What is paint overspray?
Paint overspray refers to the fine particles of paint that settle on surfaces outside the intended target area during a painting project.
This can occur during automotive painting, building or structure painting, and in various industrial and manufacturing processes where spray paint or other coatings are used.
Overspray happens when paint particles are carried by the air to land on nearby cars or other unintended surfaces. These particles can adhere to the car's surfaces, creating a rough, textured layer that can detract from the appearance and while few coatings can cause damage to the surfaces of the car, incorrect methods of removal can potentially cause damage.
Common Types of Overspray Contamination
Generally, when people think of paint overspray, they think of car paint, which is still one of the most common type of contamination we get enquiries about, and is usually the most easy to remove. However, we also see contamination from a wide range of paint, varnishes, stains and coatings which can be far more challenging to deal with.
Bodyshop and Smart Repair Overspray
As I write this, there happens to be a smart repair technician spraying the bumper of a neighbour's car. While he has carefully masked up the car he is working on with plastic sheeting, it's a windy day and no other car in the street is protected. You can see the potential problem.
There is little doubt that overspray will contaminate nearby cars, and depending on the type of paint used, the temperature and a host of other factors, this may or may not be a problem.
If the paint overspray dries before it falls on another car, it may just fall as dust. If the car it lands on is dirty and already covered in dust and traffic film, then it's fairly likely it will just wash off when the car is next cleaned.
Conversely, if the paint falls on a clean car, there is the possibility for it to bond to the paint. Depending on how wet it is when it hits the car, it can be fairly straightforward to remove, either with a clay-bar, solvents or a combination of both.
Fence Paint, Stains and Treatments
Thankfully, coal tar creosote is now banned in the UK, however, the non-carcinogenic products which replace it behave relatively similar when they got on a car's paintwork. They can leave an orange stain as the product can soak into the microscopic pores of unprotected paintwork, which can be removed by polishing out.
These wood treatments are particularly likely to cause problems because they are stains which are thin and stay wet. There is a high chance of causing splatter when brushing them on, but many of the main brands, such as Ronseal and Cuprinol now supply their products in a sprayer.
Red Oxide and Etch Primers
Red oxide primers contain iron oxide which is essentially rust, while etch primers contain phosphoric acid to etch metal surfaces to create a key for the single pack resin to bond to. These paints are often used to paint railings, fence posts, lampposts and Rolled Steel Joist used as building frames.
Epoxy Resin and Hammerite
These paints are often designed to paint outdoor metals such as lampposts and railings and are highly resistant to corrosion and chemicals. Epoxy resin paints are used as floor paint and increasingly to paint concrete and stone and are particularly hard-wearing. This can make them particularly challenging to remove, as they are resistant to solvents.
Bitumen Paint
Bitumen paint is made of coal-tar and oils and has many applications, such as undersealing cars, protecting wood and sealing roofs. While it is falling out of favour to be replaced by epoxy resin-based coatings, it is still widely in use.
Road Line and Marking Paint
There are various methods for marking road lines, but it is seldom sprayed as most of it is designed to go on very thick. However, if run over while still wet, it can splatter up the side of the car. Designed to be incredibly durable, it requires special solvents to remove it.
Spills and Vandalism
Deliberate acts of vandalism might involve spray tagging slogans over a car with a rattle can or pouring whole tins of paint over a car, in which case the paint involved could be anything from emulsion to enamel. Likewise, running over paint spilt on a road could be any kind of paint, varnish or stain, and some investigation had to be done to find the best method of removal.
Written by Danny Argent. Last updated 01/03/2024 12:00