science fair type question

[HAL 9000 96]

I agree with liquid resin stuff. MY dad uses it to make fake water for his train layout For more ideas, just go to a hobby store and find someone that knows about modeling.

Get a cellophane 'block' filled with air (cube shaped) and fit it inside a resin block to make for the appearance of the cube while this resin fits in.

You can find a liquid resin like this in craft stores! not sure if you're looking to get this here or the UK, but if here, this is from the Michaels website - they're a huge craft store chain:

http://www.michaels.com/art/online/display...oductNum=gc0509

cheers good idea i posted it to vito to look at

Reusable ice cubes are sealed for a reason... (safety)

If consumption is not the point then there are suitable alternatives to water ice as long as you had a chamber that pressurizes its contents enough to keep whatever frozen substance frozen independent of the actual temperature inside the chamber. As a scientific concept you can consult with the ideal gas law (PV=nRT).

consumption is not the point ,table center peices that look like the ice cubes in the link i posted and dont disapear thats all i wanted. but thanks for your imput.

I agree with liquid resin stuff. MY dad uses it to make fake water for his train layout For more ideas, just go to a hobby store and find someone that knows about modeling.

does liquid resin float? does anyone know? also i presume once i've used this resin in the moulds i will never be able to use the moulds for their original purpose again?

I noticed. My science fair light bulb went off with your OP. See my suggestion for the resin in my reply to msu.

[HAL 9000 96]

Jello would in fact melt. It needs to stay refridgerated to keeps it's shape and consistency. If you wanted to go with an edible type thing the only item that comes to mind in agar [sometimes called agar-agar]. You can find it in natural food stores as a gelatin replacement. I'd guess if you make something with enough of the agar it will keep its shape for a while in water. But, keep in mind, anything water soluble over time will dissolve [for lack of a better term] and most of the proteins and or complex polysaccharides in the edible stuff out there are water soluble - you can always just experiment too. Make a test run with the agar and see if it holds for 5-8 hours in room temp water. Agar doesn't need to be chilled to set, unlike gelatin.

ETA: edible note to water soluble stuff - obviously there are non-water soluble proteins or we would all be mush

thanks for the agar tip. will keep it in mind.

does anyone else have any suggestions of what material/compound we could use?

If you can get agarose, all you'd need is to do is make a 0.8 to 1.2% agarose gel by mixing agarose powder with water, weight to volume. Nuke in a microwave and pour into preferred mold. The material is non-toxic and fairly cheap like agar.

Likewise you can also melt agar blobs via a water bath and do the same.

[Hannah+Vito 0]

these are all cool ideas thanks for helping. we will prob try the liquid resin and agar first.

they seem the most simple and can be poured in the mould shapes we want. thanks guys.

[Niels Bohr 72]

No sweat.

A tip for plastic molding. Plastic can be morphed into another shape via temperature. However, the consistency the plastic must be constant.

[HAL 9000 96]

No sweat.

A tip for plastic molding. Plastic can be morphed into another shape via temperature. However, the consistency the plastic must be constant.

I think the resin is better... once solid its equally non-porous (therefore no inleaking) and if you have a way of making sure its not solid resin, then the air inside will help the block/cube float.

[Saddle Bronc 124]

How about dry ice?

[Niels Bohr 72]

How about dry ice?

Dry ice is CO2. When it reaches room temperature, and/or standard atmospheric pressure it goes into a sublimation step. Whereas the surface area of the dry ice slowly diminish as a function of time. Dry Ice is also commonly found in fire extinguishers. Many new fire extinguishers uses fire retardant foam that is also biodegradeable. But, dry ice will melt at room temperature.

[Ling Ling 22]

Two thoughts that come to mind...

1. Home Made Gummy Bears....there's a ton of recipes online. Not sure of exactly how long they'd last in water...but I believe there could be some types of cured gelatin that might meet your need.

2. Once I saw, at a wedding store, a kit to "mold your own #######". It was a novelty gift..but I'm thinking that whatever they use to create it, should be "water proof"

Edited October 30, 2008 by Ling Ling

[HAL 9000 96]

How about dry ice?

Dry ice is CO2. When it reaches room temperature, and/or standard atmospheric pressure it goes into a sublimation step. Whereas the surface area of the dry ice slowly diminish as a function of time. Dry Ice is also commonly found in fire extinguishers. Many new fire extinguishers uses fire retardant foam that is also biodegradeable. But, dry ice will melt at room temperature.

And putting it in room temperature liquids like water will cause lyophilization. Instead of having a floating cube you'd have gas bubbles and visible vapor hovering above the surface of the liquid. Sometimes I put a little block of it in the toilet when I get home to freak my wife out.