History of Glass Beads for Road Markings

Glass beads have always been used to make reflective road signs. If properly embedded in the marking material, the glass beads are able to collect the incident light and reflect some of it back to the light source. It's this ability that makes these small, spherical glass particles unique.

1952: Pocock and Rhodes first studied the principle of glass bead retroreflection.

1967: Dale demonstrated in the NCHRP report and recommended the use of larger size glass beads.

1969: Dale first proposed the best retroreflection of dry and wet reflective marking and glass bead settlement of 60%.

1976: DaForno of Potters presented a comparison of adhesion of glass bead coatings and marking coatings at the TRB annual meeting.

The surface treatment of AC-04 improved the bead-coating adhesion 5 times more than that of moisture-proof glass beads, and 25% better than the uncoated glass beads.

The surface treatment of AC-02 improved the bead-coating adhesion by 10 times compared with the moisture-proof glass beads, and was 50% better than the uncoated beads.

Note: AC-4, AC-2 adopt different coating processes for different marking materials (such as hot melt, epoxy, PMMA, etc.)

1984：Larger glass beads were tested in laboratories and field testing sites in northern New Jersey, providing reflectivity 3-4 times higher than standard beads. And for the first time, the 350 mcd road marking was proposed to provide drivers with more clear guidance.

1986: Timely evaluation of installation with retroreflectometer with the active cooperation of Maryland Department of Transportation. During initial and subsequent evaluations, larger beads proved to be more retroreflective.

1987: Preliminary field trials of large particle size glass beads were conducted in New Jersey. Actual field applications are carried out with thin film materials (epoxy resins) and thick film materials (hot melt coatings, polymethyl methacrylate (PMMA) of less than 20 mil in order to optimize glass bead adhesive systems. Changes in adhesive film thickness, glass bead size, and glass bead surface treatment were evaluated, and reflectivity, durability, and night performance on wet roads were evaluated with portable reversemeters.

March 1987: Painting was done using hot melt type paint according to Florida codes, and a year later a local observer evaluated the site and noted that the site was wet reflective.

August 1987: On a four-lane highway in California. Using a hot melt paint with large particle size glass beads, the site was observed to provide good wet reflection performance 6 months after installation.

In conclusion，high quality reflective road markings can bring more safety to pedestrians and drivers.  Glass beads are a key factor in ensuring visibility of road markings at night. The ultimate purpose of installing and maintaining road markings is to improve road safety; for this, high-quality raw traffic safety materials are essential.

Tory, as a leading manufacturer of glass beads for road markings with more than 30 years-experience, is dedicated to renovating technology and keeping quality high. Tory is glad to offer help if you need glass beads for road markings. And all products can be customized according to customer requirements. For more information, or to get started on your traffic safety solution:  https://www.cntory.com/

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