You may be wondering what exactly ‘surfactant leaching’ is.
These are the streaks that appear on newly painted surfaces usually a week or two after application.
They can best be described as soapy, oil, or sticky spots that arise several days after new paint has been applied to a surface.
The streaks may be clear or have a range of colors from white to tan to orange.
Surfactant leaching may appear on interior or exterior surfaces.
They are most commonly seen inside the home in bathrooms, the laundry room, and the kitchen.
On exterior surfaces, you can find them on the balcony soffits, under eaves, the exterior broadwall surface, and sheltered areas such as those found in courtyards.
How Does Surfactant Leaching Form?
They form due to the surfactants that are found in water-based paints.
They are crucial to the performance of the paint, providing it with the proper color, stabilization, leveling, and flow.
However, they can also create surfactant leaching when the drying conditions are not ideal.
Under such conditions when the paint takes longer than expected to dry, the surfactants will rise to the surface and create a film over the paint.
This will result in a sticky or oily film that is over the painted surface.
Consider that latex paints are subject to this effect and are quite noticeable with darker colors such as greens or browns.
The same is true for heavily tinted colors as opposed to pastels.
As you may have noticed from the list of places where they are most likely to occur, humidity is a key element.
Areas with a high content of moisture in the air such as bathrooms and kitchens provide the proper conditions for surfactant leaching to occur.
Such poor drying conditions include the following.
- High Humidity
- Lack of Air Circulation
- Cool Air Temperatures
- Cold Substrates
Any or all of these conditions contribute to the likelihood that surfactant leaching will happen on your paint job.
If you do not allow for the proper drying of the surface, then you can expect this effect to appear.
A good example is a new batch of paint around a shower which is then used before the paint fully dries.
This allows the surfactants to rise to the surface and create an oily or sticky film.
The same is true in the laundry room when the dryer dries the wet clothes which create high levels of humidity.
In a freshly painted room, this can add to the drying time and thus create streaks.
Exterior surfaces are not immune, especially if it has recently rained or if condensation is present in areas that do not have much in the way of airflow.
How to Treat Surfactant Leaching Problem?
Remember, surfactant leaching on walls should not be painted over.
Since the new paint will not adhere well, you should fix the problem before you try to repaint the surface.
For interior surfaces, you will need to use soapy water that is applied by a soft cloth or sponge to the area.
This will remove the film rather quickly.
Follow this by adding fresh water to a clean sponge or soft cloth and rinse away the film.
While doing so, you will need to be careful to protect the paint underneath.
This means avoiding scrubbing or damaging the paint as you are removing the leaching.
Plus, it may take more than one wash to fully remove the film, so be patient in your approach.
It is possible, though unlikely that the leaching will actually stain the paint itself.
If that is the case, you will have to repaint the surface. But keep in mind that is rare.
Keep in mind that surfactant leaching does not lower the quality of the paint itself, it just looks unsightly.
But for exterior surfaces, the film will eventually wear away in a month or so without having to do anything.
If you want it removed faster, then just turn the garden hose on the wall and rinse with fresh water.
On exterior surfaces, you can simply rinse away the leaching rather quickly.
How to Prevent Surface Leaching Indoors and Outdoors?
To prevent surfactant leaching outdoors, your goal should be to keep the moisture away from the paint, especially during the paint application process.
To achieve that start painting early in the day and finish before the sun starts to set, particularly if you expect damp and cool conditions in the evening.
This will help to dry the paint quickly.
For indoor areas like bathrooms, kitchens, and laundries, ventilate the area properly and use fans to move the air.
Depending on the conditions, the layer of paint in these areas can take 7 to 8 days before it gets hardened and washable.
Also, for areas like the bathroom avoid using your shower for a couple of days until you see that the paint is completely dry.
This will help to dry and cure the paint faster without getting it subjected to high humidity.
The Bottom Line
Surfactant leaching is not a complex problem to handle.
In most cases (where high humidity is a problem), cleaning/removing the leaching should be a normal part of household maintenance.
Keep in mind, it may take anywhere from two to six months to show the signs of leaching on a freshly painted surface.
So, do not plan to repaint the surface too soon. You should instead aim at fixing the issue by cleaning and removing the high moisture sources if possible.
Jack Luis is a semi-retired painter who loved painting his clients’ ideas on their walls.
He had worked as a painter for more than a decade to serve the customers in areas such as Charleston, Mount Pleasant, Beaufort, Georgetown, SC (South Carolina). Today in his free time, he likes to read and write about the newer techniques that are being implemented in his profession. You may read more about him here or get in touch with him here.
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