What Causes Paint Failure?
Updated: Mar. 02, 2023Professional painting contractor Nigel Costolloe discusses common causes of paint failure and how to fix them.
For most homeowners, peeling paint is a mystery. All the DIY and how-to shows online and on TV typically focus on starting from scratch, or at least with a good foundation. So, what do you do if you encounter failing paint in your home, especially if your home was supposedly “professionally” painted?
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Aesthetic Failure
If you’re dealing with failing paint, you’ll notice one of two types of frustrating flaws:
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The aesthetic flaw, where color coverage is thin or inconsistent, or was applied sloppily which has resulted in drips, sags and spatter.
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A failed adhesion, that resulted in peeling, blistering or otherwise failing.
The first issue is an easier fix. If you’re dealing with poor coverage, you can apply another finish coat to solve the problem. The trim or ceilings can be touched up to hide sloppy cut lines, and drips and sags can be easily sanded down or scraped off. (My favorite tool for scraping is a carbide scraper—it never needs sharpening and it can quickly scrape off the toughest problems while leaving behind a relatively smooth finish).
Since you’re living in the home, you probably care more about the look of the paint job than the previous homeowner or professional who left behind a flawed finish. There are any number of reasons for sloppy work—maybe the painter was working within the confines of a tight budget, or maybe poor eyesight or clumsy hand/eye coordination was at play.
How to Fix a Poor Paint Job
Whatever the reason for the flawed finish, you can fix the issue with the application of an additional finish coat. This coat of paint will provide the color saturation and consistent texture and sheen that marks a careful and pleasing appearance.
When you set about to repair a flawed aesthetic finish, always buy the best paint you can possibly afford. Most homeowners paint once every 7 to 10 years. For something meant to last that long, choosing a cheaper paint to save money is penny-wise and pound-foolish. Paint is one of those products where how much you spend is directly related to the quality of the product.
What Causes Peeling Paint?
The issue of failed adhesion (aka peeling paint), seems more complicated and even overwhelming, but a paint’s failure to properly adhere is limited to essentially one of two underlying conditions: 1. Contamination on the base coat, or 2. Incompatibility of the base and top coats.
Contamination
Contamination includes:
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dust left on the surface to be painted
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kitchen grease or cooking oil fumes creating a slick surface
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dirt on high traffic walls (my kids love dragging their hands along the walls when they walk down the stairs)
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dirty baseboards and stair risers, often coated in floor polish or waxy wood cleaning soaps
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mineral condensates on bathroom surfaces (steam from showers leaves evaporated salts on walls and ceilings, along with shampoo and soap surfactants)
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stain migration
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mildew growth
You can typically spot these contamination failures by looking for small breaks or fractures in the paint film, small blisters, or limited areas of paint failure (like around a door knob, but not the entire door; or only the ceiling and walls directly over a shower stall).
When you’re dealing with contamination, you might see the color of the underlying wood bleeding through the topcoat. This condition also lends itself to the growth mildew and mold in high-humidity environments, like bathrooms (and the entire state of Florida…).
You also may be dealing with wood tannin bleed, which is easily hidden by an acrylic stain blocking primer. This product captures and locks the water-soluble stain in the primer body and prevents it from migrating into the topcoat. Almost all interior wood trim is pre-primed these days, and most painters assume this is a viable field primer. Unfortunately, that’s not true. Wood tannin bleed is a stabilizing primer designed to help the trim resist moisture absorption while it is stored at the lumberyard, or on a jobsite.
Mildew growth on paint, however, is inevitable over time. The best bathroom paint, engineered for a high-humidity environment, contains a mildewcide. But if the bathroom paint is not cleaned one or twice a year, condensates and surfactants become the food source for mildew. Since these form a layer over the paint, the mildewcide does not come into contact with the mildew, and the mildew is left to happily grow in your bathroom.
Incompatibility
This is a more dramatic paint failure. Incompatibility indicates a failure of the topcoat to bond with the previous coat or basecoat. You can know you’re dealing with incompatibility because that topcoat will simply be falling off. In some cases, it will be so fragile it can be easily removed with a fingernail.
How does this happen? This is typically due to a topcoat being applied to a hard, glossy surface without proper sanding or priming. You most often find this type of incompatibility in older housing where old oil-based paint was in use—including clear coats like varnishes and polyurethanes.
How to Fix Peeling Paint
Once you know what caused your paint to peel, you can get to work fixing it. Simply remove the failing paint with a sharp scraper until you reach paint that is sound. Sound paint should be tightly adhered and hard to remove.
Once you’ve uncovered this underlying coating, clean it, sand it, and clean it again. You’ll know when it’s clean enough when it is squeaky-clean to the fingertips and no paint comes off on your fingers.
Next, buy a good quality acrylic bonding primer and apply it to the cleaned area. Allow it to dry, and then add a topcoat. If patching is required, patch after priming, allowing proper dry time (read the labels of all products!). Then, re-prime before painting.
It is frustrating to discover someone else’s incompetence has just added hours to your painting project, but take the time to assess, repair and repaint correctly to prevent repeating the mistake of the previous painter.
Photos: Courtesy of Catchlight Painting
