This anecdote should illustrate a few matters of safety on a film set, as well as some budgetary implications arising from lack of preparation in the safety department.
When you need a solid scene of somebody’s arm getting hacked with a butcher knife, what’s the best prop to use? A real butcher knife! The initial plan was to swing carefully, far from our actors, using camera angles and make it look like they were closer. When we stepped into our tiny set, however, we quickly realized there was absolutely no room for handling a sharp blade, not at any speed or fashion which would produce a believable shot. It became immediately clear that we might actually injure one of our actors (or worse… the camera), and I’m here to tell you that eliminating the need for fake blood would not have made it worthwhile.
A member of the production team went out with a cast member to pick up some materials, and came back with duct-tape, cardboard, and silver spray paint. The plan to cover the sharp part of the blade was a success: the speed at which this attacker-character swings the knife blurred the effect and the knife came out perfectly realistic in the final footage. Additionally, every time our knife prop banged into our victim-character’s knuckles, arm, torso… he didn’t die! In that sense, it was a success.
However, here’s the problem:
Duct tape, cardboard, and silver spray paint are all items I have back at home in my garage, making the entire (~$13) purchase an unnecessary and irresponsible expense. Furthermore, two layers of duct tape were sufficient to cover and dull the blade, so the cardboard purchase was super unnecessary. Given that the paint didn’t stick to the blade, there was no uniformity obtained by coating the entire prop. Since duct tape comes in “chrome,” purchasing it this way would have eliminated the need for paint (by far the most expensive item in the purchase), while still obtaining the gleaming effect needed.
Careful planning beforehand would have prevented the need to waste time and resources modifying this prop, allowing us to keep our actor’s arm and the money in our budget.