Effective graffiti removal

Daniel Took, Head of Professional Product Marketing at Kärcher UK, explains some of the most effective ways businesses can tackle graffiti and leave surfaces looking like new.

Graffiti is an increasing problem for many towns and cities, but luckily the technology for its removal has advanced in recent years, making it more effective. There are four key methods that can be used to leave surfaces looking like new:

Particle blasting

Best used for gentle graffiti removal, these blasters use air flow (compressor with a minimum output of 4m³ per minute) alongside dosed spray agents to effectively remove the stubborn dirt. By selecting the appropriate type and quantity of spray agent and air pressure, the procedure can be adapted for different surfaces.

There are around 2000 types of spray agent available on the market, ranging from blast furnace slag to chalk, glass powder, or even calcium carbonate. The differences aren’t just down to the output materials used, but also the size, shape and hardness of the grain. Dust is largely prevented by adding water at the nozzle (‘damp blasting‘) which has the added benefit of binding the spray agent and removed pigments in the water.

Injector blasting

These systems have proven to be extremely flexible, easily transported in a case, and have short set-up times, making them particularly effective. All parameters – air flow, air pressure, water flow and spray agent volume – can be set by the operator on the trigger gun, according to the level of dirt and surface being cleaned. The operator can quickly switch the spray agent type being used, from very gentle to very abrasive.

Injector blasting offers the advantages of easy transport and short set-up times, high adaptability, versatility, being environmentally friendly, with low operating and investment costs, as well as safe handling.

High-pressure cleaning

High-pressure cleaners are a popular choice with hot and cold washers, allowing users to remove dirt effectively. There’s a growing trend towards hot water pressure washers as the higher temperature makes lighter graffiti easy to remove. Hot water machines can also reduce cleaning time up to 40%, whilst less cleaning agent is required (sometimes none at all). Drying times are also reduced so that next steps can get underway quicker.

Water flow is an important factor when it comes to selecting which high-pressure machine to use, as it’s crucial for impact pressure, which generates the cleaning action and aids the removal of the dislodged dirt. The type


of nozzle, spray angle (a 25° nozzle is normally used) and spray distance are also extremely important.

Dry ice blasting

A gentle and effective cleaning method that has a wide range of uses, including grease, oils, adhesives, binders and silicone. It’s also non-corrosive and virtually non- abrasive, which means it can be used on sensitive surfaces. Dry ice blasting is recommended when other cleaning procedures are prohibited by legal regulations, or if these methods would not be successful or could only be used with considerable investment of time and at great expense. However, this method requires consideration, as the technology is costlier.

Dry ice particles are ejected from the trigger gun with a compressed airstream up to the speed of sound and sublimate immediately upon contact with the surface being treated.

They take effect in three main ways:

• Ejected particles release kinetic energy upon impact. • The layer being removed cools suddenly upon contact with the –79 °C ice, becomes brittle and cracks.

• Some frozen carbon dioxide penetrates the cracks of the encrusted dirt and paint layers and sublimates, increasing its volume by a factor of 400, causing the dirt to split off completely at a microscopic level.

The dirt is dislodged without the use of high pressure or water and falls off the surface. As the dry ice turns into a gas upon impact, no residues are left.

When selecting which method to use, it’s key to consider the surface material the graffiti needs to be removed from to ensure the removal is effective and doesn’t cause damage to the surface itself.

Page 1  |  Page 2  |  Page 3  |  Page 4  |  Page 5  |  Page 6  |  Page 7  |  Page 8  |  Page 9  |  Page 10  |  Page 11  |  Page 12  |  Page 13  |  Page 14  |  Page 15  |  Page 16  |  Page 17  |  Page 18  |  Page 19  |  Page 20  |  Page 21  |  Page 22  |  Page 23  |  Page 24  |  Page 25  |  Page 26  |  Page 27  |  Page 28  |  Page 29  |  Page 30  |  Page 31  |  Page 32  |  Page 33  |  Page 34  |  Page 35  |  Page 36  |  Page 37  |  Page 38  |  Page 39  |  Page 40  |  Page 41  |  Page 42  |  Page 43  |  Page 44  |  Page 45  |  Page 46  |  Page 47  |  Page 48  |  Page 49  |  Page 50  |  Page 51  |  Page 52  |  Page 53  |  Page 54  |  Page 55  |  Page 56  |  Page 57  |  Page 58  |  Page 59  |  Page 60  |  Page 61  |  Page 62  |  Page 63  |  Page 64  |  Page 65  |  Page 66  |  Page 67  |  Page 68  |  Page 69  |  Page 70  |  Page 71  |  Page 72  |  Page 73  |  Page 74  |  Page 75  |  Page 76