Most of the thermoplastic longlines placed on TxDOT roadways are applied by spraying the hot thermoplastic onto the surface. Therefore, sprayed applications are the major focus of the information in this segment. However, it is worth noting that there are other methods of applying thermoplastic markings to the roadway surface, such as gravity extrusion and ribbon application.

Gravity Extrusion.

Gravity extrusion was the application method of choice for many years, and is well suited for application of thicker markings. Extrusion occurs by pouring hot thermoplastic into a trough or shoe, which has a gate set to produce a desired thickness. However, extrusion is a relatively slow process (3 mph).

Ribbon Application.

Ribbon application uses a pressurized gun to apply thermoplastic in the same manner as the gravity extrusion method.

Hot-Sprayed.

Hot-sprayed thermoplastic is the most common application method used for striping on TxDOT roadways and provides many advantages over other application types. The main difference between sprayed thermoplastic and the other application methods is that the hot thermoplastic is combined with pressurized air in spray applications. The primary advantage to sprayed application is that striping can occur at higher speeds (2–8 mph) and markings are ready for traffic in one minute. Sprayed applications often produce a better surface bond than extrusion and ribbon applications. However, sprayed thermoplastic markings are not as well suited for applying markings thicker than 100 mils when compared to extrusion and ribbon applications. Figure 2-10 shows a typical sprayed thermoplastic application.