2025 Road Hot Melt Coating Construction Technical Guidelines

This construction guide is only applicable to hot-melt reflective marking coatings with qualified flowability as specified in JT/T280-2025 edition of “Road Marking Coatings”. As long as all necessary conditions are met, including qualified coatings and the temperature of the road surface, moisture free road surface, minimum marking thickness, etc., the use of hot-melt reflective marking coatings can achieve excellent performance. The typical service life range is 4 to 8 years (depending on road usage conditions).

The correct application of hot melt coatings:

1. Temperature is the most important factor for the proper mixing, melting, and bonding of hot-melt coatings. Heat the coating in the hot melt kettle to a temperature between 205 ° C and 225 ° C, and stir appropriately to turn the hot melt coating into a uniform liquid. At this temperature, the hot melt coating melts onto the upper surface of the asphalt pavement, forming a thermal bond. When applied on porous surfaces, such as open graded asphalt or grooved concrete, the hot liquid hot melt coating fills all gaps and forms a good mechanical lock on the concrete.
2. The thickness of the hot-melt marking applied should comply with the regulations. A minimum thickness of 2.28mm is crucial for maintaining good adhesion of the material. The thermal bonding that occurs when applied at the appropriate thickness ensures the durability and long-term anti reflection of the hot-melt coating.
3. The markings are raised above the road surface, and the reflection generated by glass beads makes the hot-melt coating easier to see from a distance and at night. This thickness also helps improve the anti reflection performance under humid conditions and the excellent durability of the product.
4. The quantity of glass beads, whether pre mixed with paint or spread on the surface, must be correct. The surface bead must be evenly spread, with an adhesion depth of 50% to 60% of the diameter of the glass bead. Spread in an area of 4 to 6 kilograms per 10 square meters. Appropriate application thickness, appropriate melting temperature, and correct glass bead coating ensure accurate settlement depth of glass beads. Pre mixed beads should be mixed in hot melt coatings according to design specifications.

Equipment: Application devices should comply with the standard specifications. Before the start of the project, the engineer may be responsible for approving such equipment, whether it is mobile or portable.
The melting kettle must be able to uniformly heat the thermoplastic material to its application temperature without burning it. Keep the temperature above 205 ℃. The heating device of the hot melt kettle should use a heat transfer medium composed of thermal oil or hot air. The thermometer must be visible outside the hot melt kettle to indicate the temperature of the hot melt coating. Do not confuse the paint temperature gauge with the heat transfer medium (oil temperature) gauge. External calibrated thermometers should be used to frequently monitor material temperature. When applying, the appropriate application temperature should always be checked.
Mixing and mixing equipment – hot melt kettle and portable marking machine: ● Material mixer must be equipped. It must be able to thoroughly mix the coating at a certain speed to ensure uniform distribution and temperature uniformity of various materials inside the coating.

Primer spraying: Before using hot melt materials, the primer material should be sprayed onto the road surface at a specific speed recommended by the primer/sealant material manufacturer. All primer coating equipment should be inspected to ensure that it is fully operational and capable of spraying primer/sealant at the specified speed.
Glass bead spreader: Both mobile and portable hot melt coating equipment require a falling or pneumatic glass bead spreader. After marking, immediately sprinkle the glass beads evenly on the hot melt marking, embed them into the marking, and fix them at a depth of 50-60%. The purpose of glass beads is to provide initial nighttime reflectivity for road markings. Without glass beads, drivers would hardly be able to see the road markings. The glass bead spreader should be checked regularly to ensure the correct amount of spreading and to ensure that the speed of each application on the entire marking surface is consistent.
Marking equipment: Marking equipment can be roughly divided into three types: extrusion type, spray type, and scraping type. The device should be placed in a windproof location. The extrusion type marking bucket is heated and suspended above the road surface, using hot melt paint with forced extrusion and distinct contours for marking. Spray equipment – Hot melt spray patterns should produce stripes of uniform thickness, distinct contours, and firm adhesion as specified. When mixed with molten hot melt coatings, compressed air must be dry. Ironing and Pressing Equipment – The marking bucket rides directly on the road surface, and the continuous line is formed by three sided molds. The control door is set to a predetermined thickness (most domestic push type scraping and marking vehicles).

Marking: As the failure of coating adhesion is related to construction, it can be minimized through appropriate construction control. This can be achieved through proper and frequent inspections at the project site. The following guidelines aim to ensure successful application performance.
Marking location – In order to minimize damage caused by snow plow blade and base failures, thermoplastic markings must be placed directly on the lane, preferably 2 inches away from the shoulder and construction joints. Do not use edge line markings directly on the joints formed between the road and adjacent shoulders. Do not use vibration markings on longitudinal joints between lanes.
Equipment – Equipment should be inspected daily to ensure its operability and compliance with regulatory requirements. Malfunctions of daytime equipment may result in prolonged storage time or excessive heating of hot-melt coatings or primers after application. This may result in some work not meeting the overall quality and lifespan requirements of road sign materials. Intermittent equipment malfunctions may also result in inconsistent performance of a small portion of lane markings within a limited area. The continuous and consistent operation of all equipment used for manufacturing hot-melt coating applications is extremely important. Keep the equipment clean and free from material residue accumulation.
Paint – Paint specifications should be thoroughly reviewed. The function of government testing laboratories is to determine whether coatings meet the requirements of coating specifications. The project engineer may retain on-site samples of materials for quality verification.
The paint packaging should have accurate batch number names. The packaging should clearly display the type of coating and formula resin: 1) extruded or sprayed. 2) Petroleum resin or rosin resin;

Although petroleum resin and rosin resin coatings may blend together on the road, they are incompatible in the melting pot. Failure to thoroughly clean the hot melt kettle during the coating conversion process can lead to serious equipment problems (note: automated marking equipment is generally used more often). Do not mix petroleum resin and rosin resin coatings!!!
Road surface – The road surface must be clean, dust-free, and dry. Remove existing poorly adhered markings and curing agents. The air and road surface temperature should be at least 10 ℃, and the temperature should continue to rise during the construction process. The large amount of sediment on existing painted road markings, polymer traffic markings, and accumulated dust on the roadside all need to be removed. In some cases, air spraying or manual or mechanical cleaning is sufficient to clean the surface. In other cases, more effort or different methods are required, such as sandblasting, water spraying, or mechanical cleaning. The new hot melt coating application should successfully adhere to the worn existing hot melt coating markings or pre formed hot melt coating markings. Do not use hot melt paint on existing pre formed markings.
All road surfaces should be noticeably dry. Moisture is the most harmful factor affecting the bonding strength of markings. The underground moisture content is sufficient to affect proper bonding. Dew and fog in the early morning usually cause moisture. If there is too much moisture on the road surface, it usually leads to blistering of the hot applied markings. Bubbles will form as surface bubbles and may or may not rupture. They are easy to detect, and if this happens, the marking operation should be stopped until the road surface becomes dry. The only way to determine the presence of moisture is through testing. There are many methods to test moisture.
Use tape to stick a 12 inch square thin plastic sheet onto the road surface, carefully sealing all edges. After 15 minutes, check the bottom of the board and the road surface. If there is too much moisture, do not use hot melt coatings. Place an 18 inch tar paper on the road surface and apply a hot melt coating heated to 215 degrees on top. Wait for two minutes and pick up the oiled paper. Check the bottom surface. If there is moisture, do not apply.
Air temperature – Hot melt coatings should only be used when the air temperature reaches 10 ℃ and is still rising. We must consider the factors of wind and cold. If the temperature drops below 10 ℃, the scratching operation should be stopped.

Primer application – Use the primer recommended by the hot melt coating manufacturer: ● On all concrete ● Asphalt surfaces exposed to oxidation and/or aggregates for more than two years. If specified before applying the hot melt coating, the primer must be sprayed on all road surfaces in the amount recommended by the manufacturer. Before applying hot melt coatings, they must solidify within the specified curing or evaporation time.
The road surface that has been coated with primer must be marked within the specified time or on the same working day. If the surface that has been coated with primer does not have markings applied within these time limits, the primer must be reapplied according to the manufacturer’s specified ratio before applying the hot-melt coating. If approval is obtained for the use of epoxy primer, the mixing ratio must be checked and hot melt coating application must be carried out before the epoxy resin is cured.
Improper application of primer/sealant can lead to adhesive failure between hot-melt coatings and substrates. Incorrect application may also lead to physical degradation of thermoplastic materials, such as excessive pinholes and foaming of the circuit. This degradation may occur by dissolving the adhesive in the solvent system contained in the primer/sealant, and improper drying time and dosage can lead to a decrease in the adhesion and detachment of the coating and road surface.
Hot melt coating application – Hot melt coatings must be applied to the road surface within a temperature range of 205 ℃ to 225 ℃ (depending on the surrounding weather conditions). It is best to measure the temperature of the coating at the contact point of the road.
After marking the hot-melt coating, glass beads must be immediately sprinkled on the mechanical surface. If the glass beads do not adhere to the hot-melt coating marking, all operations should be immediately suspended until the problem is resolved. When the glass beads are embedded at 50-60%, the anchoring strength and reflection effect of the glass beads are optimal.
The application of hot melt coatings at an appropriate application temperature (205 ℃+) is the most critical factor affecting adhesion to the substrate. If the road surface temperature is 10 ℃, the recommended temperature for hot melt coating is 225 ℃. If the road surface temperature is 25 ℃, hot melt coatings can be used at lower temperatures.
The application on the surface of cement should always exceed 218 ℃ to maximize penetration and improve bond strength.
Non contact infrared thermometers can be used to check the temperature of hot melt coatings in hot melt kettles, applicators, or outlet distribution devices.
A difference of 2 ℃ is acceptable, but if it appears to be 2 ℃ below the recommended minimum application temperature, then a difference of 2 ℃ is not acceptable (foreign automatic temperature control systems such as thermal oil).

Hot melt kettle operation ● Regularly calibrate the paint melting thermometer using a reference thermometer (recommended once a week) ● Fill the paint to 30% of the capacity of the hot melt kettle. When the hot melt coating liquefies, gradually add the remaining material to fill the hot melt kettle. Transfer the hot melt coating 30 minutes after the temperature reaches 205 ℃. During the transfer process, the hot melt coating should be filtered through a quarter inch sieve. When two-thirds of the liquefied paint is used, add more hot-melt paint. After reaching 205 ℃ for 30 minutes, the material is ready for transfer again. After the temperature of the hot melt coating cools to 150 ℃, stop stirring. Caution ● Maximum holding time: Do not keep the hot melt coating above 205 ℃ for more than six hours. ● Maximum temperature: Hot melt coatings should not exceed 232 ℃. Maximum reheating: Heat the melted hot-melt coating up to three times. The color change indicates that the material is overheated and starting to burn: the white hot melt coating turns beige or cream colored; Yellow appears brown or green. ● Cleaning: If there are burnt or charred particles remaining on the sieve during the feeding process, please arrange for cleaning. When converting from petroleum resin to rosin resin, thoroughly flush the system, and vice versa. ● Operation tip: Do not completely empty the paint in the melting tank of the hot melt kettle during the night closing process unless it is necessary to replace the material. Keep the hot melt feeding cylinder closed to prevent moisture and other contaminants. ● Precautions: Prevent temperature loss during the feeding process. ● Safety reminder: During use, place a bucket of ice water on site. If accidentally exposed to hot melt paint, immediately cool the affected area with ice water. Follow the instructions on the Material Safety Data Sheet or immediately call a doctor.

Marking thickness: The specified thickness of petroleum resin or rosin resin hot-melt marking can be between 0.8 and 3.2mm without surface beads. The service life of hot-melt marking is directly related to its thickness. Thin coated lines will wear out faster than thick coated lines. To ensure the use of appropriate thickness, routine checks can be conducted on the thickness of the markings.
Throughout the entire work process, the thickness of the hot melt coating should be uniform and consistent. The overall difference in coating rate and total thickness of hot-melt coating will affect the durability and performance of the marking. Appearance: The overall process of marking the hot-melt coating used should be continuously inspected. The marking should have a specified width and neat edges. White, yellow, red, black, and other colors should be clearly visible. Glass beads should be evenly distributed on the entire marked surface. Hardened hot melt coatings should be able to resist deformation, dust, etc. Traffic will be opened within 2 to 10 minutes after the application of the plan (depending on the ground temperature). The marking should be firmly adhered to the road surface. If the hot melt marking can be easily removed from the road surface using a putty knife, and there is little or no asphalt base on the back of the marking, it can be considered that the base does not have sufficient adhesion. It must be integrated with asphalt pavement to ensure maximum mechanical bonding strength. The bond strength of concrete can be checked by forcibly separating it with a hard putty knife.

Construction inspection of road surface: The surface is clean and dry. Damaged existing markings or cured compounds have been removed. (Note: Do not use hot melt coatings on existing tape products.) ● Cement or asphalt that has been used for more than two years, oxidized, and/or exposed to aggregates should be coated with primer according to the recommendations of the hot melt coating manufacturer.
Temperature ● Surface 10 ℃, still rising ● Air and surface temperatures are at least 10 ℃, and still rising. The hot melt coating has been heated to at least 205 ℃ and not higher than 232 ℃, with a heating time not exceeding 6 hours.
Materials/Equipment ● Verify material product certification (hot melt coatings, glass beads, and primers/sealants, if required). Extract material samples according to your institution’s sampling and testing procedures. Inspect the contractor’s equipment according to the contract requirements. During the application process, check:
Noodle bead application: The beads settle to a depth of 50% to 60% of the bead diameter. Unless technically impractical, machine bead spreading should be used. ● Correct bonding of materials
Process: The appearance of the markings is consistent, and the straightness meets the specifications. The cutting of the marking end is clean. There should not be excessive spraying.

This construction guide for hot-melt reflective marking coatings is only applicable to JT/T280-2025 version of hot-melt reflective marking coatings. Other standard coatings can be used as a reference.

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