This article is in active development and should not be considered accurate nor complete.

This guide provides a step-by-step process for professional painters to efficiently evaluate, prepare, and paint roll-up doors using the Chem-Bake® system. Each section is designed to help avoid common mistakes, achieve high-quality results, and ensure longevity in the finished product.

Understanding the Challenge of Painting Roll-Up Doors

A typical 8-foot-tall roll-up door has 26 ribs and 104 "corners" and is factory-coated with a Silicone Modified Polyester (SMP) coil coating. The corrugated surface consists of many alternating vertical and horizontal planes. Over 20% of the surface area functions as a horizontal "shelf," where road grime, dirt, and water accumulate, making it particularly challenging to properly prepare and coat. Each missed area becomes a potential point of failure for a new coating.

Silicone Modified Polyester (SMP)

Silicone Modified Polyester (SMP) is a durable coating commonly applied to coil-coated steel used in self-storage roll-up doors. It offers enhanced resistance to weathering, UV rays, and corrosion, providing a long-lasting finish that retains color and gloss, making it well-suited for the self-storage industry. However, SMP can present adhesion challenges during repainting, which will be addressed in the surface preparation section.

Additional Resources

• Anatomy of Self-Storage Roll-Up Doors: What to Know Before Painting – painting roll-up doors may appear deceptively easy but here are a few things to understand about roll-up doors.
• Coil-Coated Steel: Revolutionizing Self-Storage Construction – a brief explanation of what SMP is.
• Chem-Bake 1201 System Guide (PDF) – this document forms the basis for portions of the guide you are now reading. It is provided here as a convenience should you find it useful.

1. Evaluate Door Condition and Select Coating

Overview:

Inspect the door for surface issues such as chalking, peeling, rust, cracking/aged-out paint, or glossy surfaces which might present adhesion problems . Determine if any issues can be remediated and if the door is a good candidate for the Chem-Bake® system, or if existing surface problems cannot be adequately remediated, whether Endura-Crylic would be more appropriate.

1.1. Inspect Door

• Make a careful inspection of the doors and identify surface issues like chalking, peeling, rust, excessive previous layers of paint which might not withstand the strong bonding process of Chem-Bake, loss of paint integrity or brittleness due to age, and any slick glossy surfaces that need to be abraded.

1.2. Adhesion Testing

• Perform adhesion testing to verify the existing paint is firmly attached and will not be pulled off by the newer coating.

Additional Resources

Adhesion Testing - Discusses simple tape pull and cross hatch adhesion testing

1.3. Analysis

Based on your inspection and testing you should now be able to determine if the doors are suitable candidates for the preferred Chem-Bake® system by considering the following questions:

Q: Is the existing coating in generally good condition, with only chalk, scale rust, or peeling that can be remediated to provide a sturdy substrate for Chem-Bake?

If you answer 'Yes' to this question, then you should use the Chem-Bake® system. Chem-Bake is the preferred system for all roll-up doors as it provides the most robust, long-lasting results, unless there is a coating failure issue that cannot be reasonably resolved.

If you answered 'No' to this question then the new question becomes:

Q: Does the existing coating exhibit two or more of the following coating failure conditions:

1. Fails the cross hatch adhesion test with 15% or more of the area affected, as shown in the ASTM Adhesion Standards diagram available midway down this page in the section labeled Cross Hatch Adhesion Test (see the examples starting with 'ISO Class 3/ASTM Class 2B' and below).
2. Exhibits widespread peeling, bubbling, sagging, or cracking involving more than one layer of paint that cannot be reasonably remediated to provide a stable surface?
3. Does it show show evidence that it has been painted many times, with a thick, brittle or failing substrate and present a high likelihood of responding poorly to an additional urethane coating?
4. Is the existing coating 'aged-out' paint or SMP that has become brittle, cracks easily, has lost integrity, and is pulling away from the underlying steel door, making it unlikely to resist the bonding action of a urethane coating?

Answer: If two or more of the aforementioned conditions exist and the problematic issues cannot be reasonably resolved, then your remaining product choices are Endura-Crylic, possibly with the inclusion of Bond-All Bonding Primer. However, if the cost of refinishing, especially when weighed against the age and expected appearance of the refinished door, is deemed unacceptable, replacing the door may be the best option.

Additional Resources

• Paint Failure Causes: Part 1 and Paint Failure Causes: Part 2 – describes common causes of paint failure, including improper surface preparation, with images illustrating types of failure.

2. Surface Preparation

Overview: Surfaces to be painted should be clean, dry, and free from oil, dust, grease, dirt, chalk, rust, loose or peeling paint, and all foreign matter. Conduct adhesion tests where needed.

2.1. Cleaning and Chalk Removal

• Clean and remove all chalk, dirt, grime, and other surface contaminants using Zap-It Chalk & Grime Buster per label instructions. Care should be taken to remove lubricant sprayed around door lock areas and track, and to clean the edges of the door curtain closest to the track and the uppermost edge where it bends into the unit.
• Glossy or smooth hard surfaces should be dulled using abrasive brushes, sandpaper, or abrasive pads. A completely clean and sound substrate with no dust, chalk, or other surface contaminants must be obtained prior to applying any coating or primer. If dust, chalk, or dirt remains, repeat the cleaning process.

Additional Resources

• Zap-It! Chalk & Grime Buster (video) - demonstrates the cleaning process.
• Zap-It! Instructions (pdf) - basic instructions for usage

2.2. Handling Peeling, Rust, or Other Surface Issues (If Applicable)

Peeling

Paint peels for many reasons, and it is important to do a little detective work to try to determine the problem and possible solutions. For example, widespread peeling that reveals a previous layer of slick and glossy paint, the original glossy SMP coating, a layer of chalk, brittle aged-out paint, or excessive accumulated layers of paint peeling will likely not be resolved by applying more paint.

When dealing with peeling, it is a good idea to perform an adhesion test. This will help determine how serious and widespread the problem is.

Minor Peeling

• Remove any loose or peeling paint and lightly sand the edges.
• Use Peel Stop on the edges of the peel areas to help stabilize them.
• Spot prime these edges with a suitable bonding primer.
• Sand or abrade the existing layer if it is slick or glossy.
• Use an appropriate primer like XIM UMA or Bond-All Bonding Primer if warranted.

Systemic / Wide-Spread Peeling

• Inspect the peeling to identify the cause(s) of the failure.
• Peeling can occur when new coatings are applied over failing coatings, chalk, grease, wax, silicone, or glossy surfaces like SMP without proper abrasion. In such cases, the new paint must adhere to a hard-cured, well-adhered layer; otherwise, it will "inherit" the underlying paint failure. Pressure washing and scraping down to a layer with good integrity may be necessary.
• You can apply the process detailed in the 'Minor Peeling' section to larger areas, and if this results in a surface with good integrity that can handle Chem-Bake's strong bonding action, it may still be the recommended solution. Keep in mind that removing large areas of peeling paint, while leaving some of the old coating intact, will be visible in the final finish..

Additional Resources

• How To Prepare Roll-Up Doors with Peeling Issues - a deeper dive into handling roll-up doors with peeling issues
• Refinishing Metal Roof with Wide-Spread Peeling - not related to roll-up doors but useful if your project includes SMP coil-coated roof panels with peeling issues.

Using Endura-Crylic

• If the current substrate has structural issues that prevent the use of Chem-Bake and you opt for Endura-Crylic, you should still follow the surface preparation steps outlined in this guide. Bond-All Bonding Primer can enhance the adhesion of Endura-Crylic, especially over urethane coatings or problematic surfaces.
• Apply Endura-Crylic according to the manufacturer's instructions.
• Endura-Crylic will continue to strengthen as it cross-links over a 30-day period.
• While Endura-Crylic is a premium, more flexible coating, it lacks the bonding strength and durability that Chem-Bake achieves on a stable substrate.

The likelihood of peeling or other coating failures depends on the product used and how effectively you address underlying issues.

If the required work is deemed too costly or labor-intensive, or if the anticipated quality of the finish over the accumulated imperfections is likely to be unacceptable, replacing the door may be a more cost-effective solution.

Rust

Steel rust and mill scale must be removed using sandpaper, wire brush, or another abrading method. Any bare steel must be primed with a suitable primer product such as XIM UMA or Bond-All Bonding Primer the same day as cleaned.

2.3. Achieve Proper Surface Profile on Slick, Glossy Surfaces

• The SMP coil-coated steel of a roll-up door offers a slick, glossy, solvent- and scratch-resistant surface. These are some of the strengths but also make SMP notoriously difficult to paint, or rather make paint jobs more likely to fail if the surface is not adequately prepared. It is essential that after cleaning and chalk removal, if the surface is still slick, smooth, or glossy, you create a surface profile by abrading it with a Scotch-Brite type pad. This abrasion of the surface will provide a way for the new coating to bond to the existing SMP surface.
• This same approach applies to surfaces that were repainted with performance paints like Chem-Bake One-Step that provide a similar glossy, slick, and hard surface. If the old surface is still slick and glossy, you must create a surface profile, and this is true even if you are using a primer first. The new coating must bond with the underlying coating or eventually it will peel.

Additional Resources

• Paint Failure Causes: Part 1 and Paint Failure Causes: Part 2 – describes common causes of paint failure including improper surface preparation with images illustrating types of failure.

3. Considerations Before Painting

Overview:

Monitor environmental conditions and choose appropriate equipment. Plan the painting sequence based on layout, access requirements, and environmental conditions.

3.1. Environmental Conditions

• Monitor temperature, humidity, and dew point.
• Understand the impact of environmental conditions on curing and pot life.

3.2. Equipment and Spray Tips

• Select the appropriate spray tip for the job.
• Use dedicated hoses based on the type of paint you are using (solvent or water-based). Be sure to flush between uses to avoid blowing out previously catalyzed paint that can clog your spray tip and ruin the finish.

3.3. Plan Your Job

• Start with doors farthest from the entrance to allow yourself a couple of doors to perfect your approach.
• Take the sun into account when you plan which doors to paint first as it will affect the dry time of your doors and the pot life of your paint.
• Account for customer access and parking during the job to reduce the risk of overspray to vehicles and damage to the finish when doors are accessed with paint that is not fully cured.

4. Masking and Protecting

Overview:

Mask surrounding areas, including walls, floors, hasps, locks, bottom rail, and seal. Check for nearby cars and trucks that might be at risk for overspray.

4.1. Protect Surrounding Areas

• Mask adjacent walls, floors, latches, locks, bottom rail, and so on.
• Ensure customer access areas are shielded.
• Be aware of overspray zones. Chem-Bake products have high adhesion properties.

5. Application Guidelines

Overview:

Prepare and mix the paint, then apply using proper spray techniques to ensure even coverage and avoid common application issues.

5.1. Airless Sprayer

Use spray equipment that delivers paint at an even consistent pressure without “surge.” The sprayer, hoses, and gun must be thoroughly clean and flushed with solvent. Always use a hose that is dedicated for spraying solvent-based coatings, separate from spraying water-based products. Spray with the least amount of pressure that still atomizes the paint properly. Recommended tip size and type: .010 -.014 fine finish.

When spraying, use a 50% overlap with each pass of the gun to avoid holidays, bare areas, and pinholes. If necessary, cross spray at a right angle. Application in two light coats is generally better than one heavy coat.

5.2. Prepare Paint

• Mix the paint according to the manufacturer’s instructions.
• Catalyzed paint has a specified pot-life and cannot be reconstituted by adding catalyst or solvent. Account for pot life and mix only the amount of paint needed for each session to avoid waste.

Additional Reading

• Airless Spraying Guidelines (PDF) – provides airless spraying guidance on selecting spray tips, adjusting pressure, and achieving consistent, uniform paint application.

6. After Painting

Overview:

Inspect the painted surface for any imperfections or missed spots and complete cleanup of materials.

6.1. Review the Job

• Inspect the painted surface for workmanship issues, correct coverage, missed areas, especially if the primer or previous coating is a similar color to the new paint, dry spray, drips, or other issues which can become a point of failure for the new coating.
• Ensure proper cleanup and disposal of materials.

6.2. Clean-Up

• Clean spills and spatters immediately with acetone. Clean hands and tools immediately after use with acetone or lacquer thinner. Never leave material in equipment when not in use. Dried paint film, spray equipment, and mixing equipment can be cleaned by soaking and scrubbing with acetone.

Disclaimer: The information provided in the Self-Storage Learning Center is for general informational purposes only. While we strive for accuracy, All From 1 Supply makes no guarantees regarding the completeness or reliability of the information. Use of this content is at your own discretion, and we encourage independent verification before making decisions based on the material.

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