Tim Wehner, worldwide business development manager with Graco Inc., says thermoplastic should only be applied once the surface temperature is above 50°F. If applied below 50°F the bond will be weak and will not last. The pavement surface must also be clean, dry and free of debris, other markings, and curing compounds, McSwain says.
There are three methods for thermoplastic application: spray, ribbon, and extrude. With an extrude application, the application equipment is in direct contact with the pavement surface when applying the material. Because of this, the application equipment must be driven at slow speeds, Hendrickson says.
In a ribbon application the material is applied with a ribbon gun that is elevated off the ground about 1 to 1½ in., Hendrickson says. The gun lays down a ribbon of thermoplastic material on the pavement surface. Since the gun is not in direct contact with the pavement surface, application equipment can travel a little bit faster than when applying an extruded line.
Thermoplastic can also be spray applied. The spray gun is about 4 to 5 in. off the surface, Hendrickson says. The spray gun uses atomized air to apply the thermoplastic material to the pavement surface. This application process can allow equipment to travel faster than both ribbon and extruded applications.
A successful application will hinge on the temperature of the material, Nall says. If the thermoplastic material is not heated to the proper temperature it will not bond with the surface. If you're adding fresh material into a pre-melting kettle that is already heating material, pay particular attention to the temperature of the material when it is applied. The fresh material is at a lower temperature and will drop the temperature of the material it is added to, Nall adds.
Moisture on pavement surfaces and/or cold temperatures will result in a poor bond with the thermoplastic material. The condition of the surface will also affect the bond of the material. Material manufacturers suggest using a primer prior to thermoplastic applications on concrete or older asphalt surfaces. Wehner suggests using a primer when the surface adhesion is in question to assure superior results.
The biggest investment when getting into thermoplastic pavement marking is the equipment. And what equipment a contractor should purchase depends on the size of the company and the type and size of the jobs the contractor will be doing.
For contractors doing mostly intersections, parking lots or smaller jobs, a handliner will be the equipment choice. Handliners are preferred for jobs requiring detail work where a larger, less-mobile truck will not work. Most are walk-behind units but some have a ride-on attachment option available for increased productivity, Wehner says.
Contractors should try to avoid using their handliners to heat the thermoplastic material. "Handliners are made for applying the material. They can't melt it fast enough. And if you're waiting for the material to melt then the crew isn't working," Irons adds.
If a contractor will be installing long lines, it is probably best to invest in long-line equipment. Smaller equipment - the 1,000- to 1,500-lb. capacity units - is good for lines up to 1½ miles, Hendrickson says. But if you'll be doing lines of one mile or more, the larger long-line trucks are the way to go. Often these trucks have the ability to stripe off both sides as well as apply thermoplastic in all three application methods.
But the most essential piece of equipment is a pre-melting kettle. The pre-melting kettle is used to heat the thermoplastic material to the required temperature before application. Some long-line trucks have an integrated pre-melting kettle. But Hendrickson suggests investing in additional pre-melters to melt the material prior to adding it to a truck's pre-melter kettle. This helps keep the crew and the equipment running at a high production level, he says.
Keep the die system - the container the thermoplastic material flows through to reach the pavement surface - in mind as well. Different sizes of dies are available depending on the mil thickness of the material being applied. Know which size you'll need so you're not purchasing more than necessary or the wrong size. Wehner suggests finding a fully adjustable die that can adjust to multiple mil thicknesses.