AS AN INSTALLER OF METAL
roof systems, you rare concerned with proper installation techniques, overall appearance and customer satisfaction. Upon completion of a project, an architect may add to the punch list the need to fix a few scratches that may or may no have been caused directly by your crew. However, because it is part of the roof system, it is your responsibility to correct them. This will be the last step before you receive your final payment, so you could take a sample of the panel, run down to the local hardware store, and purchase an over the counter industrial acrylic or exterior paint that is custom matched to meet your needs. Is this an acceptable solution? The answer is an emphatic "NO".
The paint system used in our industry are factory applied baked-on finishes designed to offer years of little or no maintenance. Chances are if you have worked on a metal roof or wall panel project, you realize scratches occur at times on any one of the many high-performance paint systems used today.
For example, imagine you are installing a Charcoal Gray KYNAR 500 Galvalume standing-seam metal roof on a home and you noticed a couple scratches, some of which are pretty severe and actually could jeopardize the Galvalume coating under the paint. What would you do? Again, knowing that you need to be off this project and on to the next, you might apply store-bought over the counter paint that matches the roof color. There are a few things wrong with this. First, anytime there is a severe scratch it could jeopardize the integrity of the Galvalume/galvanized coating on the steel. The anatomy of a coated carbon-steel panel consists of a core of cold-rolled steel with a metallic coating applied, making it HD Galvanized or Galvalume. The HD Galvanized or Galvalume coating is applied to act as a barrier to protect the core from oxidization (red dust).
The next steps occur at the paint line, where a pretreatment is applied to ensure good adhesion followed by a primer and topcoat. Most paint systems are only 1-mil DFT (dry film thickness). To put this into perspective, that is the thickness of the cellophane used wrap a new CD.
The chance of affecting the core when you scratch the metal panel is pretty good. So before you touch up your scratch, you should inspect the severity of it. The paint will act as a temporary barrier, but you may begin to see red rust develop because the substrate was affected. Consider this-paint doesn't rust, so an indication of red rust as this point is a tell-tale sign of a damaged steel substrate. You should contact your manufacturer to see what it recommends on the proper treatment of the damaged substrate if this is the case.
Imagine you are installing a Charcoal Gray KYNAR 500® Galvalume standing-seam metal roof on a home and you notice a couple scratches, some of which are pretty severe and actually could jeopardize the Galvalume coating under the paint. What would you do?
To repair a scratch, make sure the surface upon which you are going to apply the touch-up is smooth and the substrate is not damaged. Also, make sure it is free of chalk, dirt, moisture and mildew, which could result in poor adhesion. Do not attempt to apply touch-up in the rain or during the morning when dew has formed on the roof. It is important to always check with your manufacturer that supplied the material to you prior to attempting any solution that could potentially damage the paint system and void your paint warranty.
Once the minor scratches are smoothed and free of any agents that could affect the adhesion, apply the touch-up paint in a uniform fashion. If you plan to use a spray, make sure the surrounding panels are covered and protected against overspray. Let the paint dry for at least 48 hours. Once the touch-up has been applied, check for proper inter-coat adhesion. This step is simple: Place a piece of Scotch tape #610 over the touched-up scratches, and rub your thumb across this a dozen or so times with firm pressure. Then, pull the tape back like you are removing a band-aid from a child's are. Examine the tape and panel for signs of paint removal. If the tape removed a portion of the touch-up, this is a sign of poor adhesion and you should call your manufacturer for further instruction.
If there is a large area that needs to be touched-up, using air dry touch up paint is not an appropriate option. You should consider replacing the panel during installation rather than after the fact when it could become problematic.
Keep it simple. If you scratched your car, you would call the dealer to get the manufacturer's recommended appropriate car finish that matches the original finish. There is a reason for this-consistency and color fade over time. If you scratch a Kynar roof, touch it up with a Kynar air dry system. The store bought over the counter paint exterior system may look good today, but in six months, it may chalk and fade differently than the original system. There is a good chance you will void the original paint warranty. We are talking longevity and consistency, not a quick fix; always use an approved paint system.
Most manufacturers sell the KYNAR ADS air dry systems that match the factory applied products. Touch up comes in all forms: 1 ounce (28g) brush top bottles, spray cans, pints, quarts and gallons. Because these can sometimes be tedious, messy and expensive, some manufacturers have come up with creative ways to apply touch-up.
Chances are if you have worked on a metal roof or wall panel project, you realize how easy it is to scratch one of the many high-performance paint systems used today.
Drexel Metals Corp., Ivyland, Pa. (www.drexmet.com) invented the Drexmet Touchup Pen, which is a disposable touch up felt tip marker that dispenses ½ ounce (14 g) of special-formulated Air Dry KYNAR ADS paint system that matches its standard color chart. Andy Anderson president of Interstate Panel, Hamilton, NJ, and current president of the Ultra Seam Group, states that the Drexmet Touchup Pen is one of the most useful inventions the metal construction industry has seen in years because it makes the process easy for contractors to fix scratches and lasts for a very long time.
Metal roofing and wall panel products are continuing to gain market share. There are programs established to create even greater market awareness and reach out to building owners and consumers to educate them about the benefits of the products we sell within our industry. For us to continue this growth and prosperity, we all need to take notice of the small maintenance items like touch up which, if done properly during installation, could save the contractor and manufacturer a potential headache or worse-a damaged reputation.