How Can I Tell if My Wall Paint is Oil or Latex, and Does it Matter?

Live a while and you’ll discover opposites often attract, but that doesn’t make them attractive. Like when your kid mixed the sugar and salt in those birthday pancakes. Or that time your high school crush mixed up the shampoo and hair coloring.

The same goes for your walls. Water and oil-based paints mix about as well as literal oil and water.

Why you shouldn’t mix oil-based paint and latex paint

Before repainting your walls, determine what kind of interior paint you already have. If you don’t, you risk a leaking, streaky nightmare. This is because latex paints won’t adhere to walls covered with oil-based paint and vice versa. They are literally oil and water, and they want to stay separated from each other.

When we’re talking about “latex paints” we’re really talking about water-based paint in the context of home interior painting. Acrylic paints are also water-based paint, but acrylics are best for painting canvases with landscapes and bowls of fruit, not your walls.

Don’t let the word confuse you, either. “Latex paint” sounds like it’s based on rubber, but modern latex paint contains no rubber. It’s mostly water. 

Latex paints used to have rubber in them decades ago, but the name has stuck around despite a reformulation — sorta how Cheetos don’t actually contain any cheese anymore, but we still call them that.

Try the water and alcohol test to test for oil-based paint

If you’ve just moved into a house and need to figure out what kind of paint is on your interior walls, there are two ways to test.

  • Look for old cans in the garage or closets. Most people keep old paint lying around long after its use-by date. But they can tell you the brand and formula of the paint. If you’re lucky, it might even tell you what color the paint is in case you want to buy more at your local hardware or paint store.
  • Use alcohol on a cotton swab. Clean a small spot on the walls with a clean towel, dish soap, and water. Pick a corner in the back of the room that isn’t noticeable just in case something rubs off. Then after it’s dry, soak a cotton ball with some rubbing alcohol and rub it over the wall. You’ve got latex paint if the paint comes off onto the cotton swab. If it doesn’t, and the cotton ball is clean, you have oil-based paint.

This test also works for furniture, by the way. 

Hire the pros to finish up; oil or latex paint doesn’t stop us

You can apply latex paint over oil-based paint or vice versa by sanding the walls down and adding a coat of primer. This requires more than a bit of elbow grease because all the sanding will wear down your tolerance real fast

It has to be a smooth finish, too. This might require repairing plaster or drywall that’s damaged on an older home because as you sand the wall, the surface can wear unevenly or suffer deterioration.

The more straightforward solution is to use the original paint and continue painting latex on latex paint or oil on oil-based paint. But as a general rule, we don’t like oil-based paint anymore. Given a choice to use oil or latex paint, we’ll pick latex most every time.

Historically, oil-based paint adheres better than water-based paints. They looked smoother with fewer brush strokes, and they created a rock-hard finish that was pretty good for exterior painting jobs.  

But oil paints are inherently oil-based. They have obvious environmental concerns, take much longer to dry than latex paints, and they’re more challenging to clean up if you spill any. Modern latex-based paint solves all these problems, dries faster, reduces fumes, and doesn’t pose as many health risks to you or our painters.

Since oil paint is “harder” than latex, it’s ideal for doors and trim because those areas often get the most contact from scuffs, hands, oils, and other abuse. Still, about the only time we use oil-based paint is if our customer has a preference for oil-based paint, or if we are painting over an existing oil-based coating. Plus, it’s difficult to find a true oil-based product now, so we prefer to work with Benjamin Moore’s Advance water-oil hybrid. Advance is technically an oil-based paint, but can be cleaned up with water before it dries. Once its dried, then it acts more like a traditional oil-based paint and more importantly will adhere to existing oil-based paint. 

Furniture and wood surfaces on things like deck swings make useful spots for oil-based paint, too, and since they’re outdoors, the fumes aren’t as dangerous to people and pets.

If all that sounds like a job you don’t have time to do or the desire to tackle, let the professional painters at Woodiwiss Painting bring enough staffing to get the job done right. We’ll sand the old oil paint off, apply a bonding primer, and lay down a fresh coat on the surface. All our jobs feature a second coat after the first is dry, too. Contact a paint pro with questions or to get started.