New cadidate for 3-D printing.

If I can direct your attention to [www.flickr.com] for a moment, I am hoping someone here can figure out which company makes this material, and whether the material itself is protected by patents or other burdens.

In short, the stuff is a salt-water hardening polymer that glows in the dark. While the glowing function isn't that interesting, the viscosity change is. If the material is easy to produce or procure, it might be interesting for someone who wanted to make a more toy-like fabricator. (I consider it to be in our interests for a toy company to make a fabricator of some type, since toy-market economies of scale mean that a cheap hackable platform wil become available for anyone wanting to make a RepStrap.)

EDIT: The stuff seems to be a variation of Be Amazing's "Insta-Worms" (http://www.beamazing.com/ProductDetails.asp?prodid=16). I'm guessing that this stuff is not patent-protected.

EDIT 2: And we have a winner! The "Worm Goo" is nothing other than the darling of the Molecular Gastronomy movement, Sodium Alginate! [www.stevespanglerscience.com] has a rough explanation of what's going on.

Edited 2 time(s). Last edit at 02/19/2009 03:07PM by mycroftxxx.

So, the question would be whether anyone who is good at mechanics wants to figure out a delivery system for a thread of sodium alginate into a bed that is slowly being lowered into a dish of calcium chloride. It's a good shortcut to making a room-temperature fused deposition modeler.

It looks like jelly, is it possible to get it hard enough to make solid objects?

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[www.hydraraptor.blogspot.com]

If sodium alginate is left in contact with calcium chloride long enough in a water bath, it will solidify. I am not sure how strong or sturdy the resulting structure will be, though.

SODIUM ALGINATE! You can buy big bags of the stuff from art stores real cheap, it's used for making molds or something of that nature. Looks like we might have a keeper here...

I've been to a seminar about casting, which included a section about using Alginate to make molds from people.

It can be made to set pretty fast (some seconds) in air by mixing it strong with warm water.

What they told us was that it is short life (hours) and dimensionally unstable, because it's a water gel: A solid matrix filled with water. You can make it harder or softer by changing the proportion of water, but there's no way to stop the water evaporating off, and once that happens, it turns to dust. Also, it has a low rather tear strength.

So I don't think it would be a good RP material in itself.

On the other hand, it could possibly make a good support structure, if we could build an extruder that would mix it on demand. I have to say that doesn't sound easy, though. :-/

Leo

Hi Leo,

what's with replacing the water with waterglass for mixing Alginate?

Waterglass shrinks some percents when the embedded water evaporates, but then forms a hard body out of silicate.

Search the forums for "waterglass" - i made some suggestions and experiments with ceramic-slurries, but it can be used for other mixtures too ...

Viktor

Sounds like an ideal support material indeed it it will disintegrate by itself after a bit.My only concern is if it will bond to to itself so that you can lay multiple layers of it. Mixing should be fairly easy I would think considering it's a liquid and a powder, gravity should suffice to pull them down into a mixing chamber, and extrude from there, or have one of the two extruded and have the other material supplied by a spray nozzle once it comes out of the deposition nozzle, assuming the reaction happens fast enough for that to be viable.

Take a bath of vinegar and drip a droplet of sodium silicate. it hardens instantly.
Any acid will do - lemon juice, ascorbic acid(vitamin C), mineral acids, whatever.
Sodium silicate is very common and cheap, sold in paint shops as "liquid glass" or "water glass", sometimes as glue.
It will not glow but it hardens well and the properties are easy to adjust by adding water.