Since their first use in 1917 in the U.S., traffic marking paints have steadily evolved to fulfill functional requirements as well as comply with environmental challenges for use on asphalt and concrete surfaces. Early traffic paint formulations were based on oils and resins, and dispersed with pigments, extender fillers, and chemicals in a solvent medium.
With the advent of latex emulsions (polymer and rubber dispersions in water) technology in the 1950s, water-borne traffic marking paints and coatings were developed. These offered superior overall performance and durability, in addition to safety in storage, handling, and application. Over the years, water based traffic paints have been greatly improved. Today they are the preferred products in the industry. In addition to conventional traffic marking paints (oil-based and water-borne), thermoplastic and reflective traffic marking tapes are being used in considerable quantities. The cost/benefits analysis dictates the selection of the type the traffic markings used for most projects.
Although traffic markings serve the same basic purpose (clear delineation of traffic lines), they differ profoundly in their composition, properties and durability. Some traffic marking are suitable for temporary markings while others can be expected to last months.
A rundown of paint types
Traffic markings represent a major class of coatings with a myriad of compositions and types:
- Air-drying Paints dry and cure through the process of water or solvent release from the coating. Prominent in this category are latex (polymer/rubber) emulsions and solvent (alkyd oil, resins, chlorinated rubber, etc., based traffic paints).
- Chemically Cured coatings include a multiple component system, which cure and reach the final cure through chemical reaction of two or multiple components, e.g. epoxy and polyurethane based paints.
- Thermoplastic Traffic Markings are 100% composed of thermoplastic resins, pigments, fillers, plasticizers and additive, available in dry powder form in bags. Thermoplastic means melting to a liquid consistency upon heating and solidifying when it’s cooled to ambient conditions. For application, thermoplastic paints are melted and applied at 375 - 400 F. The marking sets up hard when it cools down to the ambient temperature. In this aspect it is quite similar to “hot-melt” (hot pour) crack fillers.
- Preformed Thermoplastic Reflective Tape is the latest generation of thermoplastic markings, which is used in various applications primarily for quick and temporary delineation of traffic.