Removing Graffiti from Historic Masonry (Part D)
Most of the chemicals used for graffiti removal are dangerous to workers, as well as to others who may be in the vicinity. Organic solvents are toxic by ingestion, inhalation, and skin contact. Material Safety Data Sheets(MSDS), available from the product manufacturer for all paint-removal products,should always be consulted and followed. Identification of hazardous components and checking with chemical reference works will help assure that the least hazardous, but most effective, products are selected.
Generally speaking, it is a sensible policy to carry out all graffiti removal in well-ventilated conditions. Some solvents can be used only outdoors,and sometimes forced ventilation may be necessary even there, requiring workers to use air-fed respiratory equipment to avoid wind-blown fumes.Smoking, eating or drinking must not be allowed when cleaning is in progress.
Some materials used for graffiti removal are so corrosive that accidental contact can cause serious, permanent scarring and painful injuries. Wearing appropriate protective clothing must be strictly enforced. Mandatory personal protective equipment (PPE) normally includes face shields or safety glasses;long, chemical-resistant gloves; face masks with respirators for organic solvents; and possibly, full protective clothing with an independent airsupply.
All smoking and open flames should be rigorously excluded from work areas; many solvents are flammable or highly explosive in vapor or liquidform when mixed with air. Solvent residue, used swabs, cloths, overallsand all other solvent-contaminated items should be safely and legally disposedof, or properly stored-even overnight-away from potential sources of fire. Electrical equipment may require explosion-proof fittings when used with certain solvents.
When electric pumps and pressure-spraying equipment are used, it is especially important that all necessary precautions be taken to avoid electricshock. Water sprays and puddles on the ground present a potentially dangerous situation, if they come into contact with temporary wiring at worksites where graffiti is being removed. Such hazards must be carefully monitored and controlled.
As with any construction project, attention should always be directed toward the general safety of the workers and passers-by, but also toward possible damage to the resource itself that might result from careless placement of ladders, or scaffolding. Chemicals used for masonry cleaning can also damage adjacent metals, glass, and painted surfaces, as well as vegetation. Product manufacturers' instructions should always be closely followed to avoid such inadvertent "collateral" damage.