What temperature is road paint?

Mar. 07, 2024

Every year, our maintenance crews spend the dryer summer months re-striping thousands of miles of highway around the state. This work is necessary to keep striping visible and reflective at night, as it does wear out over time.

Highway paint is special in that it has tiny little glass beads mixed into it, which is what makes it reflective at night. Similar methods are used for highway signs and license plates. When the beads are hit by headlights, they reflect some of the light back towards the driver, making the paint more visible. The glass beads are made from 100% recycled glass.

Re-striping work is seasonal, as the roadway must be dry and at least 50 degrees to apply the paint. Fortunately, the paint is quick drying, and will be dry in anywhere from 30 seconds to five minutes, depending on conditions at the time of application. Striping season typically runs from the beginning of April to the end of October.

How you can help

We know that re-striping is an inconvenience to drivers while we are doing it, but we need your help to get it done as quickly and effectively as possible:

Watch for "wet paint" warning signs and warning trucks.
Listen and look for traffic reports with information about where and when striping crews will be working.
Don't drive across the wet paint. We normally have a follower vehicle that will give you an idea of where the paint is still wet.
Keep the distance from the paint truck (or follower vehicle) marked on the sign. This helps to both avoid driving through wet paint and reduce the risk of paint getting on your vehicle.

We do our best to warn drivers about wet paint and keep them out of it. Driving through the wet paint results in the paint sticking to your tire(s) instead of the road, including the reflective glass beads, making the striping less effective and a mess on both the road and your tire. Driving through the wet paint or too close to the paint truck may also result in paint getting on your vehicle.

Should you get paint on your vehicle, you may have about an hour to get the paint sprayed off with a high pressure hose, but sooner is more likely to be successful. The paint is water-based, but it is designed to last under harsh conditions, so once it sets it is nearly impossible to remove. If paint gets on your vehicle when warning signs are present, the state will deny the reimbursement claim.

Thermoplastic road marking paint, also called hot melt marking paint, is a kind of powder paint. When applied as road surface markings, a hot melt kettle is used to heat it to 200 °C (392 °F) to melt the powder, after which it is sprayed on the road surface. After cooling, the paint forms a thick polymer layer, which is wear-resistant, bright, and reflective. In recent years, practical applications tests have proved that the marking lines lack surface roughness and can easily cause wheel slip, resulting in a traffic accident in snow and rainy weather. Therefore, some countries once restricted the use of this paint or demand the use of anti-skid particles. In order to increase the antiskid performance of the line, thermoplastic paint has added reflective glass beads and other coarse fillers. Thermoplastic can be used very effectively for large anti-skid areas on roads and pedestrian walkways by adding glass beads. It can be produced in any colour and is suitable for car parks, factory walkways, and many other areas. It hardens quickly and can be driven over after just a few minutes.

Components
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Thermoplastic marking paint consists of synthetic (polymeric or non-polymeric) resin, glass beads, pigments, fillers (fine like calcium carbonate and coarse like sand), packing materials, additives, etc.

Synthetic resin has thermoplasticity, make the hot melt coating fast-dry and strongly adhesive to the road surface. Non-polymeric resins, based on colophony, are also widely used.
Additives in the paint can increase the plasticity of the coating, and make it resistant to subsidence, pollution and color fading.
Pigments: the common colours of road lines are yellow and white. White pigment is titanium dioxide. Occasionally zinc oxide can be used, but it is less effective due to low refractive index. For yellow thermoplastics, organic pigments (like Pigment Yellow 65, 74 or 83) are mostly used; lead-containing pigments are obsolete and banned in essentially all developed countries.[citation needed
] Thermoplastic road markings can also be formulated in other colours.
Packing materials, as filling added into the paint, ensure mechanical strength, wear resistance, and color of paint coating. The particle size will affect liquidity and precipitation, as well as the surface processing.
Glass microspheres are added in order to improve the identification of lines at night, to improve the brightness and durability of the marking. Glass beads, usually 0.1-1.4 mm in diameter, are colourless and transparent; they reflect light from vehicle's headlights back toward the driver and foremost protect the road marking from abrasion.

Matched machines
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A road marking machine is a machine specially used to mark different traffic lines on road surface, and some can remark on old lines directly. It can screed, extrude, or spray processed road paint onto the road surface to form durable coating lines. A hot melt kettle is used for continuously heating, melting, and stirring thermoplastic marking paints, preparing molten paints for the thermoplastic machine, especially for long-distance road-line-marking work. The molten paint quality can affect the line quality greatly.

Microplastic pollution
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Thermoplastic paints, when used as road markings, are a source of microplastic pollution. Abrasive wear of road marking paint resins has been claimed to be responsible for 7% of all microplastic pollution, with estimates ranging from 0.7% to 19%.[1]