You may have begun to hear a buzz in the industry about ultraviolet (UV)-cured coatings. If you aren’t sure what that is, you’re not alone. But it’s growing louder, and the legion of supporters continues to grow.
In simple terms, UV curing involves a chemical process called cross-linking that instantly changes a liquid UV coating into a completely dry, diamond-hard finish at the very moment it is exposed to UV light.
The technology behind UV curing has been available for decades. Unfortunately, it was always limited to the factory setting, as the size and cost of the equipment was prohibitive for field applications. But over the years, manufacturers in the automotive, aerospace, and flooring industries have proven these UV curable coatings to be durable, reliable, and long-lasting finishes.
Recent advances in lighting and power supply technology have given rise to the development of new “portable” UV curing equipment. Coating manufacturers began formulating specially designed UV-curable coatings for site-applied applications. These are available in a variety of colors and sheens, and most have an unlimited pot life. As a result, the benefits of UV finishes are now available to contractors refinishing a variety of surfaces.
There are three compelling reasons to use UV-cured coatings:
1. Speed: The number one reason people choose UV coatings—they cure instantly. UV curing equipment can cure the coating faster than it can be applied. This eliminates the guesswork involved in drying time, and surfaces can be put back into service immediately.
2. Durability: UV coatings are the longest-lasting finishes available. Lab tests for abrasion have shown they are at least three times more durable than standard epoxy or urethane coatings. And there is no other finish available for floors or countertops that can match the chemical or stain resistance of UV coatings.
3. Green: UV-cured coatings emit zero, or near zero volatile organic compounds (VOCs), depending on the formulation. This means there are no lingering odors or adverse health effects.
Portable UV curing equipment is divided into two categories, based on the size of the machine and its intended use. The first are floor models, which are larger, heavier, and come equipped with wheels so they can be rolled over the coated surface. The effective cure rate will vary between machines and is determined by both the power (UV light output from the lamp) and size (the width of the cure path).
Today’s floor curing machines can vary greatly in power output, from just a few hundred watts up to 10,000 watts. The size, or width of the area they can cure in one pass, also varies from 12 to 34 inches. To ensure that the coatings are cured to the manufacturers’ specifications, the more advanced machines are self-propelled and feature a speed indicator in feet per minute.
By simply entering a speed on the control panel and squeezing a trigger on the handle, the operator can control exactly how fast the machine travels over the surface to be cured. It is essential to follow the manufacturers’ curing specifications. Not doing so can cause premature failure of the coating, or result in an incompletely cured surface that may be marred by typical floor traffic.
The second category is the handheld models. These are much smaller and lighter and are designed to be held directly over the surface to be cured. Handheld machines typically range from 250 watts to 1800 watts of power, with an effective curing width of 6 to 12 inches.
These are used extensively for refinishing raised and irregular surfaces such as countertops, bathtubs, and sinks. They are also an essential part of the floor coating application and for curing areas such as corners, stair treads, and under stationary fixtures. Some manufacturers offer accessories like telescoping extension handles and wheels that offer the convenience of floor machines in tighter spaces. In short, a handheld unit is best used everywhere a floor machine can’t reach or fit.
The lamp itself is at the heart of this technology. In addition to a metal element, the core gas of the lamp is made up of either argon or xenon. Although less expensive, argon lamps take time to both warm up and cool down, and require some form of mechanical shutter or holster to block UV light during this period.
Continuous-wave xenon lamps instead start instantly and do not require a shutter or a warm-up or cool-down period between uses. This shortens the time needed to complete a job and makes the operator more productive.
Safety and training
UV curing equipment is safe when operated properly. Unprotected exposure to strong UV light can cause serious skin and eye damage. It is essential that the operator be trained in proper operating and safety procedures, and for all personnel in the vicinity to be equipped with protective safety equipment. Wraparound safety glasses and/or face shields with polycarbonate lenses and opaque clothing such as Tyvek UV protective wear will block almost all of the UV light.
Many equipment manufacturers offer safety training and materials which should be utilized to ensure safety of the operator and others on the jobsite. Most also incorporate high-tech safety features to help contribute to a safe working environment. Features such as integrated light shields to prevent stray UV, thermal sensors to prevent overheating, or non-movement sensors to prevent floor scorching are all designed to provide safety for the operator.
Some equipment manufacturers even include tilt angle detectors and proximity sensors in their handheld units to reduce unwanted UV exposure by turning off the UV light source when the unit is held at an unusual angle or is not near a surface. All units have a kill switch conveniently located near the handle
UV curing is a proven technology which addresses many of the problems and shortcomings inherent in conventional coatings. Waiting hours between multi-coat applications, or days before curing is complete and the surface is put back in full service are no longer concerns. After experiencing the significant benefits of UV-cured coatings, you and your customers may never settle for conventional surface coatings again.