Category Archives: Safety

No Retractable Blades

What is a retractable knife? We have all seen them at novelty shops or with Halloween costumes. When you push the blade against a surface, it slides up into the handle. When you pull it back, a spring inside forces the blade back out of the handle. With enough speed, it appears that the knife blade is plunging into your body as someone stabs you.

The illusion they create gives many a director the idea to use them onstage in a fight scene. However, they are completely unsafe. Most larger theaters already ban them outright, but many smaller and temporary performing spaces are unaware of how these seemingly innocuous toys become deadly during a stage fight.

If the blade were to press ever so slightly against the opening in the handle, it will bind with enough pressure that the blade will not retract. When that happens, your actor is suddenly plunging a real knife into another actor with enough force to puncture their skin and even their organs. Even the knives with plastic blades will cause fatal damage.

This is an inevitable part of their design; you cannot fabricate a retractable dagger that does not bind, nor can you adapt an existing knife to avoid this problem.

In 1990 at Pentameters Theatre in Hampstead, UK, Dr. Annabel Joyce used a plastic retractable knife while playing Lady Macduff. It failed to retract and she had to go to the hospital. She fortunately recovered.

In 1998, a production of I Pagliacci in Milwaukee saw David Rendall accidentally stab Kimm Julian with a knife that failed to retract. This happened during a day of rehearsal where they had already practiced the scene a dozen times, and were actually running the fight in slow motion with the fight director. Kimm did not realize he had been stabbed at first, but collapsed three or four minutes later. He was rushed to the hospital for immediate surgery and eventually recovered, though he had to be replaced for the remainder of the show’s run.

Also in 1998, Michael McElhatton was stabbed with a retractable during a performance. Before his famed role in Game of Thrones, he was performing in Twenty Grand at the Peacock Theatre in Dublin. His character was tied to a chair and stabbed multiple times by two other actors. He wore a padded vest for protection, and the whole scene was carefully choreographed by a fight director. The show ends with his death, and the actors untied him for curtain call. When he came off, he told one of the actors, “Ow, you really punched me with that last one.” He went on stage for a second bow, then returned to the wing to tell the stage manager, “I think he winded me. I don’t feel well.” He ran out for a third curtain call, then collapsed when he returned to the wings. The blade had jammed and missed the padding, plunging into his chest and missing his heart by an inch.

These are just some of the stories that have made it into the news. Countless other injuries are swept under the rug. You can see why most theaters ban retractable knives. Rick from “Weapons of Choice” even states that insurance carriers will not cover injury claims for a show in which a retractable is used. Even if the injury has nothing to do with the knife, the knife’s mere presence is proof of an unsafe work environment. He recommends destroying any retractable knife, plastic or metal, that you find in your stock.

The University of Michigan recently banned the use of them in performances after their local OSHA representative researched their inherent danger. They also consulted with Monona Rossol, the President of Arts, Crafts, & Theater Safety, Inc., who agreed that retractable blades should be banned at schools of all levels. Perhaps the only type that could conceivably be safe is one with a flexible blade, like rubber, so when the mechanism fails, the blade can bend rather than plunge directly into your lung.

So ban and destroy your retractable knives.

Smell is Irrelevant

“This doesn’t smell bad so I don’t need a respirator.” I hear that from time to time, either from students or in online forums. Prop makers working with chemicals use their sense of smell to determine how dangerous something is. “This smells better than that, so I don’t use that anymore.” “I can’t smell a thing, so this must be safe.”

No no no. This is dangerous, and the wrong way to think about safety with chemicals.

For every chemical, OSHA sets limits as to how much you can be exposed to. They try to figure out the amount you can be exposed to while working with something your entire life, and never have adverse health effects from it. These are called Threshold Limit Values (TLV).

The first is  the time-weighted average (TWA). The TWA is meant to indicate what you are constantly exposed to at work. They measure the average amount you are exposed to over an 8-hour day and a 40 hour week. (Uh oh, we often work much more than that in theatre).

Next is the short-term exposure. or STEL. They define this as 15 minutes of exposure. And you have to have an hour break before the next exposure. And you can only have four exposures per day.

Finally there is the ceiling value. You should never reach this level of exposure, even for an instant. They also have IDLH, which is “immediately dangerous to life and health”. Instant exposure at this amount will kill or irreversibly affect your health.

So let’s look at the following chart, which has the TLVs for some common chemicals found in the props shop. You probably recognize some of these as ingredients in paints and coatings. Amines are found in many epoxies. Methyl ethyl ketone is used in polyester resin. The diisocyanates (TDI and MDI) are two of the more common curing agents used in two-part polyurethanes.

All the values are measured in parts per million (ppm), which means out of a million pieces of air, that is how many pieces are of the substance being measured (for comparison, room air has 209,500 ppm of oxygen).

Odor thresholds and Threshold Limit Values of certain chemicals

So where does smell come in? Well, every chemical has an “odor threshold”. This is the amount, again in ppm, of a chemical at which point you can smell it. This is much less standardized, because it can be hard to test and different people have different sensitivities to smell. The number is often given in a range. You can see in the chart that the odor thresholds are all over the place for the different chemicals.

I’ve pulled a few chemicals out and put them in a chart so you can see what’s happening a bit easier.


Chart for OT and TLV

Look at chlorine. The odor threshold is way below the TLV TWA. This means that even if you smell chlorine, you may not be exposed to a harmful amount. You may be able to smell chlorine all day every day and still not have harmful effects (like if you work at an indoor pool).

Now look at formaldehyde. The short-term exposure limit (the orange dot) is way down in the graph. The odor threshold is way at the top. That means you can be exposed to a harmful amount before smelling it. In fact, you will have to be exposed to three times the threshold limit before you can smell it. So if you are working with something that off-gasses formaldehyde (including many plywoods and engineered lumber, VOC-containing paints, and even some fabrics), you cannot assume you are safe because you do not smell anything.

Look at the two diisocyanates (MDI and TDI). Both of them also have an odor threshold above their short-term exposure limit. If you look back at the chart, you will see that the STEL for MDI is also its ceiling value, which is the amount you should not exceed even for an instant. And its odor threshold is twenty times higher than that. You can be breathing dangerous and even deadly amounts of MDI before you even get close to smelling it.

This is why many people suggest casting urethane parts inside a fume hood or a spray booth; even a respirator is not a reliable protector. One way to tell if your respirator has stopped working is if you can smell the outside air. But with these chemicals, you cannot smell them even when they are present in dangerous amounts. So you have no indication of whether your respirator is working or not.

Your nose is a great sensor for many chemicals, but you should never rely solely on it for your safety. You need to know about the specific chemicals you are working with and how their odor threshold relates to their threshold limit values. No more, “this doesn’t smell bad so I don’t need a respirator.”

Smell you later.

N95 Day

A little over a week ago was N95 Day, a day which NIOSH created four years ago to raise awareness for respirator-use in the workplace. It happens every September 5th – get it? N95 = 9/5 (in the US, we put the month before the day. Sorry, rest of the world).

The N95 is the most common type of respirator used in the workplace, and is probably the most common found in your props shop.

"Fit Testing the N95 Mask" by AlamosaCounty PublicHealth is licensed under CC BY 2.0
Fit Testing the N95 Mask” by AlamosaCounty PublicHealth is licensed under CC BY 2.0

Some people think the N95 is a dust mask, not a respirator, but that is incorrect. The N95 is a disposable particulate respirator, but it is still a respirator, so all the rules and requirements for wearing a respirator must be followed for the N95 as well.

A couple of things about respirators. First, you have to know when to wear the right one. If you have The Health and Safety Guide for Film, TV, and Theater, or if you have ever attended a workshop by Monona Rossol, you know that airborne hazards come in five flavors: dust, mist, fume, vapor and gas. Dust, mist and fumes are particulates, which means they are bigger than air molecules and can be filtered mechanically. Vapors and gasses are the same size as air, so you can’t just block them; you need to chemically absorb them. So an N95 can stop dust, mist and fumes, but you need a classic cartridge respirator to stop vapor and gas.

You really need to know what you are dealing with to pick the right respirator. Using contact cement produces hazardous vapors, so an N95 will do absolutely nothing. In fact, some may argue that since any respirator creates extra stress on your body, wearing the wrong type of respirator can actually be worse than wearing no respirator.

Most chemicals we use have a mix of hazards. Spray paint is a prime example; the paint comes out in a mist, but the solvents produce vapors. So you need both a particulate and a chemical respirator. Most of the cartridges you can get for your respirator have a combination filter for doing both.

One final note: you often come across shops where they are really gung-ho about eye and tool safety, but cavalier about using respirators. It’s true that if you lose an eye, it sucks, but you have two eyes, and you can still live without being able to see. A respirator protects your lungs, and if you can’t use your lungs, you’ve only got about three minutes of life left.

Captain Cutie
Captain Cutie

This is my son. He’s adorable, right? He’s lived in the hospital since he was born 14 months ago, and needs to be hooked up to a ventilator 24 hours a day to breathe. His lungs are too small to support him. Most of us take our lungs for granted and don’t stop to think that every breath we take is a small miracle.

Not being able to breathe sucks. Wear your damn respirator.

The Four Dangers of Sawdust

Sawdust happens. If you are a prop carpenter, or you do any sort of carpentry in your shop, you will produce sawdust. There’s been plenty written about maintaining the dust in your shop; that is, providing adequate ventilation in your shop,  hooking your tools up to dust collectors, hanging dust filters above larger power tools, and wearing dust masks when necessary. That’s all important, but this post is about dealing with the dust that is left. Sawdust creates four hazards:

  • Slip hazard
  • Health hazard
  • Fire hazard
  • Tool damage

Slip hazard

When you have a fine layer of sawdust on the ground, it reduces your traction. It is challenging enough to run a full sheet of plywood through a table saw. Don’t compound the struggle with slipping and sliding around on the floor. On lighter-colored floors, a thin layer of sawdust can be almost invisible and still cause slips and falls.

Health hazard

When you allow dust to hang around, everytime you drop a piece of wood or a prop, you will raise a cloud of dust. A lot of tools, especially routers and sanders, kick out a stream of air which will also blow sawdust into the air, and ultimately, into your lungs.

Fire hazard

Ideally, your shop will be set up for seperate metal and wood areas. In reality, this is not always possible, especially with larger props which cannot be moved to the metal area, or props constructed with both wood and metal. Grinding throws out hot sparks which disappear quickly, but if they find a pile of easily-combustible sawdust, they may begin to smolder and even catch fire. More dangerous is welding around sawdust. I’ve seen plenty of small fires begin from the johnny balls that fly out of a welder and roll into a pile of dust.

Tool Damage

All wood, even kiln dried, contains a minute percentage of moisture. When you turn the wood into dust, it allows the moisture to be released more easily. If you let even a thin layer of sawdust remain on your tools, the moisture will eventually begin to rust the metal parts. It makes no sense to spend hundreds or thousands of dollars on a tool with a precision-machined metal table only to let sawdust rust it away into a rough surface; especially when it takes about two seconds to brush the sawdust off.

Too much sawdust
Too much sawdust

It’s Fire Prevention Week

This week (October 6-October 12, 2013) is Fire Prevention Week. It is a good time to remind ourselves to check that we are following all the proper fire prevention procedures, whether we work in theatre, an independent shop, or at home.

Using a Fire Extinguisher
Using a Fire Extinguisher

Fires happen. We should not pretend that they are a thing of the past, or that our laws and technology protect us. Every year, Patrick Hudson of reminds us how many fires (that we hear of) happen in the entertainment industry; in 2012, there were at least 14. His posts do a good job of reminding us what the proper procedures are. And in case you think they can’t happen to you, he reminds us that the Iroquois Theatre thought the same (go read those articles now; I’ll wait). Despite its boast of being “fireproof” in a city with one of the strictest fire codes in the world, it caught fire in 1903 and killed 602 people. This was not the result of some grand failure, but rather a whole lot of little things that could have been avoided: exit doors were unmarked or blocked, lighting fixtures were in the path of the fire curtain, the scenery was not adequately flame-proofed, etc. Most of these were violations of existing fire code, rather than the lack of knowledge of how to prevent fires.

So while props people are typically not in charge of maintaining many of these things, as a member of the production team, we can still monitor them. If management or producers are pushing for unsafe practices (like covering the exit signs, or disabling the fire curtain), we can stand with the rest of the technicians so they do not need to fight the battle alone. We can keep our props out of stairwells and maintain clear egress paths through our storage areas. If we have prop fire extinguishers, keep them labelled well and far away from real fire extinguishers. Leave flammables in the flammables cabinet. If you are not aware of all the regulations and procedures to follow, Fire Prevention Week is a good time to brush up.

And if you work in your rental home or apartment (and even if you don’t), get renter’s insurance. My wife and I lived through a fire that destroyed our whole apartment building. It’s traumatizing enough without having to worry about all your stuff and where you’re going to live. You may not think you have enough stuff to make it worthwhile, but the value of all your little odds and ends adds up quick. Renter’s insurance is much more than just replacing your stuff; ours also sent movers to salvage and clean what they could while housing us in a temporary apartment. I only had to miss one day of work, which was important because I was freelancing at the time, and paid hourly. Anyone in the building without insurance had to scramble to find a place to sleep that same day, as well as take time off work to haul all their belongings out before they were damaged further or looted.

So take this week to double-check that you are doing all you can to prevent fires and are prepared to deal with one should it occur, both at work and at home. You’ll be glad you did.