Graffiti removal as soon as possible!

A study published in the Handelsblatt showed: If a graffiti is removed within 48 hours, the risk of a further spraying is 0-10%. Waiting one year with the removal means risking a follow-up act with nearly 100% certainty according to a study.

• Therefore, remove graffiti immediately to deter follow-up offenders!
• In addition, fresh graffiti is much faster and easier to remove than old graffiti.

Definition

Graffiti is a collective term for privately applied pictures or writings on surfaces of the public space.

Problems caused by graffiti

Graffiti significantly affects the image of the affected building.

• Graffiti leads outsiders to draw conclusions about the social environment of the affected object
• Graffiti have a negative influence on the building's physical balance
• Graffiti lead to structural damage

Graffiti and substrates from a chemical point of view

• Today, graffiti and paint smearings are usually created by highly solvent-based spray paints or "crayons" on all substrates. Spray paints basically consist of the components:
• color pigment, dyes
• binders such as alkyd resins, acrylic resins, silicone resins and acrylates
• additives such as metal flakes to achieve metallic effect
• Solvents

Fiber pens usually contain:

• Aqueous solutions of basic or acidic dyes.
• Binders
• Additives such as glycerine as a moisture retainer
• Solvents that are hazardous to health, e.g. xylene and toluene

The removal of graffiti from facades is particularly problematic because:

• the surface of facades is usually highly structured
• facade materials (plaster, natural stone facing, etc.) absorb the graffiti to a depth of several millimeters
• facade materials have only low mechanical strength and are often highly sensitive to solvents (polystyrene - thermal insulation!).
• The solvents of the spray paints bind directly with the synthetic resin components and are irreversibly incorporated.

Damage caused by graffiti

On unprotected surfaces graffiti damages twice:

1. Optical
2. damage to the building fabric

• By penetration of spray paints and markers. Binders and plastic components in plasters and paints can dissolve.
• In the case of full thermal insulation systems based on polystyrene, the insulation boards are destroyed
• Restriction of diffusion capacity - leads to consequential damage such as cracks, frost damage, detachment of plasters and paints as well as scaling and sanding of natural stones (sandstones)

Graffiti removal, unprotected substrates:

On unprotected substrates, graffiti removal is always a case for the specialist. Many methods and products exist, but usually an interaction of all components is required to remove a graffiti cleanly.

• Goal: shadow-free removal without damaging the substrate.

Graffiti removal thermal

Laser cleaning

• Only used for the preservation of historical monuments

Dry method

• Has not proven itself, too expensive and very noisy

Hot water/steam

• Only in combination with chemicals

Painting over graffiti:

• In many cases, graffiti is painted over on surfaces that were not originally painted (exposed concrete, sandstone) without removing the spray.
• This practice is extremely questionable from both a building ethics and a building physics perspective.

Graffiti removal, practical experience:

The best results in graffiti removal are achieved with the physical chemical process in combination with hot water high pressure. The reason is that a chemical reaction takes place between the individual products, which removes the graffiti from the surface instead of driving it further into the substance as with conventional solvents.

• Abrasive cleaning often leaves irreversible damage - in many cases, this can only be covered up by "cosmetics".
• "The miracle cure" does not exist!
• A 100% success is not always possible or a question of effort and return.
• Experience is decisive for success in cleaning because since each paint smear represents a new challenge and may require different cleaning methods.
• Always create sample surfaces, because only the object shows which method can be used to effectively remove the paint smear.
• Temperature (exterior and surface) is decisive for the effect – the warmer the better.

Graffiti removal cleaning procedures:

1. assessment of the substrate:

• Mineral, non-mineral
• Absorbent, non-absorbent, open-pored, soft or hard
• Painted, unpainted, varnished, powdered
  
  

2. assessment of the graffiti:

• Spray (acrylic, nitro, 2K, etc.)
• Fiber pens (permanent, water soluble)
• Bituminous

3. size of the graffiti

4. create sample areas.

Under no circumstances should you:

Work with conventional solvents. Graffiti penetrates deeper into the substrate.

• Use products containing CHCs (To be avoided for environmental, health and water protection reasons).

• Use products containing acids. (attack substrate, e.g. removal of cement skin on concrete).

• Remove bituminous sprays with conventional graffiti removers. (Graffiti penetrates deeper into the substrate).

• Use residual shadow removal on highly absorbent substrates (never on sandstone!, leads to irreversible damage).