Lecture on Anti-Graffiti-Protection Systems

By Dr. Schaum - Research and Development Department of the Company NewPro

1. Introduction The topic of our lecture is:

Outline of the Lectures

The company NewPro - Monheim am Rhein near Duesseldorf, Germany, which I represent develops and markets products for building and construction maintenance for the removal of graffiti stains and preventative protection of surfaces.

We are specialists in surface area protection and maintenance. Graffiti stains, markings or writings, and postering on building facades, monuments, switch or electrical boxes or other fixtures, equipment or furnishings have unfortunately become a serious daily problem. For some it might be a form of art, but for others it is the bone of contention and a real headache.

Graffiti Stains

Despite the large number and variety of different kinds of stains and soiling, the removal of such stains must be fast and comprehensive without serious damage to the building surface. Cleaning without damage to the facade surface and without environmental damage (airway solvent, waterway wastewater components) is difficult to achieve. For this reason the company NewPro developed materials to assist in graffiti removal (partly using bio-degradable components) and additionally graffiti protection system for the surfaces of facades. The proper application of this graffiti protection system first requires exact detailed information about the kind of construction material that the facade is made of.

2. Facades and Surfaces

Properties of the Construction Materials of the Facade Depending on the chemical composition and the building structure the properties of different facades vary significantly. Graffiti protection and the adhesion of graffiti stains depend entirely on the type of construction materials of the facade on which the products are to be applied. While lime, plaster and iron surfaces are relatively volatile to weathering and are easily affected by environmental influences, clinker surfaces, surface-coated construction materials, synthetic materials and glass are not as affected by environmental influences in the short-term. For graffiti protection systems, the chemical reactivity of the surfaces is, therefore, a very important factor. For the adhesion of graffiti systems and graffiti itself, the phase interface area of the surface along with the degree of moistening of the surface area are also decisive. While plastics have a very bad degree of moistening, metal surfaces with primer, for example, are easy to coat. We currently have a lot of experience handling the following surfaces:

Facade Surfaces

We must differentiate between polycrystalline structures (such as metals) and porous structures such as sandstone with many pores. Depending on the type of pores, there are different diffusion processes between different surfaces and deeper areas of the materials. I repeat: The characterization of construction materials is made according to the pore volume and the distribution of the size of the pores. Along with the construction material specific characteristics, the surface finish or roughness of the individual facade surface also plays an important role in understanding the adhesion of the graffiti protection system as well as the removal of graffiti. A graffiti protection system must form a closed film covering over the surface. The more rough or coarse a surface is, the bigger or thicker the amount of coating of the graffiti protection system needs to be. This can have a negative effect on the optical appearance of the object. A change of the refraction angle can cause the shine to diminish, a darkening or also a bath chromatic shift, when compared to an untreated surface. As a General Rule:

• Where graffiti stains have strong adhesion, the protection system also has strong adhesion, for example, natural stone made of sandstone or tuff.
• But, also smooth glass surfaces, which are easy to wet, and zinc coated steel surfaces, have strong graffiti adhesion.

Synthetic material surfaces, for example made of plexiglass (polymethyl methacrylate, polycarbonate, and epoxide bonded material), have a certain solubility concerning organic solvents, which are found in graffiti protection system as well as in lacquers. Synthetic material surfaces can change. If surfaces have a mineral basis coating or a paint coating, the properties of the mineral materials can change. Also wooden doors with and without finishes/coatings have varying ranges of wettability. React different to water? 3. Graffiti Protection Systems Graffiti protection systems are classified according to the individual stability/durability/resistance. Furthermore, whether the graffiti protection system will be removed with a required or routine cleaning or whether it will remain on the surface for further protection. As a general principle, all protection systems involve the application of a separable layer of various levels of resistance/stability to the facade surfaces. This protective layer prevents direct contact of graffiti to the construction material surface. The various systems are distinguished as follows:

• Permanent Systems
• Semi-permanent Systems
• Temporary Systems

Permanent Systems

3. Graffiti Protection Systems

Graffiti protection systems are classified...

3.1 Permanent Systems

This system involves separable layers, which are not affected by cleaning agents and after the removal of graffiti continue to remain effective without renewal. A permanent system consists of several layers, into which the effective layer is integrated. This layer reduces graffiti adhesion and attaches itself to the surface. This deck layer is called the “top coating” and is interconnected with the surface through primer, impregnation or prime coating. This is necessary because “top coatings” cannot achieve a lasting stable bond with the surface and also with porous construction materials; the pores must be closed prior to coating. Otherwise, during drying air bubbles would develop in the protective coating, which could lead to cracks or fracturing. Intensive colors, a shining, or smoothing of an initially rough surface are all signs of permanent systems. Permanent systems are predominantly used on concrete facades. The main permanent layer consists predominantly of polyurethane or epoxy resins. It developes during application as a two component system (polyurethane polyol + diphenylmethandiisocyanate). After the application of the coating onto the facade, the two chemicals react with long-chain polymers, which form a thick coating. A single-component product is also used, which is formed through a chemical reaction. Polymers can also be applied after being dissolved in solvents. With a permanent system, new layers can be applied years later without complication. A disadvantage of this system is the reduced water vapor permeability of the facade walls.

3.2 Semi-Permanent Systems

Semi-permanent systems consist of either a combination of a base coating and a sacrificial layer. The latter is removed together with the graffiti. Alternatively there is a single layer system, in which solvents are applied during graffiti removal or are worn away during graffiti removal. The sacrificial layer must be newly applied, or replaced, after every cleaning. Single layer systems consist of hydrophobic or oleophobic products, which consist of modified oligomer alkoxy siloxane or out of the formulation of siloxane and acrylate. The advantages: They are optically only slightly noticeable and are relatively water vapor permeable. The durability/stability is comparable to that of the permanent systems. Also worthy of consideration are multiple-layer systems, which consist of a combination of impregnation and a sacrificial layer. Acrylates, biopolymers, wax-like bondings or paraffins are applied as an effective separable layer or sacrificial coating. The sacrificial layer makes the removal of graffiti possible without the need for solvent-ingredient products. Increased temperatures allow a removal of the wax and the graffiti.

3.3 Temporary Systems

Temporary systems involve a single-layer system. A chemically uniform product is applied several times. Advantages of the temporary system are that it is optically not noticeable and offers good water vapor permeability. Colored variations of the product are available on the market. The durability and life of this graffiti protection is, however, limited, because simply with water dissolving can set in. Chemicals used for this system include acrylate, metal-cross-linked acrylate, polysaccharide as well as wax-type bonding chemicals. Also thin transparent films, which are applied as a smooth protective surface, are used under this system. With removal of the film, the graffiti is removed. This system has been proven successful for traffic and street signs.

4. Preparation of the Facade Surfaces

The application of the chosen graffiti-protection system demands a certain amount of pre-treatment of the facade surface. Typically the facade surface must be cleaned. It is important to be careful when dealing with monuments because cleaning the surface is an attack to the surface and can cause a change or alteration in the construction material in the immediate surface area. The interaction between the atmosphere and the construction materials can lead to a change in the surface of the material as a result of weathering. Consequently, a cleaning leads to a change in the actual surface. After every cleaning new symptoms of damage arise. It is easy if only dust particles, aerosol deposits etc… must be removed. It becomes more complex if materials can form a firm bond with the surface. In extreme cases there are crusts of several centimeters on the products resulting from air damage, organic materials, and transformation products of building materials. There are, therefore, a large number of ways to clean facades and artificial composite stone. The cleaning methods are distinguished as follows:

• Wet cleaning (water hot or cold, with or without pressure; water + granulate chemicals (acids, base solvents, mixtures))

• Dry cleaning (by hand using brushes, sanding, sharpening, sandblasting)

• Moist cleaning (atomized spraying)

5. Planning - Detailed Work Order - Detailed Estimate - Check

Procedure to RFP (Request for Proposal) for Graffiti Protection Measures

6.Removal of Graffitis

As a general rule, graffiti is difficult to remove from an untreated surface. After the application of a graffiti protection system, the removal is much easier. Even the amount of cleaning chemicals and amount of cleaning water and shot necessary is minimized. There is a chemical and a physical cleaning procedure. For strip painting, for example, a thickened caustic potash is applied to the facade. As a result of this a saponification of the initial bonding in the paint molecules takes place. And, through this, the chemical bonding of the materials in the graffiti substances are destroyed. After this, the surface is rinsed off with water. The time to take effect is between 15 minutes and 1 hour. The washing water is strongly alkaline and is subject to discharge conditions. Organic solvents lead to the source of the bonding agents in the graffiti and, through that, ease their removal. Appropriate solvents include N-Methyl-2-Pyrrolidone, Methylisobutylketone, Turpentine, Butyrolactone, and among other things the MAK values and the biochemical biodegradability of the solvent are to be considered. It is worth mentioning that the need or use of chemicals for unprotected surfaces is 10 times greater than for surfaces, which have been protected with a protection system such as Graffiti Magic. Physical processes are the result of the abrasive effect of mineral particles or of the influence of water vapors or water. For semi-temporary and temporary protective systems, it is recommended that cleaning be effectuated with high-pressure water. Abrasive processes should only be applied to stains which are difficult to remove. Such abrasive cleaning methods can lead to a change in the surface. This is why the entire surface must often be processed or handled. Newer methods for graffiti removal are the Cyro-clean-process, which uses carbonic acid ice pellets. With the vaporization of the carbonic, there is an intense cooling of the surface and a resulting flaking of the adhesives in the graffiti. Another variation is the cleaning method which uses an impulse laser. The energy of the impulse laser leads to a flaking of the smallest particles in the graffiti and to a vaporization of the graffiti. Both methods are still in their development phase and are unfortunately rather expensive to employ.

7. Newer Developments in the Field of Graffiti Protection Systems

Newer developments in the field of graffiti protection systems are coming from the field of nanochemistry - the chemistry of the smallest particles. Products in this field are applied as a coating to glass, stainless steal and other materials. Therefore, it is close to and can be classified as a graffiti protection system. Systems which fall under the heading sol-gel chemistry, are built into our graffiti protection systems and serve as the main component of the coating in the permanent systems (see also NewPro-Nano Stone Plus)From a chemical perspective it deals with flourosilane, or methylsilane, which are applied together in one system to the surface and which align onto the surface during vaporization of the solvent. At the moment, an EU financed research project is being carried out attempting to combine a temporary and permanent system into one system. This system should be applied to monuments. At the trade fair “Paint, Construction and Facades” last week in Cologne, Germany, enamels/gloss paints were introduced with an anti-graffiti coating. These should make it possible to remove graffiti stains more easily and inexpensively. Whether this actually performs what it promises and at which price it can be offered must first be proven in practice. In the graffiti scene there is a new method called "Etching". This method, which applies hydrofluoric acid to etch onto smooth surfaces such as glass, is extremely dangerous. Hydrofluoric acid is both strongly caustic and poisonous (see Ordinance on Hazardous Substances). It puts anyone in danger comeing into contact with it, not only the sprayer/graffiti artist him/ herself, but also the cleaning personnel and innocent bystanders. Bus stops and train stops for public transportation are often goals of the "Etching-Scene". Due to the great health risks from contact or moisturizing of the corresponding etching stains which exist for the cleaning personnel, only specially trained qualified personnel should clean these surfaces. A 1-Euro jobber/social welfare recipient workers, hired to clean the local community and clean off graffiti stains are completely unqualified to handle such tasks. Only specialists with protective clothing (acid-proof gloves and protective goggles for wet cleaning) should be employed for cleaning such etching graffiti. In the Ruhrgebiet, in Berlin and also in the regional centers such as Saarbruecken, this problem has been encountered more often recently. The products by Graffiti Magic are examples for cost-effective graffiti protection. They come in matt version or Poster Magic as a gloss version and are offered by the company NewPro for long-lasting protection. A building object at Ravensbergerstrasse 36 in Bielefeld, Germany was coated with a protective coating and survived several graffiti attacks undamaged (without any new coatings). An advantage of our long-lasting system is that graffiti can be removed simply using warm soapy water in 85% of the cases without any additional removers or chemicals. Our special remover is then applied to the other 15% of the cases. A new coating, however, must not be applied. A further advantage of our permanent system is that posters do not stick to surfaces coated with Graffiti Magic or Poster Magic. Our systems have been on the market for more than 10 years. The most recent reference object is the new Wembley Stadium in London. The “Spanish Steps” in the new stadium will be protected against graffiti attack with Graffiti Magic Matt. Alternatively, we have a sacrificial layer system in our product line such as, for example, NewPro-GS 207 Graffiti Protection System for absorbent stone surfaces, NewPro-GS 206 Graffiti Protection System for synthetic materials and metal surfaces and Graffiti Protection GS 204 for marble and granite. Certainly there are other protective systems, which are presented here. But, first an evaluated application by specialists from an authorized specialist service center in order to determine the proper or most effective graffiti protection system. Graffiti Magic and Poster Magic as permanent systems as well as our NewPro sacrificial layer system for the graffiti protection can be helpful to make the initial decision.