Liquid that hardens fast on a chosen moment

[bartatphysics]

Hello to all,

I am new here, with almost the same question like on this thread:
https://www.physicsforums.com/showthread.php?t=310911


A question for an artistic project:
I am searching for a not too dangerous (glossy white) opaque liquid that hardens very fast on a chosen moment, but is not adhesive.

It have to stay liquid till i decide that it have to become hard.
The process of hardening have to be very fast, in a few seconds or in a minute, if possible.

It have to be opaque and ideally it have to be glossy white, density a bit more then water.

I am thinking for hardening with Ultraviolet light that is switch on a moment for few seconds.
Or other possibilities are more then welcome.

Thanks for tips & tricks, searching already for a year.
Bart

 

[mfb]

I moved the thread to mechanical&chemistry engineering, that fits better than "General Discussion".

How large is the volume that has to get solid?
A supercooled liquid could be possible, there are many videos of this effect on youtube (one example. I think you can make the water (or whatever liquid you use) opaque with some additional ingredients.

 

[RocketSci5KN]

For a one time transition, but may not work for bulk liquids, search under Rapid Prototype liquid resins - they will cure under a UV laser, but likely only for a thin film. There are also some UV curable epoxies, but you'd want the type that cure the bulk of the material once any part of it is exposed to UV (Hg UV lamps are typically used for this). For a fast (millisecond) transitioning material, and 100% reversable, search Magnetoresistive and Magnetorheological materials (IIRC the Lord company makes these). They are ferrite loaded liquids, which become 'solid' when exposed to strong enough magnetic fields. They are only available in a grey color.

 

[bartatphysics]

Thanks for fast and interested replies!

@mfb: Good to move the thread.
The volume will be a kind of blob, let say minimum 10cm and maximum 30cm diameter. @rocketsci5kn:
It doesn't have to be UV, but that seams to me a good solution.
How strong has to be the magnetic field?
Don't find to much about that company and their products?

 

[etudiant]

A blob 30 cm on the side is not going to harden quickly. Even 10 cm is a real stretch.
The UV cured resins used in dentistry are usually a few mm to a side and they cure irreversibly.

The magnetoresistive materials are not cheap and have pretty severe constraints afaik for shape and size, including that the magnetic field has to be somehow induced, so the blob will be confined within the apparatus.

Do note that there are supersaturated solutions that will crystallize out into pretty arbitrary shapes, set by the container. Some of these solutions are non toxic and the process is reversible in instances simply by heating the material.

 

[RocketSci5KN]

You might also look into Sodium Acetate: http://www.howstuffworks.com/question290.htm
Easily available on ebay. This would harden quickly for any size object, but be careful of the heat released.

 

[RocketSci5KN]

http://www.lord.com/products-and-solutions/magneto-rheological-(mr).xml

Search this term on youtube also for interesting videos. Not sure of the magnetic field strength needed - grab a datasheet and find out...