Metal Working

ID Metal-working Tech Ingestion Haz Inhalation
Skin Contact Hazard Other







Oxyacetylene Welding Fire Hazards




Fire and explosion hazards

Welding surface should be fireproof, made of steel or firebrick; don't use asbestos sheeting; wooden floors & walls should be covered with fireproof materials; remove combustibles/ flammables; don't weld on containers that have held combustibles/ flammables


Oxyacetylene Welding Cylinder Precautions





Don't move cylinders w/out valve protection cap;make sure hoses can't be tripped over/don't contact grease;make sure connections are gas tight;use proper tools to open valves away from self;purge lines to remove mixed gases;close valves before relighting


Oxyacetylene Welding Safety Hazards



Thermal burns

Hot metal, flying sparks, infrared radiation can cause severe thermal burns on exposed skin

Wear leather gloves, long-sleeve 100% wool or flame-retardant cotton shirts, pants, leather apron to protect from burns; don't wear flammable clothing w/cuffs, pockets; wear hightop leather boots w/out rubber/crepe soles & do have safety toes


Oxyacetylene Welding Health Hazards


Phosgene extremely toxic; carbon dioxide, acetylene cut off oxygen to lungs; carbon monoxide & fluoride flux fumes highly toxic; metal fume fever; metal dusts irritating; metal fumes highly toxic

UV can cause skin cancer, eye damage, sunburn; can react w/ chlorinated hydrocarbons to form phosgene

Visible light can cause eye strain/headaches; infrared radiation can cause skin burns/ chronic eye inflammation/ heat cataracts; copper/ zinc/ iron/ nickel/ magnesium can cause metal fume fever; lead/cadmium/ manganese/ chromium/ beryllium/ nickel highly toxic

Wear welding goggles w/shade #4-8; don't store chlorinated hydrocarbons where uv light can reach; know composition of metals/rods; use dilution ventilation of at least 2,000 cubic feet/minute/welder; use local exhaust system, NIOSH-approved respirator


Arc Welding Safety Hazards




Increased risk of fire, thermal burns from sparks, heat stress; high risk of electric shock due to large electric currents used

Wear protective clothing/leather leggings/sleeves; prevent fire; install & ground electric arc welders according to manufacturer; cables/connectors should be of proper size, regularly inspected, & properly secured; inspect electrode holders, cables


Arc Welding Health Hazards


Ozone highly toxic/causes lung irritation/congestion/ chemical pneumonia/ chronic bronchitis, can be fatal; nitrogen dioxide highly toxic/causes chemical pneumonia, emphysema; metal fumes/ manganese/ fluoride fumes highly toxic

Eye damage from uv light

Chromates may cause lung irritation, allergies, nasal septum ulceration, lung cancer; plasma arc welders produce much higher concentrations of ozone, nitrogen dioxide, metal fumes & produce high noise levels

Use fireproof uv radiation screens around welding units; coat walls w/zinc oxide to reduce reflection; leave 20 inches at bottom of screen for ventilation; wear welding helmet over impact-resistant flash goggles (#10-14); use local exhaust ventilation








Mold Making


High-silica sands, silica flour, investment plasters highly toxic (can cause silicosis); formaldehyde extremely toxic; isocyanates highly toxic; asbestos extremely toxic; ethyl silicate highly toxic

Formaldehyde moderately toxic; hexamethylene-tetramine causes skin irritation by decomposing to formaldehyde

Formaldehyde known carcinogen; asbestos can cause lung cancer, mesothelioma, stomach/intestinal cancer; french chalk can contain high amts.of free silica

Use foundry sand for molds,not high-silica sands; use local exhaust ventilation when mixing silica, or use NIOSH-approved respirator; avoid formaldehyde/polyurethane resins; wear gloves, goggles; DO NOT use asbestos/silica flour/French chalk; use graphite


Burnout of the Pattern


Carbon monoxide highly toxic; wax decomposition fumes highly irritating; styrene, hydrogen cyanide gases highly toxic

Ventilate with local exhaust system (canopy hood over burnout furnace)


Melting the Metal


Carbon dioxide & carbon monoxide (highly toxic) from furnace; lead fumes from lead metal & bronze highly toxic; zinc fumes from bronze & brass moderately toxic; nickel fumes may be extremely toxic (nickel carbonyl can be in it)

Natural gas/propane gas cause fire/explosion hazards; nickel fumes/dusts can cause lung/nasal cancer; using alloys of unknown composition can result in exposure to other toxic metals;furnace can cause heat stress; infrared radiation causes skin burns

Gas furnaces should be connected by gas company; use alloys of known composition only; avoid nickel/lead; use local exhaust ventilation;wear infrared goggles,face shield,long-sleeve wool shirt, insulated leggings, jacket, apron, gloves


Pouring the Metal


Hazardous metal fumes released during pouring; thermal decomposition of organic materials release formaldehyde, carbon monoxide, acrolein, cancer-causing substances; polyurethane foam can release hydrogen cyanide gas (extremely toxic)

Molten metal splashes can cause severe thermal burns

Manual pours limited by weight of crucible & person's strength; molten metal splashes on cement result in heat vaporizing water in cement, causing it to violently break apart in steam explosion

Make sure you can lift crucible; don't pour by yourself; use two-person shank and ring/mechanical lifting equipment; embed molds in damp sand 18 inches deep, enclosed in metal; foundry floor should have raised metal grate/covered w/sand; use canopy hood


Removing the Mold


Intense temperatures convert normal quartz sand to highly haz. silica; sandblasting can cause silicosis in a few years exposure


Abrasive blasting creates loud amounts of noise, which can cause hearing loss

Wear NIOSH-approved toxic dust respirator;vacuum/met mop;don't use sand for abrasive blasting;use alumina/silicon carbide/walnut shells;avoid foundry slags w/arsenic;inspect blasting machine often;wear hearing protection, protective clothing,blasting hood








Cutting, Piercing, & Filing Metals



Small metal filings can damage skin, eyes; saws, drills, metal snips can cause cuts

Electric drills can cause electric shocks if they're not properly grounded

Wear ANSI-approved goggles to protect eyes against flying metal pieces/filings; make sure electrical equipment properly grounded & wiring is in good condition; handle tools w/sharp edges carefully; fasten metal piece in vise; put tools away after use




Furnaces for hot forging give off large amounts of carbon monoxide and other highly toxic fumes & gases

Careless handling of hot objects can cause thermal burns; furnaces produce infrared radiation, which is an eye & skin hazard

Noise is a hearing hazard in both hot/cold forging; large amounts of heat from furnaces can cause heat stress

Do forging in separate room; wear ear plugs/ear muffs; equip all furnaces w/chimneys/canopy hoods; use exhaust fan; wear protective goggles (shade # 1.7-3.0); wear long-sleeve, cotton shirt, leather gloves, safety shoes, face shield; keep room cool





Sulfuric acid/other acids & Sparex highly corrosive to skin, eyes; diluted acid less haz., but can cause burns

Use of torches involves flammable gases, such as propane & acetylene, and oxygen/compressed air (fire & explosion hazards); furnaces can cause heat stress

Use precautions w/gas torches, fuel-fired furnaces; wear protective goggles, gloves, apron; add acid to water; use Sparex; avoid acids; if acid splashes on skin, rinse w/water, if in eyes, rinse for 15-20 minutes; neutralize acid w/sodium bicarbonate








Mechanical Treatment


Benzine (VM&P naphtha) moderately toxic

Benzine moderately toxic; hot pitch is skin irritant & frequent, prolonged contact can cause skin cancer

Heating pitch & use of benzine to remove pitch from the metal creates fire hazards; engraving tools can cause cuts if used improperly

Don't smoke/have open flames; store solvents in safety cans, store rags in disposal cans & remove each day; use adequate exhaust system; use gloves when handling hot pitch or benzine; handle engraving tools carefully; cut away from yourself


Etching & Photoetching


Nitrogen dioxide gas highly toxic, causing pulmonary edema, pneumonia, emphysema; methyl cellosolve acetate highly toxic; xylene highly toxic; carbon arcs give off nitrogen oxides, ozone, metal fumes (highly toxic)

Nitric acid/other acids highly corrosive to eyes,skin; methyl cellosolve acetate highly toxic; xylene moderately toxic; hot pitch can cause burns

Methyl cellosolve acetate can cause adverse reproductive effects, kidney damage, anemia; methyl cellosolve acetate & xylene flammable; carbon arcs emit ultraviolet radiation, which cause sunburn, eye damage; hot pitch is fire haz.

Wear gloves, goggles, protective apron, NIOSH-approved organic vapor respirator; add acid to water; if acid splashes on skin, rinse w/water, if in eyes, rinse for 15-20 minutes; use local exhaust system; use commercial resists; don't use carbon arcs


Electroplating & Electroforming


Sulfuric acid is respiratory irritant; lacquer vapors & mists highly toxic

Risk of electrical shock; caustic soda, sulfuric acid highly corrosive; sulfuric acid skin & eye irritant; lacquer vapors moderately irritating


Send pieces to commercial electroplater; wear rubber gloves, goggles, protective apron, NIOSH-approved respirator, rubber-soled shoes; add acid to water; if acid splashes on skin, rinse w/water, if in eyes, rinse 15-20 min.; use local exhaust system


Electroplating & Electroforming (continued)





Install ground fault circuit interrupter; install electroplating unit on wooden/nonconducting surface, not on metal; don't use metal chair; don't touch bath, wires, electrodes w/bare hands; unplug power before adjusting bath; use special rectifiers/tape



Hydrofluoric acid can be fatal

Trisodium phosphate alkaline & can cause respiratory irritation; hydrofluoric acid highly corrosive to lungs

Trisodium phosphate alkaline & can cause skin, eye irritation; hydrofluoric acid highly corrosive

Titanium & tantalum are combustible; their filings & dust will burn; burns can occur without pain hours after exposure to hydrofluoric acid; hydrofluoric acid can cause chemical pneumonia, chronic bone/teeth or kidney damage; risk of electrical shock

Wear insulating rubber gloves, goggles, protective apron, face shield; AVOID hydrofluoric acid, use wet sand & emery paper; only use hydrofluoric acid in lab hood or w/acid gas respirator; if contact w/skin/eyes, flush for 15 min. & call doctor right away



Patinas highly poisonous; concentrated acids highly corrosive; benzine moderately toxic

Chlorinated solvents highly toxic; patinas highly poisonous; spray mists haz.; concentrated acids highly corrosive; potassium cyanide forms poisonous hydrogen cyanide gas; benzine moderately toxic, lacquers highly toxic

Chlorinated solvents can be absorbed through skin; patinas corrosive; concentrated acids highly corrosive; benzine, lacquers moderately toxic

Chlorinated solvents probable carcinogens; if heated w/torch, decompose to poisonous phosgene gas; diluted acids cause skin, eye irritation; oxidizing agents can cause fires/explosions; benzine, lacquer solutions flammable

Use mineral spirits/detergent solutions to clean/degrease metals; don't use antimony/ arsenic/ cyanide/ mercury; wear goggles, gloves, protective apron; don't add acids to sulfides when coloring; store oxidizing agents away from solvents


Patinas (continued)





Use glove box, local exhaust ventilation, NIOSH-approved toxic dust respirator; don't eat, drink, smoke in studio; dip/brush patinas instead of spraying; don't have smoke/open flames in working area; dispose of waste solvents & rags daily



Lead sulfide dust from grinding highly toxic

Lead fumes emitted from melting of lead highly toxic; lead sulfide dust from grinding highly toxic


Do all melting & heating in local exhaust system; wear NIOSH-approved respirator; don't eat, drink, smoke in studio; wash hands carefully after work; wet mop surfaces; heat ammonium chloride paste inside a hood



Mercury metal poorly absorbed


Mercury metal highly toxic


Mercury metal highly toxic


Acute mercury poisoning is accompanied by metallic taste, excessive salivation, swelling of gums/mouth, vomiting, bloody diarrhea, kidney failure, bronchitis, pneumonia; chronic mercury poisoning affects central nervous system

DO NOT USE mercury amalgams; store mercury under water in closed containers; if mercury used, make amalgam on tray to contain spills; use local exhaust ventilation; clean up spills w/mercury spill kit; wash contaminated surfaces w/ferric chloride









Ammonium bifluoride highly toxic

Nitric & sulfuric acids highly toxic; hydrofluoric acid highly corrosive; potassium dichromate highly toxic

Nitric & sulfuric acid, ammonium bifluoride highly toxic; hydrofluoric acid highly corrosive; sodium bisulfate moderately corrosive; potassium dichromate moderately toxic

Boiling acid solutions can be very hazardous due to danger of splashing; dichromates are probable carcinogens; hydrofluoric acid can cause lung irritation, chemical pneumonia, chronic bone/teeth/kidney damage; may be fatal

Wear gloves, goggles, protective apron, respirator, face shield; if acid splashes on skin, rinse w/water; if in eyes, rinse for 15-20 min.; cover acid baths; use local exhaust ventilation; use bifluoride pastes; neutralize acid w/sodium bicarbonate


Grinding, Polishing, & Other Mechanical Techniques

Lead-containing dusts highly toxic

Lead-containing dusts highly toxic; free silica highly toxic, causing silicosis; formaldehyde highly irritating; silica-containing abrasives may cause silicosis from chronic inhalation

Cutting fluids may cause dermatitis

Flying metal particles can cause eye damage; synthetic, semisynthetic, soluble cutting oils contain nitrosamines, which cause cancer in animals

Wear goggles, face shield, respirator; grinding wheels should have eye shields; don't wear loose clothing; don't use sandstone wheels; use silicon carbide/alumina; use wet techniques; use local exhaust ventilation; use cutting oils w/out amines/nitrites