ART SAFETY PROCEDURES FOR ART SCHOOLS AND ART DEPARTMENTS CHAPTER 6. GENERAL PRECAUTIONS This chapter discusses general precautions that should be taken when using art materials and processes. Personal protective equipment is discussed in Chapter 7, fire safety in Chapter 8, waste management and disposal in Chapter 9, and safety in Chapter 10. KNOW YOUR MATERIALS Knowing the contents of art materials and their hazards is essential to having a safe studio program. Labels and Materials Safety Data Sheets (MSDSs) are keys to finding this information. As discussed in Chapter 3, OSHA, as part of its Hazard Communication Standard, requires that employers have proper labeling on containers and have MSDSs for all hazardous products. Keeping an up-to-date inventory of all products, including names, amounts, date purchased, and special hazards, is also recommended. SUBSTITUTION One of the most basic rules of chemical safety is to use the safest materials and processes possible. Examples include: * Use the least toxic solvents possible (e.g. denatured alcohol, isopropyl alcohol, acetone, odorless mineral spirits). * Eliminate toxic metals such as lead and cadmium (e.g. using cadmium-free silver solders and lead-free glazes and enamels. * Use water-based materials instead of solvent-based ones (e.g. water-based silk screen inks and water-based paints). * Use liquid materials to replace powders (e.g. wet clay or water-based dyes instead of dry clay or powdered dyes). * Use wet techniques instead of dry techniques (e.g. wet sanding, wet grinding). * Apply coatings by brushing or dipping instead of spraying. * Eliminate cancer-causing chemicals (e.g. asbestos, cadmium fumes, lead and zinc chromate, benzene, and chromated copper arsenate). It is important when substituting one material for another to allow sufficient time to learn how to use the substitute properly. For example, it can take a semester to properly switch from solvent-based to water-based screen printing inks. VENTILATION There are three reasons for ventilation: 1) for toxic airborne chemicals, 2) to prevent a build-up of flammable gases or vapors, and 3) for comfort of the inhabitants of the area. Since health effects of chemicals occur at air concentrations well below the lower explosive limits of solvents and gases, then if you ventilate to prevent health effects, you are also preventing a buildup of vapors which could catch fire or explode. There are two types of ventilation for toxic substances: dilution ventilation, and local exhaust ventilation. Dilution ventilation involves bringing in clean air to dilute the contaminated air, and then exhausting the diluted air to the outside via exhaust fans. An open door or window, or recirculating air-conditioning system is not adequate dilution ventilation for toxic gases and vapors. Local exhaust ventilation involves trapping airborne contaminants at their source before they contaminate the air which is breathed. Examples include spray booths and dust-collecting hoods. (For further information on ventilation for toxic substances, see the CSA book Ventilation.) Ventilation for comfort is usually done through heating, ventilating and air-conditioning systems. Dilution Ventilation Dilution ventilation should not be used to exhaust large amounts of toxic solvent vapors, or for highly toxic solvent vapors, because of the requirement for large amounts of makeup or replacement air to replace the air being exhausted. This makeup air has to be heated or cooled to a comfortable temperature. Dilution ventilation should also not be used for dusts or fumes because of the difficulty of calculating the amount of dilution air required. The exhausted air should be completely exhausted to the outside and not recirculated. For solvents, the amount of exhaust ventilation required can be calculated by the procedure on pages 26-28 of Ventilation. For example, if 1 pint of mineral spirits is used in cleaning intaglio inking slabs and presses over a 3-hour class period, then the amount of dilution ventilation required would be: total amt evaporated x dilution volume/pint x K /# minutes = 1 pt x 35,000 cu. ft/pint x 10 / 180 minutes = 1950 cubic feet/minute (cfm). where the dilution volume for mineral spirits is 35,000 cu. ft/pt and safety factor K = 10. The dilution volume is the volume of air required to dilute one pint of evaporated solvent to the Threshold Limit Value for that solvent. (See Table 6-1 for the dilution volumes of common solvents used in art.) Table 6-1. Dilution Volumes for Common Solvents Solvent Dilution volume (cu. ft./pint) Acetone 7,300 Ethyl alcohol 6,900 n-Hexane 61,700 n-Heptane 6,900 1,1,1-Trichloroethane 11,400 Methyl ethyl ketone 22,500 Methylene chloride 126,800 Mineral spirits 30,000-35,000 Toluene 76,000 Turpentine 25,500 Xylene 33,000 Local Exhaust Ventilation A local exhaust ventilation system consists of a hood to capture the contaminants, ducts to transport them to the outside, an exhaust fan to move the air, and sometimes air cleaners to remove particulates from the air. The only air cleaners I would recommend are filters in spray booths and dust collectors for woodworking and other dust-producing machines. Charcoal filters are not recommended because of large amounts of charcoal required and the difficulty of telling when the charcoal is saturated. Particular types of hoods are used for particular operations. OSHA requires local exhaust ventilation for abrasive blasting, grinding, polishing and buffing, spray finishing, and open surface tanks (23 CFR 1910.94). Examples of typical local exhaust systems for art operations include canopy hoods over electric kilns, slot exhaust hoods for cleaning etching plates, enclosed hoods for acid etching, spray booths for spray painting and spray glazes, movable exhaust hoods for welding, and dust-collecting hoods for woodshops. In many instances, either a slot exhaust hood or enclosed hood can provide adequate local exhaust ventilation. If practical, an enclosed hood requires a lower exhaust rate and therefore less makeup air. For example, a 3-foot slot exhaust hood would require an exhaust rate of 1050 cfm. By comparison, an enclosed hood with a 3-foot by 18-inch (1.5 ft) opening would require only 360 cfm. Thus an enclosed hood, if practical for the type or work being done, can result in lowered energy costs for makeup air. Some rules for operation of local exhaust systems are: * Provide adequate makeup air. Ensure that the air intakes are not located near truck loading platforms, exhaust air outlets, furnace chimneys, etc. This makeup air should not enter the room close enough to the exhaust hood to create turbulence and affect the hood's capturing contaminants. * Direct the flow of air so that clean air passes your face before becoming contaminated and being exhausted. * Enclose the process as much as possible. * Place the hood as close to the operation as possible. * Fans should be located outside so all ducts are under negative pressure, and to decrease noise levels. * Do not recirculate any of the exhausted air. * Make sure exhausted air cannot reenter the area (or other areas). * Always test the exhaust systems when it is installed. This should include smoke tube observations at hood openings to ensure adequate capture of contaminants. A child's soap bubble kit will also work. The engineer designing the ventilation system should instruct maintenance and other individuals responsible for the system in the complete operation and maintenance of the system before signing off on the project. * Ducting should be round not rectangular, and have as few elbows as possible to reduce friction. These bends should be gradual not sharp. If needed, ducting should be corrosion-resistant. * Spark-proof construction of exhaust systems and placing fan motors outside the airstream is important for all local exhaust ductwork systems exhausting flammable gases and vapors. * Provide regular maintenance. If the college does not have personnel with industrial ventilation experience, then hiring an outside firm for maintenance is recommended. In selecting an engineer to design a ventilation system for toxic substances, it is important to choose someone experienced in industrial ventilation. Most heating, ventilating and air-conditioning engineers do not have this experience. Comfort Ventilation If a studio or office does not use toxic chemicals that can become airborne, then the only ventilation needed is for the comfort of the inhabitants of the area. The American Society of Heating, Refrigerating and Air-Conditioning Engineers is the traditional source of information on comfort ventilation through its standard ASHRAE 62-1989 Ventilation for Acceptable Indoor Air Quality. ASHRAE 62-1989 is based on the concept of specifying minimum and recommended outdoor air flow rates to obtain acceptable indoor air quality for a variety of indoor air spaces. This standard is referenced in many building codes. This standard does not provide acceptable air quality for everyone. An appendix to the standard says that "The air can be considered acceptably free of annoying contaminants if 80% of a panel of at least 20 untrained observers deems the air to be not objectionable under representative conditions of use and occupancy." Table 6-2 contains selected minimum outdoor air quality requirements taken from Table 2 of ASHRAE 62-1989. Table 6-2. Minimum Outdoor Air Requirements (ASHRAE 62-1989) Estimated maximum Outdoor air occupancy requirements (people/1000 sq ft) (cfm/person) office space 7 20 classrooms 50 15 laboratories 30 20 training shops 30 20 libraries 20 15 corridors 0.1 cfm/sq. ft. auditoriums 150 15 smoking lounges 70 60 Obviously, these minimum outdoor air requirements do not apply if toxic chemicals are being emitted into the air. STORAGE AND HANDLING OF TOXIC CHEMICALS Storage * Keep the minimum amount of materials on hand and purchase in smallest practical container size in order to reduce risk in case of spills or fire, and to minimize waste disposal costs. See also the section in Chapter 8 on flammable and combustible liquids. * Choose appropriate containers. Avoid breakable glass containers whenever possible. * Dyes and other powdered materials that come in small paper bags should be transferred to solid containers or sealed plastic bags to avoid tears in bags releasing dust into the air. * All containers should be labeled with contents and hazards. * Store art materials safely so they will not fall. Hazardous chemicals should not be stored above eye level. * Do not store chemicals that can react with each other in close proximity. The reactivity section of Material Safety Data Sheets describe the chemical incompatibilities of their products. Table 6-3 lists the incompatibility of common chemicals found in art materials. * Do not store chemicals in food refrigerators or in food containers. Use separate refrigerators, which should be explosion-proof if flammable chemicals are stored there. Handling * Cover containers to prevent liquids from evaporating and powders from spilling. * Use a glove box to mix small amounts of powders. This can be made out of cardboard. Take a cardboard box, put two holes in the sides for gloved hands, place container of liquid and powder inside box and cover with glass or plexiglass top. The inside of the box can be shellaced for easy cleaning. * Transfer powders carefully to avoid getting large amounts of dust in the air. * Pour liquids carefully to avoid splashing, using a funnel where possible. * Wear appropriate personal protective equipment. See Chapter 7 for more information. ------------------------------------------------------------------------ Table 6-3. Incompatibilities of Common Art Materials Chemical Incompatibilities Acetic acid chromates, dichromates, chlorates, nitric acid, hydrogen peroxide, and other oxidizers Acids, inorganic alkalis, hypochlorite bleach, sulfides, metals Alkalis acids, aluminum Ammonium hydroxide silver, chlorine, bromine, mercury, acids Chlorinated ultraviolet radiation, hydrocarbons aluminum Chromates and glacial acetic acid, camphor, dichromates glycerin, naphthalene, turpentine, and many other flammable liquids Copper hydrogen peroxide, many acids, acetylene Cyanides, inorganic acids, alkalis Flammable liquids chromates, dichromates, chlorates, nitric acid, hydrogen peroxide, and other oxidizers Hydrofluoric acid ammonium hydroxide, glass, Hydrogen peroxide most metals and their salts, (concentrated) organic substances, many flammable liquids Mercury nitric acid, ammonia Nitrates, inorganic acids, metals, nitrites, sulfur Nitric acid metals, sulfuric acid, sulfides, nitrites, solvents, combustible materials, chromates, dichromates Peroxides, organic acetone, heat Potassium chlorate ammonium salts, acids, metal powders, finely divided organic or combustible substances Silver acetylene, ammonia compounds, oxalic acid, tartaric acid Sulfides, inorganic acids Sulfites, bisulfites acids, Sulfuric acid nitric acid, metals, chlorates, permanganates ----------------------------------------------------------------------- WORK PRACTICES AND HYGIENE * Do not eat, drink, smoke, apply makeup or chew gum in the work area. * Wash hands after work. Never use turpentine or other solvents to clean hands; instead use soap and water or a safe waterless hand cleanser (obtained from a safety supply house). Baby oil will remove paint from hands. * Wear separate clothes in the studio and wash separately from other clothes. Housekeeping * Dusts should always be wet mopped or vacuumed, never swept. Sweeping just stirs up the dust. * Highly toxic dusts like clay dust, asbestos, and lead dusts require a special high efficiency (HEPA) vacuum cleaner because very fine dusts go right through normal industrial vacuum cleaners. * Cement floors should be sealed with commercial cement sealers or even paint to make cleanup easier. * Dusty work surfaces should be wet mopped daily. REFERENCES 1. Clark, N., Cutter, T., and McGrane, J. (1984). Ventilation. Lyons and Burford, Publishers, New York, NY. * 2. Committee on Industrial Ventilation. (1988). Industrial Ventilation: A Manual of Practice. 20th ed., American Conference of Governmental Industrial Hygienists, East Lansing, MI. Updated regularly. 3. Council of State Science Supervisors. (1984) School Science Laboratories: A Guide to Some Hazardous Substances, U.S. Consumer Product Safety Commission, Washington, DC. 4. McCann, M. (1992). Artist Beware. 2nd ed., Lyons and Burford Publishers, New York, NY. * 5. McCann, M. (1985). Health Hazards Manual for Artists, 3rd ed, Lyons and Burford Publishers, New York, NY.* 6. National Research Council Committee on Hazardous Substances in the Laboratory. (1981). Prudent Practices for Handling Hazardous Chemicals in Laboratories. National Academy Press, Washington, DC.