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Surfactant Leaching on Interior Walls: Removal and Prevention

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Matt is a professional painter who owns and operates his own painting business, specializing in interior and exterior house painting.

Is your wall paint leaching surfactants?

Is your wall paint leaching surfactants?

What Causes Brown Drips On Walls?

What the heck is surfactant leaching? The term sounds like something from a horror movie, but if you've noticed brown drips on your painted walls, your paint could be leaching chemical surfactants. This problem can occur when fresh paint is exposed to high levels of humidity, but there are other possible causes too that I cover in this article.

Surfactants are additives in household paints that gradually evaporate over time as paint cures, but sometimes humidity interferes with this process and causes the chemicals to rise to the surface sooner and form a hideous brown film that drips. On painted exterior surfaces, this condition usually clears up naturally on its own from rainfall and dry weather, but on interior walls, the problem can really become an eye sore that won't go away until you remove the drips yourself.

Is it Surfactant Leaching or Something Else?

Before you remove the dripping residue from your walls, it's important to determine if it's from surfactants leaching into the paint or from something else. That way you can find the root of the problem and hopefully prevent it from happening again. So what else causes brown drips on walls?

Shampoo and Soap Stains

There are actually a few possible causes. If the dripping stains are on your bathroom walls, the likely cause is chemicals leaching from the paint, especially if the bathroom is very humid and poorly ventilated, but sometimes brown drips and stains appear when shampoo and soap mix with moisture in the air and get deposited onto the walls. Hairspray is another possible culprit.


If you're a smoker, or someone smoked in the house before you lived there, it's very possible the brown drips are the result of smoke damage from nicotine. Nicotine accumulates on interior walls and usually appears as a hazy brown discoloration, but not always. Moisture can cause the stains to drip too and leave brown dripping stains on walls that look similar to those caused by surfactant leaching.

Low Quality Paint

Using low quality paint, or paint unsuitable for humidity, is more likely to lead to surfactant leaching problems. I made this mistake many years ago when I foolishly painted a bathroom with Super Paint from Sherwin Williams, a paint that doesn't like humidity. The paint was exposed to extreme humidity from outside and from the bathroom itself and leached surfactants all over the walls. Needless to say, I had to remove the stains and repaint the whole bathroom with a different product. Not fun.

Can you wash off brown drips on walls?

Can you wash off brown drips on walls?

How to Remove Surfactant Leaching Stains from Painted Walls

Whatever you do, don't paint over surfactant leaching stains. The new paint won't hide the drip marks, and in fact, it can actually make matters worse. The stains will just reappear in the new paint as it dries and you'll be back to square one.

The last thing you want to do is clean, or repaint your walls, only to have the problem come back two weeks later. Before I explain how to remove the ugly drip marks, let's cover how to prevent them from returning again.

Preventing Surfactant Leaching on Interior Walls

In most cases, moisture is the number one reason your wall paint is leaching brown drips everywhere. The problem commonly occurs after painting a bathroom that's too humid and poorly ventilated. If you apply paint on moist walls, the moisture can dilute the paint film and pull the surfactants to the surface.

Make sure the walls are clean and totally dry before you paint. You can use a cheap hygrometer to monitor humidity levels and a de-humidifier to remove excess moisture from the room before and after you paint. If you're re-painting a bathroom with surfactant leaching problems, I would only use high quality paint formulated to withstand humidity, such as Benjamin Moore Aura Bath and Spa paint. Dedicated bathroom paints tolerate moisture a lot better than basic wall paint will.

Refrain from using the shower for at least 24-hours after the paint dries. I would also consider improving ventilation in the room. In a bathroom, the ceiling exhaust fan might be under-powered or you might need to add a second one.

Removing Surfactant Leaching Drips

Ridding your interior walls of those ugly brown drips is actually very easy. The drip marks usually wash off without damaging walls, so in some cases, you can simply clean the walls and not have to repaint the room. But if the walls are completely covered in drips and sticky residue, aggressive cleaning and a repaint might be necessary.

Walls in good condition with only a few leaching marks can be cleaned off with a mild solution of warm water and a little dish soap, but for walls covered in dripping residue, the best cleaner for removal is good ole Krud Kutter Original. This stuff is amazing. You can also use this cleaner to remove dripping stains from soap scum and nicotine too. Make sure you rinse the walls really good with clean water and dry them completely before you paint!

This content is accurate and true to the best of the author’s knowledge and is not meant to substitute for formal and individualized advice from a qualified professional.

© 2022 Matt G.