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.
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.
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).
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.
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.
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”.
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. 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.
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.