Channel your inner Archimedes.
April 28, 2017 7:34 PM   Subscribe

What is the most efficient way of replenishing bubbles in a bubble bath?

I do bath night with my 3-year old every night, and more often than not it ends up as a bubble bath (either intentionally or from remains of the soap used for washing). I, being both an engineer and a little bit OCD, like to replenish the bubbles as they dissipate, using whatever tools are at hand--plastic cups, bath toys, my hands, etc.

It's always a fun challenge to see how efficient I can be to make the most bubbles in the least amount of time with the least effort, and I've been wondering what the best method would be and/or how to evaluate/measure methods. So naturally I thought of AskMe.

Current methods:

* pouring water out of a cup from a decent height (either a slow trickle or fast pour with maximum turbulence
* Fingers spread making rapid oscillating circles near the surface of the water
* Squirty animal producing high pressure jet, originating just above the surface at a 45-degree angle to incorporate as much air into the water as possible (produces a very fine, resilient bubble texture).

Looking for answers to whichever of the following questions tickle your fancy:

1. Given the following items: two pint-size deli containers, a few rubber duck type toys with squirty mouths, two washcloths, two adult hands, and one toddler, what is the most efficient way of restoring bubbles to a depleting bubble bath?
2. If I were to set up a scientific test for evaluating methods, what would the experiment look like?
3. Bonus points for best method to induce a bathtub-drain vortex, or to achieve laminar flow when pouring water from said deli containers.
posted by joshwa to Science & Nature (11 answers total) 1 user marked this as a favorite
Argh mods can you swap question and title? I always get it wrong...
posted by joshwa at 7:36 PM on April 28

posted by Eyebrows McGee at 7:41 PM on April 28 [1 favorite]

I am not sure what a deli container looks like but I am picturing our plastic fluff containers. Like large plastic cups. I would put a hole in one and then pump water through the hole with a second container (held so that they would stack) to get a strong pressure to get the bubbles going. I would think many tests of proper placement would be needed., but I would thing held horizontal with water stream hole at right about the surface.
posted by beccaj at 9:18 PM on April 28

Hands, because unless those are some huge squirty toys, they aren't going to be able to generate enough pressure, and are too focused in their jet stream, to make a huge number of decently sized bubbles over a broad enough area to make for a bubbletastic bath. (Such a toy might terrify the toddler or destroy your wrists, also.)

With some additional materials, you could probably rig up some kind of wheel with the deli cups, to scoop and drop water with less force, but at a continuous rate. The bubbles would be bigger than with a jet stream, and might be more likely to meander around the tub.

The towels aren't that suitable, afaict, since they're so porous, wet, heavy... You could sort of dance them across the surface of the water, but they don't move as well as hands (ie don't provide enough resistance, being more porous, and will move more slowly because of drag).

Hands can provide enough resistance to make a good range of sizes and amounts of bubbles. You can get different outcomes if you whip your hands in small circles vs large, or shake them fast across the surface of the water. It's easy to cup and undulate them to make little waves or pools to distribute the bubbles around the bath, too.
posted by cotton dress sock at 9:57 PM on April 28

I'm no bubble engineer, but my mind went instantly to some type of badminton racket-esque contraption? Or something like a kitchen whisk? Whip that bubbly water full of air with a grid of taut strings or metal wires..

I feel like the key here is something with surface area but still being lightweight enough to give the bathwater a good rapid and sustained stir.
posted by wats at 10:08 PM on April 28

Drill 200 evenly spaced tiny holes in the bottom of one of the pint-sized deli containers (1/32 of an inch in diameter, perhaps). Invert container over bathtub full of toddler and soapy water, so that holes are uppermost and mouth of container is downward, and submerge entirely.

The trapped air will escape through 200 tiny holes, and create bubbles on the surface. When the air has all escaped, return container to surface, empty water out, and repeat.

Adjust hole size and count to maximize entertainment value.
posted by the Real Dan at 11:43 PM on April 28 [2 favorites]

Punch a bunch of little holes in the bottom of a deli container, then with your hand over the holes, plunge it open side down into the bath and when fully submerged, remove your hand from the bottom.

I'd bet all the little bubbles would make a mound of foam when they broke the surface of the water -- and you could move the container horizontally as the air emptied out in order to get maximum spread.
posted by jamjam at 11:44 PM on April 28 [2 favorites]

Another way is to take a washcloth (the older and more thread bare the better) that is wet with soapy water and pull the corners together so you kind of have an air bubble and then slide your hand down the washcloth bubble forcing all the air out the center through the fabric which will create small foamy bubbles.
posted by raccoon409 at 4:33 AM on April 29

Borrow a whisk from the kitchen. Or an eggbeater!
posted by Metroid Baby at 4:45 AM on April 29

Outside of your conditions: have you considered a cheap fish tank aerator?
posted by sciencegeek at 5:30 AM on April 29 [1 favorite]

Similar to the aerator but less effective: blow into a tube or hose with one end under water. If that has the results you want, an aerator would be an improvement on the concept.
posted by asperity at 8:03 AM on April 29

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