again can become a real nightmare. So unless you enjoy this cycle, which most people do not, try to get it right the first time.

Whatever the case may be, if you do decide to use latex over oil-based paint, you will once again need to sand any glossy areas. Suppose possible sand as much as possible all over the wall. This will give you a better chance of having the process go successfully. When painting latex over oil paint, you should use 100% acrylic latex.

What You Will Need

  • P150 grit sandpaper
  • Masking tape
  • Paintbrushes
  • Latex conversion primer paint
  • Stirring stick or wooden spoon
  • Latex topcoat paint
  • Respiration equipment or dust mask
  • Ventilated area to work in

How To Put Latex Over Oil Based Paint

Step 1: Sand The Surface

When sanding oil-based paint before laying down latex, you will want to ensure the surface is fully sanded. The main thing you need to be worried about is having any type of shine being visible. Use 150 grit paper for this sanding and go for a matte look. You can run your hand over the surface, and it should be extremely smooth. If it’s not, you’ll need to continue sanding until it is.

Step 2: Mask The Area

When doing any type of paint, you should always use masking tape to mask the area. This allows you to have clean and sharp edges. It will also keep you from messing up and will allow you to do a professional-looking job without the cost of hiring a professional.

Step 3: Apply Latex Conversion Primer

After sanding and masking the area, you will want to use latex “conversion” primer paint. This is a specific form of primer that helps you to put latex over other forms of paint. Apply liberally and always give this layer enough time to dry.

Step 4: Apply Latex Paint

Lastly, apply your latex paint and let it dry. Do not forget to remove the masking tape while the paint is still wet to avoid chipping, ripping, or breaking the paint off. Remember that it shouldn’t be removed when the paint is soaking wet. Wait until it’s most of the way dry but slightly tacky. This will be the best texture to allow a clean tape removal.

Things To Remember When Putting Oil Over Latex

Keep The Room Ventilated

You will need to keep the room that you are painting in ventilated to avoid the build-up of paint fumes. These are dangerous and can cause irritation of the eyes, nose, or throat, as well as headaches, feeling light-headed, nausea, or even trouble with breathing.

Wear Proper Protection

Always be sure to wear a dust mask while sanding. This will help you to prevent inhaling paint particles, which can cause many health problems and even be deadly in some cases.

Can You Apply Oil-Based Primer Over Latex?

You can apply oil-based primer over latex but the same preparation principles apply as with oil-based paint. As long as you properly prepare the surface before applying the primer, you’re good to go. Not preparing the surface before putting oil-based paint over latex will result in splitting, cracking, and your paint and primer not adhering properly.

How Can You Tell if Your Old Paint is Latex or Oil-Based?

Unless you’re an experienced painter, it’s not always readily evident if latex or oil-based paint was used previously. If you’re applying oil-based paint on top of another layer of oil-based paint, you can skip the sanding and prep steps and go straight to priming and painting. However, if you mistake latex paint for oil-based, you’ll regret it down the road when your paint starts to crack. Here’s how to distinguish between latex and oil-based paint.

Check for Old Paint Cans

The easiest way to determine the type of paint is to check your property for old paint cans that were used for the paint job. If you locate the old cans and can somehow determine that they were used for your specific project, the can will say if it’s oil-based or latex.

Rubbing Alcohol Test

The rubbing alcohol test is another easy, cheap, and fairly safe way to check your paint type. Here’s what you need to do.

  • Take soap and water and select a small and inconspicuous paint area. Behind a piece of furniture or in a hidden corner is best.
  • Wipe a tiny section the size of a dime clean with soap and water. Make sure to let it dry before proceeding.
  • Take a cotton ball and some rubbing alcohol and wipe the area lightly with it.
  • If the paint is present on the cotton swab, you’re likely dealing with latex or water-based paint.

Acetone Test

The acetone test works the exact same way that the rubbing alcohol test does. The only difference is that you should use acetone on the cotton ball instead of rubbing alcohol. If you wipe the paint and nothing comes off, you’re likely dealing with oil-based paint. If you don’t have straight acetone, you can also use nail polish remover that contains acetone.

Latex Paint Test

The latex paint test is often the last resort that people use, mainly because the other ones are easier and quicker. Also, not everyone has latex paint lying around waiting to be used. If you do, however, you can take the latex paint and dab it on a tiny spot of the wall about the size of a quarter. Pick somewhere inconspicuous in case you change your mind about painting.

Next, let the paint dry overnight. Go back when the paint is dry and lightly scratch at it with your fingernail. If the paint comes easily off, the bottom layer is likely oil-based paint. This is because latex paint doesn’t adhere well to oil-based paint and is easy to remove from it.

Wrapping Up

While it’s easy to paint oil-based paint over latex, there are several steps you need to take to ensure a smooth transition. You’ll need to sand the wall down before applying your oil-based paint, and then also apply tape to ensure clean-cut edges. By following the steps in this guide, you can provide a job well done when painting over your latex.

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Chloe Meltzer
Chloe Meltzer

Real estate agent and copywriter, originally from California. Chloe brings her real estate expertise into her writing to create effective and helpful home guides for you! When not writing or selling homes, she spends her time as a digital nomad traveling the world.

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