Secret to Successful Painting of Powder Coated Metal Surfaces

By Jim Hingst 

CC BY-SA 4.0 by Author   Alexandros T

Painting over a powder coated metal surface can be frustrating because it is difficult for new paint to stick to the old coating. Most paint will not stick to slick surfaces. Special preparation and compatible primers are required for success.

Substrate Preparation

I recommend cleaning powder coated metal in the same manner that you would clean a vehicle before applying vinyl graphics.

First, wash the surface with detergent cleaner to remove water based contaminants. Then clean the substrate with a wax and grease remover. The third step is to wipe the surface down with isopropyl alcohol (IPA).

Powder coated surfaces are very slick so paint does not have much to grab onto. To give the surface a little tooth, lightly sand it with 180 grit sandpaper or a red Scotchbrite pad.  After sanding, wipe the surface down again with IPA.

If the powder coating has chipped away from a steel surface and it has started to rust, simply sanding is not enough to ensure good adhesion. You need to sandblast the substrate to remove any rust prior to priming.

Test, Don’t Guess

Powder coatings are high molecular weight polymers. There are many different formulations of powder coatings. Because of the different chemistry, what sticks to one coated surface may not stick to another. This is why I suggest that you “Test, Don’t Guess”.  

Before proceeding with priming and painting, first make sure that the primer paint sticks. After cleaning and sanding the surface, apply a small spot of primer. Wait for the primer to dry. An hour of drying is usually sufficient. Then try to wipe off the primer with a rag. If you can remove the primer or it smears, it’s back to the drawing board.

Primer Paint

Prime the surface with XIM UMA® Primer Sealer. The old time sign painters would use this product when they were repainting a porcelain sign or painting on glass or ceramic, all of which are slick surfaces.

XIM  UMA Bonder and Primer/Sealer

● Excellent adhesion to non-porous "Hard-to-Paint" surfaces

● Bonding primer for painting vinyl, aluminum, galvanized metal.

● Resists wrinkling, blistering or cracking caused by moisture.

● Cures in low temperatures and high humidity.

● Interior or exterior use.

● Low odor/low VOC.

● Accepts all top coats.

Painting

After priming, paint with sign enamel, such as 1 Shot lettering enamels.

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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 450 stories on his blog (hingstssignpost.blogspot.com). In 2007 Hingst’s book, Vinyl Sign Techniques, was published.  Vinyl Sign Techniques is available at sign supply distributors and at Amazon. 

Slides of Jim's Artwork

© 2017 Jim Hingst