Can You Paint Latex over Oil Based Paint? Get All The Answers!

The simple answer is yes. You can paint latex over oil-based paint if you properly prepare the surface by cleaning, sanding and applying a suitable bonding primer. However, using latex over oil based paint has generally been seen as a no-no, and for good reason. 

Just taking a quick glance at the picture for this blog post will give you an idea of what will happen every single time you do.  Well...maybe not every time. The following article will tell you everything you need to know to avoid problems and produce great results on your upcoming projects.    

Before we get into all of that, let's look at why a homeowner might choose to use latex instead of oil in the first place. 

Latex vs. Oil - What’s the difference? 

Oil-Based Paint

Oil-based paint (sometimes referred to as 'alkyd-based' when synthetic resins are used) generally adheres very well to surfaces because of it's slower drying time, is extremely durable, as well as stain-resistant.  The drawbacks to oil finishes are that they often have a more pungent odor and higher VOC content, are messier to work with and cleanup, don't retain their color and gloss as well as latex, can "yellow" and even become brittle as they age. 

Water-Based/Latex/Acrylic

Water-based (Latex, Acrylic Latex, and 100% Acrylic) paints are more popular because they're easier to work with and clean-up, they last longer, retain their color and gloss better than oil, usually have a more tolerable odor, and in most cases they dry quicker to the touch.  Latex does have it's cons, in that it lacks the durability of oil in many cases, doesn't generally adhere as well due in part to the quicker drying time, and it shrinks as it dries which can cause previous coatings that are not well-adhered to the surface to prematurely fail.

When Should You Use Oil?

(Safely) use Oil-Based Paint over other oil-based paints

Oil-based paint is a safer choice when painting over a previous oil finish because it is more forgiving of marginal surface prep so there is less chance for peeling -- but that doesn't mean you should skip out on surface prep altogether.

Use Oil-Based Paint for a Smooth Finish

When you want a very smooth painted surface -- such as on interior doors, windows, and trim -- oil is an excellent choice because it has self-leveling properties that will reduce the appearance of brush marks and roller stipple, leaving you with an elegant look.

Use Oil-Based Paint for the most durable finish

In applications that call for a very durable finish, as opposed to latex, oil based paints are great at resisting abrasion, scratching, scuffing, and just general abuse.  Outdoor metal furniture, metal hand-railing, and other similar surfaces are good examples of situations where homeowners prefer its use.

Use Oil-Based Paint for a Smooth Finish

Oil-based primers for use on bare wood are probably my very favorite application because they provide benefits that no latex product can come close to matching.  If I'm re-painting exterior wood clapboard siding, I'll always have a can or two handy to use as a spot primer because of its remarkable ability to bond to bare wood. OIl dries more slowly, allowing it to penetrate better into older, dryer wood providing the best bond possible.

When NOT to use Oil-Based Paints

A couple of situations where I try to avoid using oil products are when I'm painting a large interior surface, like walls or ceilings, simply because it's most often not necessary and I don't like to deal with the odor and the cleanup.  I also prefer to steer clear of them when I'm re-painting large exterior surfaces, such as the siding on a home, because I know that it won't hold up as long as an acrylic-latex between re-paints. Oil based paints will chalk and fade much faster than water-based products (particularly 100% acrylic paints).

When Can You Use Latex?

It's generally good practice to use latex over previously-painted latex on any surfaces that expand and contract.  Latex paint films are flexible and they move with the surfaces underneath them, so if I apply a non-flexible coating (which oil is) over a flexible one I'm going to end up with issues that you would expect -- namely cracking, alligatoring, loss of adhesion, etc.

Latex paints (specifically 100% acrylic paints) are the go-to products for exterior home re-paints because they retain their color and gloss much longer when exposed to the sun.  One situation where caution should be used when re-painting with latex is when it's being applied to an older home that has many layers of paint.  The problem lies in the way that latex dries as opposed to oil.  Oil-based products dry through solvent-evaporation and oxidation, whereas latex dries by solvent-evaporation and coalescence.  Those terms don't necessarily mean much to the average homeowner, but what is important to you to know is that latex paint shrinks as it dries.  So if you have old previous coats of paint that are likely marginally adhered to the substrate -- at least in some spots -- your new latex paint can actually pull them off of the house as it dries. 

A Step by Step Guide for Painting Latex Paint Over Oil Based Paint

If you've made the decision that a latex topcoat would be best for your situation, what are the steps that should be taken to ensure that it will last?

Step #1: Clean the surface

As with any painting project, you should remove any dirt, grease, and contaminants from the surface with a good quality degreasing pre-paint cleaner, such as Simple Green, or our favorites Great Lakes Extra Muscle Prepaint Cleaner and Great Lakes No-Rinse PrePaint Cleaner (both available through Sherwin-Williams). These cleaners provide a little extra insurance if your post-cleaning rinse is not quite.  If this is the exterior of your home and you plan to pressure-wash the surface, you can use the chemical injector tube on your pressure washer to apply the cleaner to the surface.  Scrub while wet as needed, and then let the surface thoroughly dry before you move on.

Step #2: Scuff It Up

With a hard coating like an oil-base finish, it is good practice to abrade the surface with sandpaper, or an electric sander, to create a profile for the new paint to stick to.  A medium grit sandpaper (like 220 grit) is good for providing “tooth”, but not making the profile so deep it is visible through the finish. This sanding is not meant to remove paint, only to make the smooth surface rough enough to allow the new paint to bite. After you've lightly sanded, be sure to remove the dust from the surface by wiping it down with a damp rag or tack cloth, or rinse it off with a garden hose or pressure washer if the project is a large exterior surface.  Allow it to dry before proceeding to the next step. 

Step #3: Prime It

Even after scuff-sanding the surface it's a good idea to add an extra layer of insurance that the latex will bond to the oil by applying a coat of an adhesion-promoting primer that is appropriate to the situation that you're working in (interior, exterior, etc.). Sherwin-Williams Extreme Bond Primer is a great choice that can be used on both interior painting and exterior painting projects.

Step #4: Apply Your Finish Coat(s) of Water-Based Paint

When painting over newer surfaces in very good condition, when painting latex over oil (that is still in good condition), and when necessary for adequate coverage, two coats is the way to go. If you’re painting latex over latex, or painting over a surface that has already been repainted multiple times, when color-coverage allows it is sometimes beneficial to only apply one finish coat. 

Choose your preferred method—whether (brush and roller or airless sprayer)—and apply (normally) two full coats of a high-quality latex topcoat tailored for your project. For exterior projects, opt for a premium 100% acrylic paint that comes with a strong warranty.

When deciding whether to use one or two coats, consider factors such as the condition of the existing paint, the number of previous layers, the type of paint you're covering (oil-based or another latex), and how drastic the color change is.

If you’re working with a newer surface in excellent condition, painting latex over oil-based paint that’s still in good shape, or simply need enhanced coverage because of a significant color change, two coats are generally necessary. However, if you’re applying latex over latex or refreshing a surface that has already been repainted several times—and the new color is similar to the old one—a single finish coat may be preferable. Applying extra coats of paint that don’t serve a purpose shortens the overall serviceable life of the coatings system.

Common Questions about Latex Over Oil Based Paint 

Final Thoughts: Applying Latex Over Oil-Based Paint is Possible! 

Thanks to incredible advances in technology, there are very few situations when an oil based paint should still be used in residential painting. Most of the time, the home-use oil-based paints that are still used in today’s world are being used only because of the age-old fear that “you can’t use latex over oil”. Fortunately, this common misconception is just not the case. So yes! You can (and should) successfully paint latex over oil-based paint. Just know that proper preparation is essential to ensure strong adhesion and a lasting finish. Skipping critical steps like sanding and priming can lead to peeling paint and poor durability. Taking the extra time for proper prep will save you from costly fixes later. 

To achieve the best results, follow these steps: 

1. Clean the surface thoroughly to remove dirt and grease. 
2. Scuff sand with fine-grit sandpaper to create a texture for adhesion. 
3. Apply a high-quality bonding primer to achieve a solid bond between the old oil-based paint and the new water-based paint.
4. Use two coats of durable water-based (latex, acrylic-latex, or 100% acrylic) paint for a smooth, long-lasting finish. 

If you need help with commercial or residential painting in Pittsburgh, we have been serving the local community for nearly 20 years. Contact us today for a quote or general questions. We’re happy to help!