Safely break glass onstage?

[highlandmist11]

Another interesting question from a grad student. In a shootout scene onstage, is there a low tech way to break glass, a small pane in a window for instance? Some parameters include: it's supposed to break outward, (or offstage), there are supposed to be several different small panes broken in a larger window, the director has insisted on using actual tempered glass, the effect obviously needs to be repeatable and safe. If anyone has any thoughts I would love to hear them. To me this sounds more like a film application with small scale pyrotechnics but having never run across this before I am open to suggestions. thanks very much in advance!

 

[Van]

I've got a couple of ideas. None are simple. None would be REAL cheap. For what it's worth the Director should himself be shot as the use of real glass onstage for a breaking effect such as this is IMHO Stupid. Obviously has never worked in a profesional theatre as Equity would never allow an Actor onstage at the same time as an effect so described. I'd be happy to share how I'd do it safely though.

 

[Les]

Actual tempered glass is usually found in car side windows, sliding glass doors, shower doors, etc but not normally in a window pane. It is also extremely hard to break (it usually takes a sharp object such as an ax or pick).

It also breaks in to very small squares (rather explosively, I might add). Is this what the director wants?

Real tempered glass is also really expensive.

 

[jhdesynz]

I totally agree with the above. If I was acting in the show and knew real glass was being used, there would be no way you'd get me in that scene.

I would think that the easiest solution if it doesn't need to be completely transparent would be poured sugar of some kind. You could add a line inside it before it sets and use a small high speed servo or motor to "break it" (or a stage hand holding the line and pulling). Shards would still be sharp, but not on the level of glass.

 

[BrianWolfe]

Better than tempered glass would be Smooth-On's shatter plastic. Maybe cast into it a small ring of sorts that could be pull inward to make the break in the offstage direction. It would take some practice but I think it could be done. Also not cheap.

 

[highlandmist11]

I've got a couple of ideas. None are simple. None would be REAL cheap. For what it's worth the Director should himself be shot as the use of real glass onstage for a breaking effect such as this is IMHO Stupid. Obviously has never worked in a profesional theatre as Equity would never allow an Actor onstage at the same time as an effect so described. I'd be happy to share how I'd do it safely though.

Van, I would love to hear your suggestions, and yes, my first course of action is to convince said director that real glass = bad idea. However, in the event that they are set on it - I would really appreciate any suggestions you might have.

 

[FatherMurphy]

Composition of the glass aside, one trick I've heard of for breaking window panes is to use a rat trap (like a mouse trap, only larger) with a short length of monofilament and something like a 1/2" nut tied onto the bail of the trap. Trip the trap from offstage using another monofilament tied to the catch, the trap will spring shut, and the nut on the monofilament will be whipped into the window pane. Once the glass is broken, the nut falls out of sightline, leaving the audience believing the prop gun shot out the window.

You'll need to do some experimenting with the weight and the monofilament length to get the right swing and impact, and you'll have to hide the trap mechanism somehow, of course.

Another method might be a hook ended hammer lever of some sort mounted under the window, pivoting on an axle just under the sash, with a bell crank behind the flat frame to actuate it, but coming up with the right shape to hit the glass yet lay flat on the face would be an interesting exercise.

 

[Jackalope]

Yikes. If you've ever broken a car window, you know that those little pieces of glass seem to surface for quite awhile after the "breaking event"... I've found pieces of glass in my vehicle months and even years later.

 

[Morpheus]

I was involved in a show that used real glass breaking...

1940's radio hour - it was an on-stage sound FX box.
The props master (who was not a student) very carefully checked the box before we started the run, and checked the loading, and the SM and ASM's were the only ones who loaded it...

Other than that, I see no reason to use real glass on stage, seems like too much of a safety risk...

 

[cdub260]

Here's another note on safety glass. It will draw blood. I've cut myself with safety glass on more than one occasion. Never seriously, mind you but the cuts were painful and bled a bit more than I would have expected.

 

[aelfric5578]

I'm going to be working with breakaway glass resin for an upcoming show. I've watched a few videos of its use in action and it looks pretty convincing. That's the stuff Brian mentioned. I wouldn't say it's too expensive if your current plan is to use real glass. The last time I priced out glass, it wasn't exactly cheap. Especially if it needs to be replaced every show.