Science Buddies: "Ask an Expert"

Hi --

My daughter and I are trying to come up with ideas on creating a model of a tsunami which illustrates how the height of the wave increases as the ocean's floor slants upward. My daughter is in the 5th grade. The model will be strictly for illustrative purposes -- no testing is required.

Of course, clay could be used to create the ocean's surface and the wave, but we were hoping to find some material that would look more realistic. My daughter thought of jello, and I can see how using gelatin (with food coloring) could possibly work, depending on the containers used and the angle chosen while the gel hardens. I had also considered the gel that looks like water, but that can be rather expensive. My nephew suggested the possibility of using a silicone product which could be built up in layers.

We would basically use a large poster or demo board to show the wave increasing in size and about to crash onto a beach. I would very much appreciate any ideas you could provide on a material to use for the water and wave.

Thank you!

Hello,

Sounds like a neat project. I'm not sure I have much help to offer, but here are a few thoughts.

Trying to find something that's clear and can be sculpted may be difficult.

Building it up in layers is a neat idea, if you can find something that cures fast enough to make that feasible. I've used clear silicon material that becomes stiff in fifteen minutes or so. If you hunt around you may find something even better. You also may have to play around to find a way to put down layers without creating visible surfaces between each, but there's probably some way to do it.

Another option might be to make a mold out of something else and then cast your fake water in the mold. You can buy expensive silicon mold making material at most craft stores, or use something like plaster or paper mache. Modeling clay covered with a thin layer of grease, styrofoam, or a big hunk of candle wax could work for the initial model.

Or, if the shape is simple, you could just carve out a negative image of it and skip the model entirely. Layers of styrofoam or cardboard, perhaps covered with a bit of modeling clay to make smooth edges could work for something like that.

As far as fake water goes, you might want to hunt around some model railroad building sites for suggestions.

Liquid acrylics would work, but they're not cheap. For example, the Clear-Lite Casting Resin available from Tap Plastics would probably work great - but at $12 a pint it's a bit steep for anything but the smallest models. (You could always try making a thin shell by painting the stuff onto the inside of a mold.)

Gelatin sounds perfect, if you can get it to survive at room temperature (or you can keep the display cold).

Best,
Erik

Thanks, Eric, for your excellent advice and very quick response! Your suggestions are well worth considering, and I will begin experimenting with them today. This site is a great source of information -- I certainly plan to visit again.

Once more, thanks for your prompt attention!