Why Paint Wrinkles

By Jim Hingst

Haste makes waste. I should know that by now. But in my rush to get out of the house, I laid the paint on just a little too thick. When I returned from a week long trip, I discovered that what had been a smooth finish had developed wrinkles.  

In this article I will explain, what causes paint to wrinkle; what you should and shouldn't do to prevent this from happening; and what you need to do to correct the problem.

The Causes

Too Thick of a Coating. Applying too thick of a coating of paint is just one reason paint wrinkles.  What happens is that the surface of the paint dries, but what is under the skinned outer layer is still wet.  With the uncured paint trapped under the skin, the dried film has nothing to anchor to. As the dried layer expands and contracts it develops a web of wrinkles.

High Heat. Temperature extremes can also cause wrinkles. Painting outdoors in the high heat of summer can also lead to wrinkling.  When the temperature is hot, the surface of the paint can skin over before the lower layers have a chance to dry.

High Humidity. Uncured paint that is exposed to high humidity, dew or rain can wrinkle.

Uncured Primer.  Applying paint to primer which has not sufficiently cured can result in wrinkles.

Surface Contamination.  Wax, grease or other contaminants on the surface of the substrate can also prevent the paint from anchoring to it.  When painting a non-porous surface, a three-step surface prep is generally recommended. Detergent and water will remove water soluble dirt. Wax and grease remover will clean oily contaminants. A final wipe down of the surface with isopropyl alcohol will remove any residual contaminants remaining after solvent cleaning.

Incompatible Materials. Follow the paint manufacturer’s  recommendations regarding compatibility of primers, paints, thinners and additives.

How to Prevent Wrinkling Paint  

Prior to using primers and paints, make sure all materials are compatible. Coatings from the same family are usually compatible, but not always. It is generally not a good idea to use an enamel with  an acrylic. While the manufacturer’s technical literature can give you some guidance in materials selection and dos and don’ts, the only way that you can be sure if coatings will work in your application is to conduct your own evaluation. That’s why I always recommend to: “Test, Don’t Guess”.

Because waxes, grease and contaminants can affect the adhesion of the paint to the substrate, always follow the manufacturer’s recommendations regarding surface prep, prior to applying the primer.

When painting, patience and attention to detail are virtues.  Follow any recommendations regarding the temperature and humidity parameters when painting.

After priming the substrate, allow sufficient time for the primer to cure before painting, based on the recommendations of the manufacturer.  A coating may feel dry to the touch and not yet be fully cured. Remember that drying is not the same as curing. A dry paint may take weeks to cure, during which the primer will continue to outgas.

After the primer has fully cured, you are ready to paint. If you are working on an outdoor project, avoid painting when the temperature is extremely high. Paint exposed to direct sunlight in the middle of summer can dry too fast. The paint can dry on the surface, leaving the lower layer uncured.Also avoid painting when the humidity is high. 

When using thinner or other additives, thin the paint based on manufacturer’s recommendations. Use the thinner recommended for the ambient temperature in your shop or work area.  Using the wrong thinner or reducer can lead to problems. In some cases, the substrate can absorb thinner, which can affect paint adhesion. 

Whether you are spray painting or painting with a brush, apply thin coats. Painting several thin coats is generally preferable to painting one thick coat. When applying multiple finish coats, allow sufficient drying time between coats.

The Cure for Wrinkling Paint

Even if you have followed all of the advice, that I have outlined, problems can and will occur. What then? There is no easily solution. If the paint wrinkles, you have to scrape or sand it off of the surface. Feather the edges,so your repair work blends in. 

After removing the paint, clean the surface and repaint. If you have to scrape down to the substrate, use the primer recommended for your application. 

Some Final Thoughts

Sometimes wrinkling occurs between different layers of paint because one coat is not chemically compatible with the other coat from a different manufacturer. So why does wrinkling happen when both coats are from the same can of paint?

Here are a few things to remember when painting:

● Prep the surface properly. The substrate needs to be clean and dry.

● Ambient temperature can contribute to wrinkling.  When painting, the shop temperature should not be too cold, nor should it be too hot. It needs be just right – based on the manufacturer’s application instructions.

● Apply thin coats of paint. If the first coat is applied too thickly, the second coat may dry faster. As the top coating contracts in drying, it can pull on the coating underneath resulting in wrinkling.

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About Jim Hingst: After fourteen years as Business Development Manager at RTape, Jim Hingst retired. He was involved in many facets of the company’s business, including marketing, sales, product development and technical service.

Hingst began his career 42 years ago in the graphic arts field creating and producing advertising and promotional materials for a large test equipment manufacturer.  Working for offset printers, large format screen printers, vinyl film manufacturers, and application tape companies, his experience included estimating, production planning, purchasing and production art, as well as sales and marketing. In his capacity as a salesman, Hingst was recognized with numerous sales achievement awards.

Drawing on his experience in production and as graphics installation subcontractor, Hingst provided the industry with practical advice, publishing more than 150 articles for  publications, such as  Signs Canada, SignCraft,  Signs of the Times, Screen Printing, Sign and Digital Graphics and  Sign Builder Illustrated. He also posted more than 325 stories on his blog (hingstssignpost.blogspot.com). In 2007 Hingst’s book, Vinyl Sign Techniques, was published.

© 2015 Jim Hingst