One of the best ways to decrease or eliminate a health hazard is to find a less toxic substitute. Some substances like asbestos, in particular, are so highly toxic that it is extremely difficult to work with it safely. This role is true, in general, of all substances that can cause cancer since most cur rent evidence indicates that there is no safe level of exposure to a carcinogen. It would be wise to follow this rule for all harmful substances.
Hygiene: In the Workshop and Personal Hygiene
When considering the layout for your shop, try to isolate the location for processes that Produce or involve health hazards to one section (room) of the studio, and give this area special attention such as lighting, ventilation, sinks for quick clean-ups, etc.
Good “housekeeping” and personal cleanliness are necessary to control and prevent health hazards in the workshop. Spills should be cleaned up immediately. It the area or substance to be cleaned contains potential health hazards, one should wear gloves and a respirator. When cleaning up it is preferable to vacuum with an industrial-type vacuum, or wet mop, instead of sweeping.
You should not eat or smoke in the studio. Before eating or smoking it is advisable to remove work gloves, bandanas, aprons, smocks, etc. Hands should be washed after using toxic substances. (Gentle hand soap is adequate. Harsh detergents can aggravate or cause dermatitis.)
If you live and work in the same place, a separate area should be set aside for your studio. One should be careful not to carry contaminants out of the studio into the living environment and into contact with other members of Your household. Children, especially, are much mom susceptible to harm caused by toxic substances. Work clothes should be left in the studio, washed frequently and separately from non-work clothes.
It is also important to store all potentially hazardous substances in their original container according to the manufacturer’s instructions.
Safety with Equipment Machinery
Welding, Soldering and Brazing: Fuel cylinders should be kept free from oily or greasy substances and should not be handled with oily or greasy gloves. Cylinder valves should be closed, and the fuel hoses bled when moving the cylinder and/or leaving the studio.
Cylinders should be marked boldly and legibly as to contents. Unlabeled cylinders should not be used. Empty cylinders should be marked as such at the time of depletion.
Cylinders should be stored in a well-ventilated area, away from heart in excess of 125 degrees F. Cylinders should be maintained in an upright Position and should be stored in an assigned area away from any danger of being knocked over- Some type of chaining or bracket is advised for maintaining and securing the cylinder in an upright position.
A leaking cylinder (or valve) or one in need of repair should be marked boldly and legibly and removed to outside and the manufacturer notified. Never test for a gas leak with a flame. Use an approved leak detector solution. These may be obtained wherever you purchase your fuel or cylinder.
Only approved hoses and connections should be used. Hoses should be color-coded: RED=fuel gases and GREEN-oxygen or air. Hoses should be replaced when they leak or exhibit any other defects.
Regulators should only be repaired by authorized and trained personnel, preferably the supplier, Regulators should not be removed until the cylinder valve is closed and the hoses and regulator drained (bled).
All welding, cutting, soldering should be done in a designated area free of flammable conditions and substances. Your shop should be equipped with an appropriate number of portable fire extinguishers.
The physical hazards involved in welding and soldering are: burns and breathing of harmful fumes. In addition, welding produces excessive infrared and ultraviolet radiation. This radiation can cause burns like sunburn to the skin and heat cataracts if eye protection isn’t worn. All soldering should be done in an area with good ventilation. Welding requires, in addition to ventilation, protective clothing, eye, and face protection.
When working with machines, do not mat loose, sloppy fitting clothing. Keep hair tied down and pulled back. Eye and face protection is advisable.
Machines and machine operators should not be positioned in aisles or walkways.
Electrically-powered machinery should be hooked up to an adequate power supply source (proper recommended voltage), and the equipment should be grounded. Wiring should be up-to-date. The studio should be equipped with a “DEAD MAN’S SWITCH” – a button to kill all power to machinery in the case of an accident or emergency.
Grinders and buffers should have appropriate safety guards and local exhause ventilation.
Casting machines should have splash guards around them. Burnout and enamelling kilns should have exhaust ventilation. Looking into a hot kiln without protective glasses or goggles can result in harm from infra-red (heat) radiation. This can cause heat cataracts.
For more specific information regarding metal saws, grinders, rollers, mills, etc., the Department of Labor has print-outs on Safety Standards by the Occupational Safety Standards Commission.
The best indication of whether or not the lighting in the workshop is ad._ equate is whether or not the workers have visual comfort.
Illumination is measured in foot candies and any light meter (like for photography) will measure this.
Machinery and equipment should (according to ANSI standards) be provided with a minimum of 50 foot candies light intensity to fall upon the general area. Fine bench and machine work and fine grinding and polishing will need 500 to 1000 foot candies. This can be obtained by supplementing general lighting with specialized lighting. When natural light is insufficient, artificial light should be provided. Try to avoid Lighting that creates glare or casts shadows over the work area.
Respirators: According to the Occupational Safety and Health Act of 1970, respirators should only be used for “special emergency situations” where local exhaust ventilation is not possible, or as a temporary measure while local exhaust is being installed- Local exhaust ventilation is more efficient than a respirator, and respirators are uncomfortable to wear and difficult to breathe through.
There are two basic types of respirators:
- air supplying-which provides a source of uncontaminated air for the person to breathe and
- air purifying-which includes masks with appropriate filters.
The first type is fairly expensive and is recommended for situations where there is use of flouride fumes and welding of toxic heavy metals and presence of asbestos dust.
Masks and filters, in air purifying respirators, will have to have different cartridges for organic vapors (solvents); acid mists; dusts; and fumes.
Respirators should be labeled that they are approved by the Bureau of Mines or NIOSH (National Institute of Occupational Safety and Health). They should be considered effective only for the particular substances they were made for. It is very important that respirators fit property and comfortably. Cartridges and filters should be changed regularly.
Please note that these are only general guidelines, not the specific information that would be needed to set up proper ventilation. Your state branch of NIOSH can refer you to a specialist in your area.
There are three basic methods of defending against airborne hazards such as dusts, fumes, vapors, particulates:
- eliminate the hazard at its source;
- protective devices (respirators, goggles).
Solutions 2 and 3 seem to be the most frequently applicable solutions for the metalsmith.
One of the most important factors in designing a studio, and one of the most frequently neglected, is adequate ventilation. Basically, there are two types of ventilation: Local Exhaust ventilation removes the contaminants at their source before they can disperse in the air and enter people’s breathing zones; General or Dilution ventilation dilutes the harmful substances with fresh air to lower their concentration to a safer level. Obviously, the first method is preferred because it is more efficient in elimination of a hazard.
Some situations that call for local exhaust ventilation: soldering, welding, brazing, annealing, acid baths, grinding, sanding, polishing, kiln operations, forge operations (when indoors), melting pitch, using solvents, and working with plastics.
A Local Exhaust system consists of an exhaust hood to trap the contaminant, a duct system to carry the contaminant outside, an exhaust fan, and, ideally, air cleaning equipment to prevent contamination of the atmosphere.
A General ventilation system replaces the air that is drawn out from Local Exhaust. The need for make-up air is frequently overlooked. If exhausted air is not replaced with fresh air, a negative pressure will develop in the room and the local exhaust system will not function properly.
There are many factors that affect the design and placement of an exhaust hood:
- The shape of the hood greatly affects its efficiency. It is most efficient to enclose the operation so that only contaminated air is drawn into the vent. On ventilation hoods located near a buffing wheel, baffle plates or lint screens are advisable so that the fans and ducts don’t get clogged.
- Vent hoods should be located so that the natural velocity of the contaminant will be in the direction of the hood opening. This would pertain to exhaust ducts by buffing wheels and fume hoods above procedures that use heat (soldering, annealing, welding) because hot air rises. Solvent vapors are not heavier than air so exhaust for these fumes should be approximately at the same level that the vapors are produced.
- The hood should be placed as close to the contaminant as possible. Velocity of the exhaust decreases sharply as the distance from a vent hood increases.
- Hoods should be located so that contaminants am not drawn through people’s breathing zones before being trapped in the hood.
- Make sure you have provided for an adequate source of make-up air to replace the air that is being drawn out, or negative pressure will result.
- The exhaust duct system should be made of materials that won’t be affected by the contaminant, i.e., exhausts for organic solvents should be fireproof.
- To insure smooth air flow, ducts should be circular in cross section with as few bends in their length as possible. When bends are necessary, make them gradual.
The type and capacity of the fan will depend on the contaminant, the toxicity of the material, the amount in the air and the required air velocity to exhaust that contaminant. All of these variables can be measured.
Regarding these and other technical problems in safety and health hazards, your local state branch of OSHA will be able to help or refer you to another agency who can help.
The best way to prevent skin irritation is to prevent skin contact with the irritating substance. The most common area of skin irritation for the metalsmith is the hands. When working with organic solvents, acids and other caustic substances, wearing rubber gloves is adequate protection. Surgical gloves will permit you to still feel the work.
Ketones will dissolve surgeon’s gloves and other poly vinyl gloves. Neoprene rubber gloves are good for acids and caustics.
Butyl rubber or natural rubber gloves can be used with ketones but not against aromatic hydrocarbons (toluol, xylol, polyester resins) or chlorinated hydrocarbons. Light cloth gloves may be used for other processes when desired. This is advised for the metalsmith who may spend long periods of time holding a vessel for raising and planishing sequences.
Leather gloves can be worn for protection during abrasive processes like grinding, sanding or buffing. Heavy leather gloves are good protection when dealing with heat from kilns, casting and hot pitch/pitch bowls.
Both the kiln and the annealing area have separate exhaust system. Note the large stainless steel bowl and splash guard, this is filled with water for quenching.
Basic common sense will usually guide the metalsmith in appropriate clothing for the studio. It is not wise to go barefoot or wear sloppy garments. Smocks are advisable for buffing and grinding operations. Leather aprons provide good protection when casting, buffing, grinding, and welding. Plastic aprons are good protection against acid splash.
Not all protective devices provide equal protection. The most protection is achieved from ear muffs. These are recommended for situations where there is a continuous noise level over 95 decibels (like using a drop forge hammer, or in a class, room with several students raising or forging at the same time, most lathes, milling machines). Ear plugs are not as effective. The best of these are the type that will mold to fit the individual’s ear. Most reference books suggest that the plugs are more comfortable. It is advisable to try and eliminate most noise at its source.
Face and Eye Protection
The face and eyes need to be protected from flying particles from machining and welding, radiation from welding and other heat producing processes. chemical splash, and acid or caustic mists.
Face masks and goggles are designed for each of the circumstances. Models are available that can be worn with or without glasses.
These devices should meet the specifications of NIOSH.