Thursday, 24 March 2011 15:03

Metalworking

Rate this item
(1 Vote)

Metalworking involves casting, welding, brazing, forging, soldering, fabrication and surface treatment of metal. Metalworking is becoming even more common as artists in developing countries are also starting to use metal as a basic sculptural material. While many art foundries are commercially run, art foundries are also often part of college art programmes.

Hazards and Precautions

Casting and foundry

Artists either send work out to commercial foundries, or can cast metal in their own studios. The lost wax process is often used for casting small pieces. Common metals and alloys used are bronze, aluminium, brass, pewter, iron and stainless steel. Gold, silver and sometimes platinum are used for casting small pieces, particularly for jewellery.

The lost wax process involves several steps:

  1. making the positive form
  2. making the investment mould
  3. burning out of the wax
  4. melting the metal
  5. slagging
  6. pouring the molten metal into the mould
  7. removing the mould

 

The positive form can be made directly in wax; it can also be made in plaster or other materials, a negative mould made in rubber and then the final positive form cast in wax. Heating the wax can result in fire hazards and in decomposition of the wax from overheating.

The mould is commonly made by applying an investment containing the cristobalite form of silica, creating the risk of silicosis. A 50/50 mixture of plaster and 30-mesh sand is a safer substitute. Moulds can also be made using sand and oil, formaldehyde resins and other resins as binders. Many of these resins are toxic by skin contact and inhalation, requiring skin protection and ventilation.

The wax form is burnt out in a kiln. This requires local exhaust ventilation to remove the acrolein and other irritating wax decomposition products.

Melting the metal is usually done in a gas-fired crucible furnace. A canopy hood exhausted to the outside is needed to remove carbon monoxide and metal fumes, including zinc, copper, lead, aluminium and so on.

The crucible containing the molten metal is then removed from the furnace, the slag on the surface removed and the molten metal poured into the moulds (figure 1). For weights under 80 pounds of metal, manual lifting is normal; for greater weights, lifting equipment is needed. Ventilation is needed for the slagging and pouring operations to remove metal fumes. Resin sand moulds can also produce hazardous decomposition products from the heat. Face shields protecting against infrared radiation and heat, and personal protective clothing resistant to heat and molten metal splashes are essential. Cement floors must be protected against molten metal splashes by a layer of sand.

Figure 1. Pouring molten metal in art foundry.

ENT060F1

Ted Rickard

Breaking away the mould can result in exposure to silica. Local exhaust ventilation or respiratory protection is needed. A variation of the lost wax process called the foam vaporization process involves using polystyrene or polyurethane foam instead of wax, and vaporizing the foam during pouring of the molten metal. This can release hazardous decomposition products, including hydrogen cyanide from polyurethane foam. Artists often use scrap metal from a variety of sources. This practice can be dangerous due to possible presence of lead- and mercury-containing paints, and to the possible presence of metals like cadmium, chromium, nickel and so on in the metals.

Fabrication

Metal can be cut, drilled and filed using saws, drills, snips and metal files. The metal filings can irritate the skin and eyes. Electric tools can cause electric shock. Improper handling of these tools can result in accidents. Goggles are needed to protect the eyes from flying chips and filings. All electrical equipment should be properly grounded. All tools should be carefully handled and stored. Metal to be fabricated should be securely clamped to prevent accidents.

Forging

Cold forging utilizes hammers, mallets, anvils and similar tools to change the shape of metal. Hot forging involves additionally heating the metal. Forging can create great amounts of noise, which can cause hearing loss. Small metal splinters may damage the skin or eyes if precautions are not taken. Burns are also a hazard with hot forging. Precautions include good tools, eye protection, routine clean-up, proper work clothing, isolation of the forging area and wearing ear plugs or ear muffs.

Hot forging involves the burning of gas, coke or other fuels. A canopy hood for ventilation is needed to exhaust carbon monoxide and possible polycyclic aromatic hydrocarbon emissions, and to reduce heat build-up. Infrared goggles should be worn for protection against infrared radiation.

Surface treatment

Mechanical treatment (chasing, repousse) is done with hammers, engraving with sharp tools, etching with acids, photoetching with acids and photochemicals, electroplating (plating a metallic film onto another metal) and electroforming (plating a metallic film onto a non-metallic object) with acids and cyanide solutions and metal colouring with many chemicals.

Electroplating and electroforming often use cyanide salts, ingestion of which can be fatal. Accidental mixing of acids and the cyanide solution will produce hydrogen cyanide gas. This is hazardous through both skin absorption and inhalation—death can occur within minutes. Disposal and waste management of spent cyanide solutions is strictly regulated in many countries. Electroplating with cyanide solutions should be done in a commercial plant; otherwise use substitutes that do not contain cyanide salts or other cyanide-containing materials.

Acids are corrosive, and skin and eye protection is needed. Local exhaust ventilation with acid-resistant ductwork is recommended.

Anodizing metals such as titanium and tantalum involves oxidizing these at the anode of an electrolytic bath to colour them. Hydrofluoric acid can be used for precleaning. Avoid using hydrofluoric acid or use gloves, goggles and a protective apron.

Patinas used to colour metals can be applied cold or hot. Lead and arsenic compounds are very toxic in any form, and others can give off toxic gases when heated. Potassium ferricyanide solutions will give off hydrogen cyanide gas when heated, arsenic acid solutions give off arsine gas and sulphide solutions give off hydrogen sulphide gas. Very good ventilation is needed for metal colouring (figure 2). Arsenic compounds and heating of potassium ferrocyanide solutions should be avoided.

Figure 2. Applying a patina to metal with slot exhaust hood.

ENT060F2

Ken Jones

Finishing processes

Cleaning, grinding, filing, sandblasting and polishing are some final treatments for metal. Cleaning involves the use of acids (pickling). This involves the hazards of handling acids and of the gases produced during the pickling process (such as nitrogen dioxide from nitric acid). Grinding can result in the production of fine metal dusts (which can be inhaled) and heavy flying particles (which are eye hazards).

Sandblasting (abrasive blasting) is very hazardous, particularly with actual sand. Inhalation of fine silica dust from sandblasting can cause silicosis in a short time. Sand should be replaced with glass beads, aluminium oxide or silicon carbide. Foundry slags should be used only if chemical analysis shows no silica or dangerous metals such as arsenic or nickel. Good ventilation or respiratory protection is needed.

Polishing with abrasives such as rouge (iron oxide) or tripoli can be hazardous since rouge can be contaminated with large amounts of free silica, and tripoli contains silica. Good ventilation of the polishing wheel is needed.

Welding

Physical hazards in welding include the danger of fire, electric shock from arc-welding equipment, burns caused by molten metal sparks, and injuries caused by excessive exposure to infrared and ultraviolet radiation. Welding sparks can travel 40 feet.

Infrared radiation can cause burns and eye damage. Ultraviolet radiation can cause sunburn; repeated exposure may lead to skin cancer. Electric arc welders in particular are subject to pink eye (conjunctivitis), and some have cornea damage from UV exposure. Skin protection and welding goggles with UV- and IR-protective lenses are needed.

Oxyacetylene torches produce carbon monoxide, nitrogen oxides and unburned acetylene, which is a mild intoxicant. Commercial acetylene contains small amounts of other toxic gases and impurities.

Compressed gas cylinders can be both explosive and fire hazards. All cylinders, connections and hoses must be carefully maintained and inspected. All gas cylinders must be stored in a location which is dry, well ventilated and secure from unauthorized persons. Fuel cylinders must be stored separately from oxygen cylinders.

Arc welding produces enough energy to convert the air’s nitrogen and oxygen to nitrogen oxides and ozone, which are lung irritants. When arc welding is done within 20 feet of chlorinated degreasing solvents, phosgene gas can be produced by the UV radiation.

Metal fumes are generated by the vaporization of metals, metal alloys and the electrodes used in arc welding. Fluoride fluxes produce fluoride fumes.

Ventilation is needed for all welding processes. While dilution ventilation may be adequate for mild steel welding, local exhaust ventilation is necessary for most welding operations. Moveable flanged hoods, or lateral slot hoods should be used. Respiratory protection is needed if ventilation is not available.

Many metal dusts and fumes can cause skin irritation and sensitization. These include brass dust (copper, zinc, lead and tin), cadmium, nickel, titanium and chromium.

In addition, there are problems with welding materials that may be coated with various substances (e.g., lead or mercury paint).

 

Back

Read 6379 times Last modified on Tuesday, 06 September 2011 11:48
More in this category: « Photography New Technology in Art »

" DISCLAIMER: The ILO does not take responsibility for content presented on this web portal that is presented in any language other than English, which is the language used for the initial production and peer-review of original content. Certain statistics have not been updated since the production of the 4th edition of the Encyclopaedia (1998)."

Contents

Entertainment and the Arts References

American Academy of Orthopedic Surgeons. 1991. Protective equipment. In Athletic Training and Sports Medicine. Park Ridge, IL: APOS.

Arheim, DD. 1986. Dance Injuries: Their Prevention and Care. St. Louis, MO: CV Mosby Co.

Armstrong, RA, P Neill, and R Mossop. 1988. Asthma induced by ivory dust: A new occupational cause. Thorax 43(9):737-738.

Axelsson, A and F Lindgren. 1981. Hearing in classical musicians. Acta Oto-Larynogologica 92 Suppl. 377:3-74.

Babin, A 1996. Orchestra pit sound level measurements in Broadway shows. Presented at the 26th Annual Meeting of the American Public Health Association. New York, 20 November.

Baker, EL, WA Peterson, JL Holtz, C Coleman, and PJ Landrigan. 1979. Subacute cadmium intoxication in jewellery workers: an evaluation of diagnostic procedures. Arch Environ Health 34:173-177.

Balafrej, A, J Bellakhdar, M El Haitem, and H Khadri. 1984. Paralysis due to glue in young apprentice shoemakers in the medina of Fez. Rev Pediatrie 20(1):43-47.

Ballesteros, M, CMA Zuniga, and OA Cardenas. 1983. Lead concentrations in the blood of children from pottery-making families exposed to lead salts in a Mexican village. B Pan Am Health Organ 17(1):35-41.

Bastian, RW. 1993. Benign mucosal and saccular disorders; benign laryngeal tumors. In Otolaryngology-Head and Neck Surgery, edited by CW Cumming. St. Louis, MO: CV Mosby Co.

—. 1996. Vocal fold microsurgery in singers. Journal of Voice 10(4):389-404

Bastian, R, A Keidar, and K Verdolini-Marston. 1990. Simple vocal tasks for detecting vocal fold swelling. Journal of Voice 4(2):172-183.

Bowling, A. 1989. Injuries to dancers: Prevalence, treatment and perception of causes. British Medical Journal 6675:731-734.

Bruno, PJ, WN Scott, and G Huie. 1995. Basketball. In The Team Physicians’s Handbook, edited by MB Mellion, WM Walsh and GL Shelton. Philadelphia, PA: Mosby Yearbook.

Burr, GA, TJ Van Gilder, DB Trout, TG Wilcox, and R Friscoll. 1994. Health Hazard Evaluation Report: Actors’ Equity Association/The League of American Theaters and Producers, Inc. Doc. HETA 90-355-2449. Cincinnati, OH: US National Institute for Occupational Safety and Health.

Calabrese, LH, DT Kirkendal, and M Floyd. 1983. Menstrual abnormalities, nutritional patterns and body composition in female classical ballet dancers. Phys Sports Med 11:86-98.

Cardullo, AC, AM Ruszkowski, and VA DeLeo. 1989. Allergic contact dermatitis resulting from sensitivity to citrus peel, geriniol, and citral. J Am Acad Dermatol 21(2):395-397.

Carlson, T. 1989. Lights! Camera! Tragedy. TV Guide (26 August):8-11.

Chasin, M and JP Chong. 1992. A clinically efficient hearing protection program for musicians. Med Prob Perform Artists 7(2):40-43.

—. 1995. Four environmental techniques to reduce the effect of music exposure on hearing. Med Prob Perform Artists 10(2):66-69.

Chaterjee, M. 1990. Ready-made garment workers in Ahmedabad. B Occup Health Safety 19:2-5.

Clare, PR. 1990. Football. In The Team Physicians’s Handbook, edited by MB Mellion, WM Walsh, and GL Shelton. St. Louis, MO: CV Mosby Co.

Cornell, C. 1988. Potters, lead and health—Occupational safety in a Mexican village (meeting abstract). Abstr Pap Am Chem S 196:14.

Council on Scientific Affairs of the American Medical Association. 1983. Brain injury in boxing. JAMA 249:254-257.

Das, PK, KP Shukla, and FG Ory. 1992. An occupational health programme for adults and children in the carpet weaving industry, Mirzapur, India: A case study in the informal sector. Soc Sci Med 35(10):1293-1302.

Delacoste, F and P Alexander. 1987. Sex Work: Writings by Women in the Sex Industry. San Francisco, CA: Cleis Press.

Depue, RH and BT Kagey. 1985. A proportionate mortality study of the acting profession. Am J Ind Med 8:57-66.

Dominguez, R, JR DeJuanes Paardo, M Garcia Padros, and F Rodriguez Artalejo. 1987. Antitetanic vaccination in a high-risk population. Med Segur Trab 34:50-56.

Driscoll, RJ, WJ Mulligan, D Schultz, and A Candelaria. 1988. Malignant mesothelioma: a cluster in a Native American population. New Engl J Med 318:1437-1438.

Estébanez, P, K Fitch, and Nájera 1993. HIV and female sex workers. Bull WHO 71(3/4):397-412.

Evans, RW, RI Evans, S Carjaval, and S Perry. 1996. A survey of injuries among Broadway performers. Am J Public Health 86:77-80.

Feder, RJ. 1984. The professional voice and airline flight. Otolaryngology-Head and Neck Surgery, 92(3):251-254.

Feldman, R and T Sedman. 1975. Hobbyists working with lead. New Engl J Med 292:929.

Fishbein, M. 1988. Medical problems among ICSOM musicians. Med Prob Perform Artists 3:1-14.

Fisher, AA. 1976. “Blackjack disease” and other chromate puzzles. Cutis 18(1):21-22.

Frye, HJH. 1986. Incidence of overuse syndrome in the symphony orchestra. Med Prob Perform Artists 1:51-55.

Garrick, JM. 1977. The frequency of injury, mechanism of injury and epidemiology of ankle sprains. Am J Sports Med 5:241-242.

Griffin, R, KD Peterson, J Halseth, and B Reynolds. 1989. Radiographic study of elbow injuries in professional rodeo cowboys. Phys Sports Med 17:85-96.

Hamilton, LH and WG Hamilton. 1991. Classical ballet: Balancing the costs of artistry and athleticism. Med Prob Perform Artists 6:39-44.

Hamilton, WG. 1988. Foot and ankle injuries in dancers. In Sports Clinics of North America, edited by L Yokum. Philadelphia, PA: Williams and Wilkins.

Hardaker, WTJ. 1987. Medical considerations in dance training for children. Am Fam Phys 35(5):93-99.

Henao, S. 1994. Health Conditions of Latin American Workers. Washington, DC: American Public Health Association.

Huie, G and EB Hershman. 1994. The team clinician’s bag. Am Acad Phys Asst 7:403-405.

Huie, G and WN Scott. 1995. Assessment of ankle sprains in athletes. Phys Assist J 19(10):23-24.

Kipen, HM and Y Lerman. 1986. Respiratory abnormalities among photographic developers: A report of 3 cases. Am J Ind Med 9:341-347.

Knishkowy, B and EL Baker. 1986. Transmission of occupational disease to family contacts. Am J Ind Med 9:543-550.

Koplan, JP, AV Wells, HJP Diggory, EL Baker, and J Liddle. 1977. Lead absorption in a community of potters in Barbados. Int J Epidemiol 6:225-229.

Malhotra, HL. 1984. Fire safety in assembly buildings. Fire Safety J 7(3):285-291.

Maloy, E. 1978. Projection booth safety: New findings and new dangers. Int Assoc Electr Inspect News 50(4):20-21.

McCann, M. 1989. 5 dead in movie heliocopter crash. Art Hazards News 12:1.

—. 1991. Lights! Camera! Safety! A Health and Safety Manual for Motion Picture and Television Production. New York: Center for Safety in the Arts.

—. 1992a. Artist Beware. New York: Lyons and Burford.

—. 1992b. Art Safety Procedures: A Health and Safety Manual for Art Schools and Art Departments. New York: Center for Safety in the Arts.

—. 1996. Hazards in cottage industries in developing countries. Am J Ind Med 30:125-129.

McCann, M, N Hall, R Klarnet, and PA Peltz. 1986. Reproductive hazards in the arts and crafts. Presented at the Annual Conference of the Society for Occupational and Environmental Health Conference on Reproductive Hazards in the Environment and Workplace, Bethesda, MD, 26 April.

Miller, AB, DT Silverman, and A Blair. 1986. Cancer risk among artistic painters. Am J Ind Med 9:281-287.

MMWR. 1982. Chromium sensitization in an artist’s workshop. Morb Mort Weekly Rep 31:111.

—. 1996. Bull riding-related brain and spinal cord injuries—Louisiana, 1994-1995. Morb and Mort Weekly Rep 45:3-5.

Monk, TH. 1994. Circadian rhythms in subjective activation, mood, and performance efficiency. In Principles and Practice of Sleep Medicine, 2nd edition, edited by M. Kryger and WC. Roth. Philadelphia, PA: WB Saunders.

National Institute for Occupational Safety and Health (NIOSH). 1991. Environmental Tobacco Smoke in the Workplace: NIOSH Current Intelligence Bulletin 54. Cincinnati, OH: NIOSH.

Norris, RN. 1990. Physical disorders of visual artists. Art Hazards News 13(2):1.

Nubé, J. 1995. Beta Blockers and Performing Musicians. Doctoral thesis. Amsterdam: University of Amsterdam.

O’Donoghue, DH. 1950. Surgical treatment of fresh injuries to major ligaments of the knee. J Bone Joint Surg 32:721-738.

Olkinuora, M. 1984. Alcoholism and occupation. Scand J Work Environ Health 10(6):511-515.

—. 1976. Injuries to the knee. In Treatment of Injuries to Athletes, edited by DH O’Donoghue. Philadelphia, PA: WB Saunders.

Pan American Health Organization, (PAHO). 1994. Health Conditions in the Americas. Vol. 1. Washington, DC: PAHO.

Pheterson, G. 1989. The Vindication of the Rights of Whores. Seattle, WA: Seal Press.

Prockup, L. 1978. Neuropathy in an artist. Hosp Pract (November):89.

Qualley, CA. 1986. Safety in the Artroom. Worcester, MA: Davis Publications.

Ramakrishna, RS, P Muthuthamby, RR Brooks, and DE Ryan. 1982. Blood lead levels in Sri Lankan families recovering gold and silver from jewellers’ waste. Arch Environ Health 37(2):118-120.

Ramazzini, B. 1713. De morbis artificum (Diseases of Workers). Chicago, IL: University of Chicago Press.

Rastogi, SK, BN Gupta, H Chandra, N Mathur, PN Mahendra, and T Husain. 1991. A study of the prevalence of respiratory morbidity among agate workers. Int Arch Occup Environ Health 63(1):21-26.

Rossol, M. 1994. The Artist’s Complete Health and Safety Guide. New York: Allworth Press.

Sachare, A.(ed.). 1994a. Rule #2. Section IIC. In The Official NBA Basketball Encyclopedia. New York: Villard Books.

—. 1994b. Basic Principle P: Guidelines for infection control. In The Official NBA Basketball Encyclopedia. New York: Villard Books.

Sammarco, GJ. 1982. The foot and ankle in classical ballet and modern dance. In Disorders of the Foot, edited by MH Jahss. Philadelphia, PA: WB Saunders.

Sataloff, RT. 1991. Professional Voice: The Science and Art of Clinical Care. New York: Raven Press.

—. 1995. Medications and their effect on the voice. Journal of Singing 52(1):47-52.

—. 1996. Pollution: Consequences for singers. Journal of Singing 52(3):59-64.

Schall, EL, CH Powell, GA Gellin, and MM Key. 1969. Hazards to go-go dancers to exposures to “black” light from fluorescent bulbs. Am Ind Hyg Assoc J 30:413-416.

Schnitt, JM and D Schnitt. 1987. Psychological aspects of dance. In The Science of Dance Training, edited by P Clarkson and M Skrinar. Champaign, IL: Human Kinetics Press.

Seals, J. 1987. Dance surfaces. In Dance Medicine: A Comprehensive Guide, edited by A Ryan and RE Stephens. Chicago, IL: Pluribus Press.

Sofue, I, Y Yamamura, K Ando, M Iida, and T Takayanagi. 1968. N-hexane polyneuropathy. Clin Neurol 8:393-403.

Stewart, R and C Hake. 1976. Paint remover hazard. JAMA 235:398.

Tan, TC, HC Tsang, and LL Wong. 1990. Noise surveys in discotheques in Hong Kong. Ind Health 28(1):37-40.

Teitz, C, RM Harrington, and H Wiley. 1985. Pressure on the foot in point shoes. Foot Ankle 5:216-221.

VanderGriend, RA, FH Savoie, and JL Hughes. 1991. Fracture of the ankle. In Rockwood and Green’s Fractures in Adults, edited by CA Rockwood, DP Green, and RW Bucholz. Philadelphia, PA: JB Lippincott Co.

Warren, M, J Brooks-Gunn, and L Hamilton. 1986. Scoliosis and fracture in young ballet dancers: Relationship to delayed menarcheal age and amenorrhea. New Engl J Med 314:1338-1353.

World Health Organization (WHO). 1976. Meeting on Organization of Health Care in Small Industries. Geneva: WHO.

Zeitels, S. 1995. Premalignant epithelium and microinvasive cancer of the vocal fold: the evolution of phonomicrosurgical management. Laryngoscope 105(3):1-51.