Do I Need To Prime Stucco Before Painting?

Made of powdered limestone or cement, and blended with sand and water, Stucco cures to a hard and durable masonry surface, known to last for years on end.

However, you may want to freshen up your stucco and give it a new lease of life. This can easily be done with a coat or two of exterior paint.

As long as your stucco is in good condition and is prepped appropriately, paint adheres to stucco well.

Primer is an important step in painting your stucco. The primer will help the paint adhere to the surface properly, and can also be used to block out stains and optimize your results.

We recommend an exterior masonry primer, or one with stain-blocking properties if your stucco is particularly old and marked. A good, alkali-resistant primer is ideal for stucco as it prevents the walls from drawing in moisture which can discolor the paint.

When applying your primer, first brush it around the edges and then switch to a thick-nap roller to apply the primer to the larger areas of the wall. The more textured the stucco is, the thicker the nap of the roller needs to be in order to distribute the paint into the crevices.

A roller grid will help provide a smoother application. This is basically a plastic grid that fits over a 5-gallon bucket which you roll the roller along to get rid of excess paint.

Coat the entire stucco surface with the primer. Avoid applying too much pressure, as you could end up with roller streaks.

Allow your primer to dry for the recommended time on the container.

Should you wet stucco before painting?

In order to understand whether or not you need to wet stucco before painting, we need to quickly delve into the science behind it.

Stucco is hydrophobic, meaning water is a vital catalyst in the chemical reaction that helps this material harden and cure. If you paint high pH stucco too soon, you’ll get color burnout.

Numerous factors can help reduce the pH level, either naturally through rainfall, or through manual hydration – ie. by wetting the wall.

Freshly applied stucco is likely to be highly alkaline or have a high pH. When first applied, stucco can have a pH level as high as 13 but as it cures the pH level drops.

Most manufacturers don’t recommend painting stucco unless the pH level is 10 or below.

You can lower the pH level to around 8 or 9 by hydrating the stucco. Simply spray the entire surface with water until it begins to run off, then allow the stucco to absorb the water, and repeat as needed.

You can do this a few times a day for several days, but the amount of hydration required will depend on other factors such as exposure conditions, humidity, wind levels, temperature, and which direction the walls face.

You can check the pH level with a pH pencil and distilled water. This is done by scratching a small area on the test surface and wetting it with distilled water, then use the provided color chart to match the color of the test area with the corresponding pH color level.

Is it better to roll or spray stucco?

When painting stucco, you have the option of painting it with a roller or with an airless sprayer. You won’t want to use a paintbrush for painting stucco, however.

For smaller jobs, a roller works well, but for big jobs, it’s worth considering an airless sprayer. The sprayer helps get the paint onto the surface, and you can then use your roller to work the paint in and evenly distribute it into the crevices.

Pros of spraying stucco

  • More efficient
  • More even results
  • Paint dries faster
  • More professional finish
  • Better for large stucco areas

Cons of spraying stucco

Pros of rolling stucco

  • Easy to load and use
  • Even coverage
  • Allows you to work the paint into crevices
  • Good for smaller stucco areas

Cons of rolling stucco

  • Paint wastage (use a roller grid)
  • More time consuming

Final Say

Stucco is known for being super durable and hard-wearing, but you can keep it looking its best by repainting it with high-quality exterior masonry paint.

Don’t forget to fill in any cracks and prime the walls first using an alkali-resistant primer, with stain blocking properties if necessary.

Newly applied stucco will need to be hydrated to lower the pH level before painting, which can be done by wetting the walls and testing the level with a pH pencil.

Finally, for getting the best paint application results, we recommend using a paint sprayer and a thick-nap roller to get smooth and even paint coverage.

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