Look beyond the sticker shock to fully understand the benefits of UV technology
For many years we have heard of and been introduced to "new technology" that will change the way we refinish vehicles. Most of the time it requires newer products, some equipment changes and training to break our old habits used on previous technology. For a few years now, new technology has emerged that will change refinishing methods. And for an added benefit, at the same time assist with meeting the near future Environmental Protection Agency (EPA) guidelines and Health Hazards we have faced since aftermarket paint coatings were introduced.
Even though ultra violet technology (UVT) for curing is not new, it is becoming more readily available by all paint manufacturers, and those that are looking for a cost-effective solution to increasing productivity are finding it to have very good results.
What is UVT?
UVT is a curing process that uses ultraviolet (UV) or even visible light to polymerize a combination of monomers and oligomers onto a substrate. It causes the paint to cure. The UV product being applied may be in the form of ink, paint coatings, adhesives or even fillers. The process is also known as radiation curing or "radcure" because UV is a radiant energy source. The energy sources for UV or visible light cure are typically medium pressure mercury lamps, pulsed xenon lamps or even lasers. The coatings cured with these light sources are usually clear or very translucent, though thin opaque coatings are possible. Highly opaque coatings are not often effectively cured with UV, because the radiation is typically blocked from penetrating the top surface.
Unlike common isocyanide-based paint systems that require a combination of products to chemically interact to produce a drying and curing process, UVT products are commonly single component and often isocyanide free. Since they are often not reduced with any solvent, they also provide a very low Volatile Organic Compounds (VOCs) alternative to current solvent borne systems.
Where is UVT Used?
As I said, UVT isn't new. Commercial applications of UV curing technology are very diverse in manufacturing, such as in the following applications:
- Coatings on: compact discs, hardwood flooring, upscale shopping bags, optical fibers, furniture laminates, release papers, vacuum metallized plastic, credit cards, beverage cans, photographic film, magazine covers, wall paneling, vinyl floor tile, leather finishes,magnetic media (tape & floppy disks), galvanized metal tubing
- Inks for: lithographic, letterpress, flexographic, gravure and screen printing
- Adhesives for: automotive headlamps, pressure sensitive labels and decals, potting and encapsulation of electronic components, plastic components assembly for the medical industry
- Miscellaneous uses: dental fillings, rapid prototyping resins
Currently in our industry UVT is available for three areas: glazing putty, primer surfacer, clear coats. The application and use of these new systems does require a change in thinking during usage. There's also a need for newer and additional equipment and some new safety practices. From my observations, they are well worth the benefits.
The Differences May Scare You ... Cost
When first looking at products such as a UVT Primer Surfacer, one may faint when they see the first product invoice. One system I reviewed had a sprayable cost for their conventional 2-K Primer Filler at just under $50 per liter. Their UVT product was around $160 per liter. This may cause many to stop right there and refuse to go any farther, but UVT could end up costing less to use than conventional 2-K product.
First, the mil thickness of the above product line usually deposits 1.0-1.5 mils per coat with the 2-K product, so typically two to three coats are applied to a repaired panel with proper flash time required between coats. With air dry, it will take hours to cure to not have any shrinkage to worry about before sanding and finishing. Even with infrared curing, the time is significantly reduced (usually eight to ten minutes), but heat on the substrate needs to be carefully monitored — something all of us have discovered at least once when breaking in a new helper or prep person.
With the UVT primer surfacer each coat will provide approximately 3+ mils deposited, and often the application is only one coat (see photo 1 — one coat application). However, the product must then be cured with a special UV Light source, or in most systems they can be cured by sunlight. This is very nice for the South and on sunny days anywhere. (Maybe paint shops of the future will have retractable roofs when repairers need direct sunlight.) The UV sources will be discussed later in this article, but they do not actually heat the surface. A chemical reaction takes place. This is very beneficial for heat sensitive substrates. Curing takes only a couple of minutes, but each area of the panel where product has been applied must be cured with the special light.Application Differences
The first and foremost concept to remember is that the products will be much more transparent than typical 2-K primers. After the proper application of a single coat achieving approximately 3 mils of build, the repair area will still be visible. This will make some believe they do not have enough product applied. This type of thinking is wrong (see photos 2 & 3 – coverage differences). In addition, clear coats will have a tendency to be very "clear" without the amber tint commonly seen in 2-K clears for UV protection.
Equipment Differences
When the products first came out, they were sold as a "small repair" solution. They included aerosol-canned primers and small handheld lights to cure the products. Even though there are still aerosol-canned products, the lighting options have improved (photos 4-6 – portable light unit). This unit will cure a small area of 10 to 12 inches at a time. Newer options are of course to follow such as a unit that can cure larger surface areas (photo 7 — larger portable light unit).These units are not cheap, but are worth the investment to improve efficiency. A challenge for any light source is to get to areas that may be in the shadows such as the lower rockers, fenders, doors, etc.... This is an important consideration, since every area with product applied must be cured by the UV light source. This is a reason that some paint manufacturers may provide a "hybrid" UV product that does use isocyanide hardener to cure areas in the shadows.
Myths and Misconceptions
Some very important misconceptions have been raised and they need to be better understood.
1) Are UVT materials dangerous? Don't think there are absolutely no health risks associated with this new technology, but overall UVT materials are much less toxic than solvent-based and some of the ingredients in water-based systems.
UVT has a very high or no flash point; emits little to no volatile organic compounds or Hazardous Air Pollutants; has very low systemic toxicity; as a class are not carcinogens (recent long-term skin painting tests showed no carcinogenic effect, and the test materials showed no systemic toxicity); are not fetal or reproductive toxins; are not regulated as RCRA hazardous waste and do not appear on any "Community Right To Know" lists. Moreover, UVT curing materials are not absorbed through the skin like solvents, and they have very low vapor pressures, making inhalation less likely.Good industrial hygiene practices, knowledge of safe handling procedures and worker training are essential for safe handling of any chemical. When these principles are followed, experience has shown that UVT curing technology is safe.
2) Is the UV light used in UV curing a significant hazard? The biological effects of exposure to ultraviolet light resemble the typical symptoms of sunburn. We are all familiar with sunburn, so anyone who might be inadvertently exposed to excessive ultraviolet light would be quickly aware of it. The American Council of Government and Industrial Hygienists (ACGIH) and National Institute for Occupational Safety and Health (NIOSH) have established exposure limits for UV light that are easily met with shielding to minimize escape of ultraviolet light into the workplace. The use of special "sunglasses" is advised if working around the light source when it is in operation.
There are three basic bands for UV light: UV-A, UV-B and UV-C. The typical band that is used to cure our new technology falls into the UV-A band, 320 – 450nm. This is the same band that tanning beds use.
When working around welding equipment we have learned often the hard way to protect our eyes. With UVT it is important to protect your eyes and skin from overexposure, similar to the way those in tanning beds wear protection for their eyes. These may seem very simple and basic, but they are and will be overlooked.
Why Consider UV Technology?
Change is often hard for anyone and adopting this type of technology is no different. The improvement in overall efficiencies may make a change to UVT worth it. It all depends on your business model. Here are a few things to think about:
1) Improved productivity: Since most systems are solvent-free and require less than a second of exposure, the productivity gains can be tremendous compared to conventional coating techniques.
2) Works well for sensitive substrates: Most systems do not contain any water or solvent. In addition, the process provides no heating curing making it ideal for any heat sensitive substrate.
3) Environmentally and user friendly: compositions are typically solvent-free so emissions and flammability are not a concern. Light cure systems are compatible with almost all application techniques and require a minimum of space. UV lamps can be portable units.
For additional information on UV technology go to www.TheBOSs-Online.com and sign in as a free guest. Once you log in, type in "UVT" in the document search box.
Special thanks to Langford's Collision Repair, in Indianapolis, for their contribution of photos and information.
