The reasons for the appearance of pinholes and bubbles on the surface of thermoplastic road marking lines

The pavement was not fully dried during construction, or there was residual moisture after rain, which was instantly heated by the high-temperature coating (about 180-220℃), causing the moisture to rapidly vaporize and form bubbles. The top of the bubbles broke the un-solidified coating, leaving this kind of pinhole-like defect.

Especially in environments with low temperatures and morning dew, this is more likely to occur.

The coating itself was damp (such as improper storage or long-term exposure after opening), or the fillers (calcium powder, etc.) in the formula had excessive moisture content. After melting, the moisture turned into water vapor, forming bubbles and pinholes before the marking was solidified.

High temperature: The coating was too thin and had good leveling properties, causing the bubbles to easily float to the top and break the surface, forming dense small holes.

Low temperature: The coating had too high viscosity, preventing the bubbles from being smoothly discharged and being trapped inside, and they would be broken by the surface when heated later.

Resin residual solvents, low-molecular-weight additives / Waxes volatilized prematurely at high temperatures, generating gas; or the coating was stored for too long and the additives failed, resulting in continuous gas production during the melting process.

The asphalt pavement itself has fine pores and cracks. The air inside was heated and expanded, also breaking the un-dried coating, forming pinholes.