Ceramic Studio Safety

Respirators for Potters
by Jeff Zamek

When sweeping the studio, every potter at some point wonders, “What should I do to protect myself from the clay dust?” Imagine what’s floating around in your studio when walking or sweeping up at the end of the day. On days when direct sunlight enters the studio, it’s possible to see raw materials and clay dust in the air; but it’s the stuff you can’t see that’s the problem.

Clay is a very small hexagonal-plate-shaped particle material and can range from 100 microns (µ) to 0.1µ in size depending on the specific type of clay. (A micron is 1/1000 of an inch.) Potentially, the most hazardous particle sizes are below 10 microns, and potters should try to cut down the inhalation of particles to safe levels. Respirators are very effective at blocking particles, but no respirator is 100% efficient at blocking all particle sizes. Particles in the 0.3-micron range can zigzag through a filter (even though some get trapped) so that a percentage can pass through the respirator, while larger-size particles travel in a straight line and get trapped.

A safe and conservative approach goes a long way in protecting yourself from airborne particles-both visible and invisible. Fortunately, this area of studio safety has been thoroughly researched by industry, and potters can take advantage of the latest array of respirators.

Respirator Filters
Every respirator has some type of filter to trap particles. One of the most effective filters is a HEPA (High Efficiency Particulate Air) filter. They were developed more than thirty years ago by the Hepa Corporation. The name has since become generic and many companies now produce this classification of filters.

For many years, HEPA filters have been the standard for the industry. They have a 99.97% efficiency rating, which means they filter 99.97% of solid particles down to a 0.3-micron size. Some particles at 0.3 microns do not have enough weight to go through the filter, while particles bigger than 0.3 microns have a larger mass, causing them to travel with greater velocity to the filter. HEPA-type filters are recommended whenever heavy metals, such as, chrome, cadmium, vanadium and cobalt are in the work environment.

Respirator Maintenance
The industry standard (though seemingly inexact) for changing filters occurs when any or all of the 3 D’s are encountered-Damage to the respirator, Dirty respirators or Difficulty breathing through the respirator. While dirty and damaged respirators are self-explanatory, the difficult breathing requires some explanation. As particles contact the respirator during use and penetrate below the outer surface of the filter, some filter holes are closed, causing a caking effect to occur. This results in the filter becoming more effective in that an increased amount of holes are plugged by the incoming particles. However, at some point the heightened resistance needed to breathe causes unfiltered air to be drawn through the point of least resistance on the mask seal. Before this state is reached, the filter should be discarded.

If It Fits ...
Fit is one of the most important considerations when choosing any respirator, and two factors are essential when placing a respirator on your face. A complete seal around the face is critical in allowing no secondary air to bypass the filter. Make sure the mask conforms to your face so no outside air is drawn in while breathing. Men with beards must ensure that the mask forms an unbroken seal around their face; otherwise, shaving the area is required. The second factor is the comfort of the mask. If the particular mask is uncomfortable or heavy, and it isn’t worn on the required occasions, it offers no protection.

Two of the respirators I tested-the Willson Freedom® 2000 Series and Willson Valuair® Plus-come with diagrams and instructions on how to wear the masks, and informative videos were also available. The instructions on use and fit for the 3M 8210, 3M 8110S and 3M 8233 N100 are available from the dealer or by calling the 3M technical service number.

Respirators with higher efficiency (99.97% efficiency) filters can cause greater resistance when breathing due to the use of finer filtering materials. High-efficiency units have an exhalation valve in front to allow for easier breathing.

Willson™ Freedom® 2000 Series Disposable Respirator
The distinctive feature of this respirator is the simple straightforward design and its light weight on the face. It can be purchased in three face-piece sizes for an exact airtight fit on the face, which is a critical factor in any respirator design. The unit has an excellent P100 filter that is 99.97% effective in trapping particles down to .3 microns in size. This is the highest rating by NIOSH standards. The mask allows for eye wear and feels comfortable when I swept the studio or mixed dry glazes. However, the inability to replace the filter would be a major drawback if the potter was considering it for daily use in the studio. Replacing the entire mask and filter each time would be costly. Retail price $18.55. (Source: Willson Division of WGM Safety Corporation, product information Form No. 9121C.)

Willson™ Valuair® Plus Reusable Respirator
The easily replaceable filter extends the service life of this unit, which is a major benefit. The filter cartridges are the same ones used in the Willson Freedom 2000 series masks (P100). It also has a soft pliable face piece with adjustable straps to fit almost any face contour. From the first time I used it in my studio, it was very comfortable and there was low breathing resistance upon inhaling. Wearing eyeglasses does not prevent the mask from fitting your face. I would highly recommend the respirator for ceramics supply companies’ clay mixing operations. It can also function well in situations where there is heavy-duty prolonged dry raw materials mixing in the studio. Retail price $21.20. (Source: Willson Division of WGM Safety Corporation, product information Form No. 9601.)

3M 8210 and 3M 8110S N95 (smaller size)
Commonly referred to as a paper dust mask this is a very lightweight filter that can be custom fit by a thin metal band on the upper part of the mask. The electrostatically charged micromedia fiber attracts and holds airborne particles. Two elastic straps on each side of the mask hold it firmly against the face for an effective seal. I found the mask easy to use and lightweight on my face. The respirator was very comfortable when wearing glasses and as an added benefit had no parts to clean. It is low priced which makes for reasonable replacement costs. Studies have proven this mask to be just as effective as rubber face piece respirators. I would buy a box of the masks and replace them regularly (see Respirator Maintenance). It is rated at 95% filtration efficiency, which means the mask stopped 95% of the particles down to a 0.3 micron size. It can filter cobalt, copper, chrome, iron oxide, silica and manganese. I would recommend the 3M 8210 and 3M 8110S N95 as low-cost effective masks for dry materials encountered in the pottery studio. Retail price @ $.78 cents, box of 20 $15.67. (Source: 3M Product information sheet #3044.)

3M 8233 N100 Particulate Respirator
This is a paper dust mask made from advanced electrostatically charged micromedia fibers. It has fully adjustable straps for a secure soft fit on the face. Also incorporated into the mask is a one-way cool flow valve that makes breathing easier through the finer mesh filter. Its efficiency is 99.97%, making it one of NIOSH’s highest-rated filters. OSHA (Occupational Safety and Health Administration) recommends this type of respirator in situations where lead, cadmium, and arsenic are in the workplace. This mask would function well when mixing dry glaze materials that contain cobalt, copper, chrome, iron oxide, silica, and manganese. The higher efficiency rating and high cost per mask is not required for protection against other ceramic raw materials. It could be used in ceramics supply companies’ clay mixing operations where exposure and concentration levels would presumably be higher than in a pottery studio. I would use this respirator only if lead, cadmium, or arsenic were present in the studio. Retail price @ $6.03, box of 20, $120.60. (Source: 3M Product information sheet #3094.)

New Standards
In July 1998, the National Institute of Occupational Safety and Health (NIOSH) fully implemented new standards for all respirators (Title 42, Code of Federal Regulations, part 84, referred to as “42 CFR 84”). These new respirator specifications were designed for higher levels of protection against particulate hazards in the workplace. Respirators sold after July 1998 must comply to the new standard and “42 CFR 84” must be conspicuously displayed on the respirator package. In addition to the part 84 particulate requirements, buyers must be aware that respirators are rated and designated for other factors (i.e., N=no oil in environment, R=oil resistant, and P=oil proof). Potters typically need respirators labeled N95 (no oil and 95% efficient) or N100 (no oil and 99.97% efficient), but ratings of R95, R100, P95 or P100 would also be sufficient.

For protection against airborne particles found in the pottery studio, the 3M 8210 and 3M 8110 S N95 respirators were my first choice. All the respirators tested would meet the requirements of potters, but the 3M respirators were lighter in weight, easily replaceable and comfortable. I do not think the 99.97% vs. 95% efficiency respirators would offer a much greater degree of protection for the materials found in pottery studios or commercial clay mixing operations.

When purchasing any respirator, look for the new NIOSH codes. And always carefully read the instructions on maintenance and use of any respirator purchased, as there can be differences between each model and brand.

Most pottery studios and commercial clay mixing operations will require an N95 respirator or an N100 respirator. All the respirators evaluated would meet and exceed the respirator safety requirements of the studio potter. In addition, all units could be used in industrial applications where higher levels and longer exposure rates would be expected as compared with a pottery studio or clay-mixing operation. The higher-efficiency units rated at 99.97% efficiency (Willson Freedom 2000, Willson Valuair Plus and the 3M 8233 N100) would be very effective protection where lead or cadmium are present in the studio. However, the 3M 8210 and 8110S N95 (smaller size) rated at 95% efficiency would also meet studio requirements for safety.

Each respirator was comfortable and adaptable to fit my face, creating an effective seal. The 3M respirators, having only paper-like fibers and elastic straps, were lighter in weight as compared with the Willson respirators.

Respirator cost is not a consideration when health and safety are involved so deciding to purchase the cheapest respirator was not a factor in the evaluation.

NIOSH publishes a pocket guide listing all raw materials and their permissible exposure levels. The 3M company also publishes a similar listing on raw materials, which is updated annually. Potters can use either guide to decide the safe levels of specific raw materials in their studios. If needed, the guides can be used to determine the type and efficiency level of respirator needed in the studio. However, if the potter wanted to pursue air quality to a much greater degree, the first step would be to hire an industrial hygienist who would monitor the studio (estimated cost for the test is $100 to $180) to determine the level of particulate in the air. The information gathered from testing would then indicate the proper respirator type and filter.

Jeff Zamek, a frequent contributor to PMI, works as a ceramics consultant residing in Southampton, Massachusetts. He is the author of What Every Potter Should Know, published by Krause Publications. Contact Jeff at 6 Glendale Woods Dr., Southampton, MA 01073; or by e-mail at FIXPOTS@aol.com

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