[SML] Foam fire extinguishers....PROPS!

[Dougherty, Jim]

Soap on the floor is slippery, make sure it doesn’t harm clothes and or get into eyes, use only moisture-resistant actors and scenery, other disclaimers as appropriate.  Onward!

If you can dress up a shaving cream can, that's a great way to go for thick and fairly dry foam. If you want to go bigger, a pressurized water extinguisher is easily refillable and you can get replacement hoses with foam nozzles that will do a better job than the stock nozzle creating foam from the water/soap mixture in the tank.  Here's one off-the-shelf option:

https://www.firesupplydepot.com/nozzle7000a.html

Barring that expense, you could try making a nozzle to go over an existing straight-stream tip.  You want a device that will bring in more air to entrain with the mix (via a venturi of some sort) and break it up into a spray (spraying through a screen, like window screen, works).  If you contact your local FD, they might have an extinguisher to lend and show you the nozzles that they have for this purpose; the higher expansion tips usually have openings in the back to let in air and a screen front to break things up.  Here's an example:

https://www.thefirestore.com/TFT-Medium-Expansion-Nozzle

Ace Hardware online also has a tip for a garden sprayer that is supposed to make foam - I haven't used that one but it's cheap enough to try regardless ($15 or so).

The other thing to experiment with is your ratio of water to foam solution, so that you get max bubblage and don't just soak your actor.

Have fun, report back with results!

- Jim Dougherty
Middlebury College Theatre Department