The first question in selecting any knife prop is not, “How realistic does it look?” but, “What will the actor actually do with it?”
A knife that will only be worn in a sheath, drawn, carried, or displayed does not need to meet the same requirements as one used during physical action. A knife handled dynamically during a threat must remain secure in the actor’s hand, but if it never touches another performer or weapon, it need not necessarily withstand impact. A knife used for parries, blocks, disarms, or other choreographed contact must meet a much more demanding standard.
A prop suitable for one of these purposes may be entirely unsuitable for another. Selection must therefore begin with its intended use.
Purpose-Made Prop Knives
Purpose-made theatrical knives are available in steel, aluminum, rubber, plastic, and resin. Each material has advantages, but none is automatically appropriate for every kind of stage action.
- Steel generally provides the most convincing weight, appearance, and behavior. A properly constructed steel knife may be suitable for controlled weapon contact, but the fact that it was sold as a theatrical prop does not by itself make it fight-worthy. The blade, tang, handle, guard, point, and edges must all be examined.
- Aluminum knives are lighter and may be easier for an actor to handle. They can also be useful when reduced weight is important to the choreography. Depending upon their construction, however, they may bend, nick, or appear insubstantial. A nick in an aluminum edge can become surprisingly sharp, so these knives must be inspected regularly.
- Rubber knives are useful whenever the knife must come into close contact with the body, particularly during grappling, falls, and some disarms. Their flexibility can make certain actions safer, but excessive bending may look false. They also produce an obviously unrealistic sound when dropped or struck against another object.
- Plastic and resin knives can be lightweight and visually convincing, particularly when seen at a distance or carried as costume pieces. They are generally unsuitable for contact choreography because they may crack, chip, or fracture. Like rubber knives, they also tend to betray themselves when dropped.
No matter what the knife is made of, its balance must also be considered if it is to be worn in a sheath. The blade must be comparatively heavier than the handle. If the balance point lies too close to the handle, the knife will tip outward and fall from the sheath. A retaining strap does not correct the imbalance. It may keep the knife in the sheath, but the knife and sheath will simply swing upside down together.
Converting a Real Knife
A real knife may sometimes be converted for theatrical use, but only if it is a sound, fixed-blade knife of suitable construction. Folding knives, hollow-handled survival knives, decorative knives, and cheaply assembled replicas may contain weaknesses that cannot be corrected merely by dulling the blade.
The cutting edge must be removed completely, leaving a smooth, broad edge rather than one that is merely un-sharpened. The point must be rounded generously, and all burrs, sharp corners, and decorative projections must be removed. Enough blade width and thickness must remain to preserve the structural strength of the knife.
Conversion does not make a knife harmless. The finished prop is still a rigid metal object capable of causing serious injury if it is mishandled or used in unsuitable choreography.
What Makes a Knife Fight-Worthy?
A fight-worthy knife must be judged as a complete object. A thick, well-rounded blade is of little value if it can separate from the handle.
The blade and handle must be firmly secured, supported by adequate tang construction. The blade must have sufficient thickness and stiffness for the intended contact, with a smooth, broad edge and a generously rounded point. The guard, pommel, handle fittings, and decorative elements must have no sharp corners or projections.
The knife must also be large enough to read clearly from the audience. A perfectly realistic knife may disappear in the actor’s hand or become visually indistinct under stage lighting. Its weight and balance must suit both the performer and the choreography. An unnecessarily heavy knife increases fatigue and makes precise control more difficult.
No single feature makes a knife fight-worthy. Suitability depends upon its construction, condition, intended use, and the particular actions required of it.
Matching Display and Fighting Props
Sometimes the knife that looks best is not the knife that should be used for physical contact. A highly detailed or historically accurate “hero” knife may be carried, drawn, or displayed when it can be seen closely. A safer duplicate can then replace it before bodily or weapon contact begins.
The two props should match closely enough in size, shape, color, and finish that the substitution is not apparent to the audience. The exchange must be carefully planned and rehearsed. Both knives should have clearly assigned storage locations, and everyone responsible for handling them must know which prop is which.
The Practical Rule
Choose the least hazardous prop that will accomplish the theatrical purpose.
Appearance alone does not determine suitability, and no amount of preparation can make every knife appropriate for contact choreography. A knife that is perfectly satisfactory for display may be dangerous in a fight, while a knife suitable for one choreographed action may be unsuitable for another.
Both the prop and its intended use should be approved by the fight director or another person qualified to evaluate theatrical weapons.