Peeling Clear Coat

A clear coat was applied over an aged door but was not properly cleaned and/or was applied too thin and is now peeling.

Crazing/Cracking

Original factory “SMP” finish develops “spider” cracking (crazing) that when painted over eventually telegraphs through the new paint.

Painting over old paint that has become thin and brittle can lead to cracks, as the new paint hardens and places stress on the weakened underlying layer.

Peeling Paint, What to do?

Now that you know many of the reasons why paint peels, the question is: what can you do once it starts?

The facts are:

• Paint that has lost its adhesion will continue to peel.
• New paint will not re-adhere old paint.
• In some cases, applying a new coat of paint over failing paint can actually accelerate the peeling process.
• The total removal of all previously applied failing paint is the only absolute way to eliminate the problem, but in most cases, it is not economically feasible.
• In many situations, the best you can do is try to slow the rate of peeling through extensive preparation, proper priming, and using a flexible top coat, generally a waterborne acrylic like Endura-Crylic.

Before painting any roll-up door you should first determine if there are adhesion issues

Adhesion Testing

Perform A Simple Tape Test

One of the simplest tests you can do is a 'tape test' with duct tape.

You can see from the tape pull that the paint is not adhered to the substrate.

Cross Hatch Adhesion Test

• Spray Windex over a 2” x 24” area along the rib and valley.
• While the area is wet, use a Scotch-Brite pad to clean the door surface.
• Spray Windex over the surface and wipe dry with a clean, dry cloth.
• At several points on the door, especially where it looks like there might be problems, and at several different locations on the property, score through all layers of paint with a sharp utility knife in a right-angle lattice (checkerboard) pattern, 10 cuts in each direction, roughly 3/32” apart.
• Brush off any detached flakes of paint.

Next

• Apply a strip of high-quality general-purpose masking tape or duct tape to the area and several inches on either side, firmly press and rub into the valley and onto the rib sections. Then, using a pencil eraser, firmly rub the tape over the incisions to adhere the tape as securely as possible. Leave a small portion of the tape available to grab onto.
• Remove the tape by pulling it off rapidly back over itself as close to an angle of 180º as possible.
• This is a quick pass or fail test.
• Acceptable adhesion is 95%, as a small percentage of the paint will pull off where the door was scored. If whole squares between the score lines come off, then the coating has adhesion issues.
• Pull tests are not 100% foolproof. An example is latex paint applied on a glossy surface, which will generally adhere until it is wet.
• Compare to the ASTM Adhesion Standards in the image below for results.

If you compare the previous image with the tape pull to this chart This would rate a “2B” and would indicate moderate adhesion issues.

Repainting a Job with Peeling Paint

Remove Paint

• Remove as much of the failing paint as possible.
• It is not always possible to remove all the paint, so it is imperative that the new paint adheres to both the bare metal and any existing paint.

Prime and Top Coat

• All bare metal and areas where peeling paint was removed should be primed.
• A “peel stop” type primer should be brushed on all edges.
• Any curled or lifted edges need additional scraping and then should be sealed.

Sealing Edges

• All edges where peeling occurred should be sealed with no curling or raised edges.
• After applying the first coat of paint, inspect peeling areas. Any raised or curling edges should be scraped, primed with Peel Stop using a brush, and touched up by brush to completely seal the edge.

Loose paint should be removed and edges sealed.

Best case example.

What Paint to Use?

• Some types of paints can actually cause additional failure when applied over an existing coat of paint that has adhesion issues.
• Generally, a high-quality acrylic latex paint with excellent bonding and adhesion characteristics, good elasticity, and good touch-up capabilities, like Endura-Crylic, is the best option.
• Avoid alkyds, polyurethanes, epoxies, and other hard finish products that can exacerbate an existing problem.
• The Chem-Bake system is not recommended for doors that have peeling or adhesion issues.

Annual or Semi-Annual Touch-Up

• Even after all of these steps are taken, it is likely that some areas will continue to peel.
• If left bare, peeling will accelerate, and the peeled edges, when exposed to the weather, will cause the issue to spread quickly.
• A yearly or semi-yearly touch-up of all peeled areas should be done to prevent this from happening.

How to Prevent Future Coating Failures

• Understand the situation and the application for which the coating is being used.
• Use the right product for that situation or application.
• Know and follow all application specifications, including:
• Proper surface preparation
• Applying the product during the appropriate environmental conditions
• Quality workmanship in the actual application
• Proper care, including refinishing before the coating reaches its maximum life expectancy
• The cost of shortcuts will never go away until the door is replaced.

How to Evaluate Workmanship Quality

• Basic things to evaluate while the job is in progress:
• You can tell a lot about a crew by just observing. Some of these things may seem trite, but they can give you an idea of the quality of the crew and their professionalism, which often reflects in their workmanship.
• What is the weather like? Does it meet the environmental conditions?
• Job organization: Does the crew appear to be efficient? Is the job site organized/clean? How are they dressed?
• Prep-work: Evaluate the doors just prior to being painted.
• Overspray: When sprayed at the proper pressure, Endura-Clad coatings produce very little overspray. If the applicator is covered in overspray, they are probably not spraying correctly.
• Do not overlook poor workmanship!