How to apply thermoplastic road markings
The whole question of how to apply thermoplastic road marking presupposes that the person considering this, if he is not engaged in a purely academic enquiry, is possessed of sufficient financial and technological capacity to undertake the task.
Plastic is an organic material and originates in tiny marine animals and plants that got embedded deep in the structure of the Earth and, over literally millions of years, changed into a black viscous liquid ("black gold") that powers most of humankind in this age.
In this way plastic is related to coal which is the fossilised rock originating in carboniferous forests from ages ago.
The plastics industry is based on what can be adapted from these sources and is highly important for development.
The key point about thermoplastic road marking is that the plastic becomes viscous and fluid above a certain temperature, usually around the 200 Celsius point.
There is a huge amount of literature about thermoplastics most of which is outside the scope of this article.
The malleability of plastic at high temperature coupled to its fixed form after cooling makes it a suitable material for road marking. It has a greater durability than most or all kinds of paint and usually lasts for at least several years even in heavy use conditions.
The large-scale application of thermoplastic line marking is outside the scope of this article. Let it suffice that this is a major industry with specially designed trucks and storing and feeding and shaping apparatuses.
In the humble matter of manually road marking roadways, essentially, the material is literally rolled over the road surface and, usually, heat is applied manually with a heat torch.
There are exactly three methods of attaching plastic to the road:
- Overlay
- Inlay
- Preformed thermoplastic
In the overlay mode the roll of plastic is laid over the road surface and then "industrial grade" rubber cement bonds it to the pavement. This usually lasts about 36 months and it is vulnerable to snow ploughs and salt.
In the inlay mode, while the road surface is still hot from the building process, the tape is applied over the surface and rollers mould the two together.
The preformed thermoplastic mode consists of laying patterned plastic over the road with legends such as "BUS STOP" and a worker uses a propane heat torch to melt the plastic. These are often seen at intersections.
Some readers might be interested to know that epoxy is tipped to become a possible future replacement for thermoplastic in the matter of road marking.
