Glass beads can be purchased through suppliers who have them in stock or a few manufacturers who produce the beads. These suppliers or manufacturers are good sources for education and training on glass bead application. Be sure to ask them if they have different size beads and when each size is better used. Also ask them for recommendations on pounds per gallon depending on the type of job. And if you're going to purchase a machine to apply the beads, make sure the manufacturer trains you on how to properly work the unit.
Offering glass bead application only adds one step to a contractor's pavement marking service. And if you purchase an application unit, the paint and the beads can be applied by one person. Martinez says all contractors should add glass beads to their bids. But if the customer is unfamiliar with the benefits - and the application process - make sure to educate him or her. Perhaps the most important benefit is the safety factor. But glass beads also offer a protective coating for the marking meaning that it may last longer than a marking without the beads.
Although glass beads offer many benefits, contractors and customers also need to consider maintenance issues. Like any type of glass, these beads are shiny when first applied but they can dull as they are exposed to the elements. Once they dull out, the retroreflectivity decreases. As the beads wear away some of the covered or hidden beads then become exposed to the surface which can result in prolonged retroreflectivity, says Hall. Beads can also dislodge from the material as they wear again causing the marking to lose retroreflectivity.
However, the beads and markings will eventually need to be replaced. Martinez suggests redoing the marking and adding new glass beads at least once or twice a year whether it's a road, airport, or parking lot. Some airports and highways may require reapplication twice a year.
Removal and repainting of markings with glass beads is not the same as regular paint or thermoplastic markings. "If you just stripe over it the build up can get too high and the marking will be more susceptible to chipping or flaking off," Martinez says. These types of markings should be completely removed before reapplication, he adds.
Martinez suggests using a high-pressure washer and eradicator to remove the marking and the beads. But contractors need to make sure they are not tearing up the asphalt with it. Once the stripes are removed, the debris needs to be disposed of properly. This will add an extra disposal cost the contractor will need to consider.
Retroreflectivity of pavement markings is important, and contractors need to be aware of the options for adding or increasing retroreflectivity. Glass beads allow contractors the ability to add beads to their normal marking application without changing the process.
Factors Affecting Bead Longevity
- Average daily traffic
- Temperature, humidity, weather during application
- Condition and type of surface being marked
- Amount of beads and binder being applied
- Uniformity of glass beads in the marking
- Proper application of binder and beads
- Quality of products being applied
- Conditions markings and beads are exposed to after application such as snow, road salt, snow plows, and heavy equipment
Glass Beads in Preformed Thermoplastics
Glass beads are also incorporated into preformed thermoplastics to increase retroreflectivity in the marking. But with preformed thermoplastics, the glass beads are added in the manufacturing process, removing the need for the contractor to add them himself.
"There is nothing special contractors need to do when installing preformed thermoplastic products," says Dan Lang, vice president of business development at Flint Trading Inc. "They only need to follow the application instructions to achieve excellent initial and long-term retroreflectivity."
Preformed thermoplastics incorporating glass beads can be used with all transverse markings including symbols, crosswalks, stop and yield lines, and other single and multi-color markings, Lang says. In the case of long-line markings, contractors might prefer to use a hot-applied thermoplastic or paint with field-dropped beads.