Home-brewed plastic made from milk ...

Hi all,

... i got a book with some funny experiments made with home- and kitchen-stuff -- a bit like 'McGyver-style', my older son love it

Here i found a description how make a strong plastic and glue from milk (casein)

You have only to heat milk (not to boil!) and pour some vinegar into, so the casein separate from the whey.

When filtered and dried the casein you can press it in a mold or to any form you want and when it dry and solidify (after some days?), it forms a very strong and rigid solid -- i remember my mother talking about combs, buttons and different household-stuff made from casein when there wasn't plastic all around as today ...

For making glue (or a dispensable paste!!!) you solve the fresh made casein in hot water again and put some baking-powder into the mixture, so you get a liquid paste, usefull as strong glue.

Maybe with some additives it would be a good basis for extruding at room-temp?

I want to make some experiments with my children the next weeks, and i'll post our findings here ...

Viktor

I just made a batch up, and I'm curious to see what it's like when it solidifies. Behaves like a cross between cottage cheese and bubble foam right now. Interesting stuff!

Is this not Paneer as in from Indian cooking, except they tend to use lemon juice. The thought of RepRap curry certainly stirs my creative juices!

---

Ian
[www.bitsfrombytes.com]

Quote
Wikipedia
To prepare paneer, food acid (usually simple lemon juice or vinegar) is added to hot milk to separate the curds from the whey. The curds are then drained in a muslin cloth or cheesecloth and excess water is pressed out. Next, the obtained paneer is dipped in chilled water for 2-3 hours to give it a good texture and appearance.

yup, looks like pretty much the same stuff to me. If this is soft enough to chew, though, it seems less useful as a structural plastic...

And an update on my own batch: Apparently, this is at least somewhat edible. About half of my stuff is missing and the rest is pretty beat up. Moral: keep out of reach of cats!

... yesterday we tried it ...

I heated 500 ml milk short before boiling and poured a spoon of vinegar-conzentrate into - very fast separation of curd and whey.

After filtering we got nearly 200 grams of 'farmers cheese' - it taste as cheese too, but a little poor without salt

Then we pressed the water out and inserted the stuff in some play-doh-mold-forms.

I tried with a milled counterform from my grippers ...

After one day i tested my part - it's merely hard and i peeled it out of the form without breaking, but it stays brittle (as dried cheese).

Then i tried with heating/melting with a hot-air-gun - the part got elastic when warm and when cooled down it was somehow stronger.

Maybe it's a good idea to insert with high force and heating, so the curd melts - then it should be much stronger and faster solidified ...

AFAIK in the years from 1950 to 1960 (and earlier too) they made in Russia 'plastic'-objects from caseine like combs, buttons and tool-handles, so it should be more rigid, then my first experiments - maybe with some additives or remelting/baking?

The second experiment was the 'caseine-glue' - here i mixed the rest of the curd with some water and baking powder, so it changed to a fluid paste, which is usefull as glue and is dispensable through syringes.

Maybe when i have built my syringe-extruder i'll test with this casein-paste too - it's interesting how fast it dries when heated/sintered or if i can mix with a thixing additive, so i can stack slices without curing ...

Viktor

Very cool idea. I will have to try it at home too. The only problem I see is that milk in Houston is more expensive then Gasoline.

hmm, yes. More expensive than gasoline but maybe less expensive than CAPA? Also, much more available. Also, much cooler!

Demented

Ahh yes, and edible too.

There's a lot to be said for edible junk in 3d world countries...

Demented

Here's an article from the New York Times that describes how it was made in 1903.

Anybody know of convenient sources for metallic salt and formaldehyde?

can make plastic from starch too.. see [www.instructables.com] (step 3 has the recipe)

Fantastic post. I've been looking for this for a bit. That's great! Now we need to make a RepRapable machine to automate the process and we are really on our way to having a self-replicating machine!

Demented

Calcium chloride is a metallic salt. That's the salt commonly used to melt the ice on roads and sidewalks, so you can find it all over the place.

They did mention acetate of lead in the article and that is a metallic salt.

---

Bob Teeter
"What Box?"

Sodium Chloride (NaCl, common table salt) is also a metallic salt, since sodium is a metal

Ha ha! Then the term "metalic salt" is sort of redundant...or does it mean something else?

Demented

[en.wikipedia.org])

A salt, in chemistry, is defined as the product formed from the neutralisation reaction of acids and bases.

Ammonium can be a cation instead of a metal, and most of the anions aren't metallic.

So, while most salts are metallic, not all are.


Sometimes I wish I'd done more chemistry in school...

I made some casein (just skim milk and vinegar), let it dry overnight, and then stuck it in a ball mold in the rotomold at 350

Edited 1 time(s). Last edit at 02/02/2008 04:50PM by owad.

Caesin

I have been racking my brain trying to work out where I have come across the stuff in powder form.

Now I remember. Body building suppliers provide the stuff in big tubs as a dietary supplement (Increased protein levels) to go in protein shakes etc. (I remember using the stuff once upon a time when I had a brief flirtation with weight lifting and gyms)

This should be available in a relatively pure format as some product name or other.

I think the separated from milk variety using Lemon Juice or Vinegar may also include a quantity of other contaminants that are best separated ie milk fat and some sugars etc. Could these be contributing to the "Burning".

Where's a polymer scientist when you want one eh....

aka47

---

Necessity hopefully becomes the absentee parent of successfully invented children.

... sometimes i found milk-powder in the store - it can be dissolved with water for baby-nutrition.

With low amounts of water and heating this should give a dispensable paste too ...

Maybe this is a cheap and common source for casein-bases or could be otherwise used?

What's with mixing milk-powder, starch, water and some additives for better extrudability?

Then heating the water out and crack/activate the adhesion of starch and caseine.

This seems to be a big area for experimenting with:
- starch
- caseine-powder
- plaster of paris
- concrete/zement
- sand
- graphite-powder/toner
- talk-powder
- cutted glass-fibres
- dried pulverized grass
- wood-powder
- ....

Viktor

Reading on t'internet

The sugestion appears to be that to set the casein you need to mix/spray/pour on formaldehyde.

The result is apparently thermo set rather than thermoplastic. Possibly related to Bakelite.

Question being can we make a thick paste which has a degree of dimensional stability and dries quickly, extrude it then finalize the set by spraying/misting/soaking in/with formaldehyde.

How easy is formaldehyde to obtain ??

Most chemicals are painful to obtain in the UK.

aka47

---

Necessity hopefully becomes the absentee parent of successfully invented children.

2 lbs of casein for $23.98 in powder form, it has a flavoring agent in it, but that shouldn't cause any problems. [www.vitadigest.com]
You also might try vitamin stores and organic groceries. You can also combine digestive enzymes(specifically trypsin), strangely also available on the same website, with casein to make peptone or tryptone, which are components of bacteria culture media. And with a bit of genetic engineering you have a reprap capable of making plastic from dirt.

Casein can also be hardened with formaldehyde, but this process seems to take a long time, ie months. [books.google.com]

So casein probably isn't the best plastic to use. The ideal plastic would be based around cellulose, so you could turn grass clippings into replicating lawnmowers.

aka47 Wrote:
> How easy is formaldehyde to obtain ??

I inquired at Rite Aid and the pharmacist said none of his suppliers carried it, and that I should try an independent pharmacy.

I don't think you are going to be able to obtain formaldehyde very easily or legally in the US. Cigarettes dipped in formaldehyde is called sherm and is smoked to get hi. You won't find it but at your friendly neighborhood dope house.

Demented

Ebay and Google Products Search have it. Pretty pricey, though. Maybe the dope house would be cheaper.

aka47 Wrote:
> How easy is formaldehyde to obtain ??

Call the nearest undertaker. I presume that they still use it in large amounts.

Demented Chihuahua Wrote:
-------------------------------------------------------
...
> Cigarettes dipped in formaldehyde is called sherm
> and is smoked to get hi. You won't find it but at

Uh! formaldehyde (methanal, as it is called today) is a carcinogen. Well, cigerettes are carcinoges, too. And they smell as bad...

Anyway, assure clean and fresh air if you work with it. Or even wear mask.

In my youth I used to get it at a pharmacy.

Howie

---

--
Airspace V - international hangar flying!
[www.airspace-v.com] for tools and toys

Yeah, formaldehyde is thought to be nasty...

I would try Acetaldehyde, the next heavier aldehyde:

[en.wikipedia.org]

you can buy it online here
[www.acros.com]

I would expect the latter to be less reactive than Formaldehyde though, so don't guarantee it will work. Does anybody have a cost estimate of this plastic, all reactives included?
It's also a little unclear to me how this stuff would be dispensed. Any thoughts?

Edited 1 time(s). Last edit at 02/11/2008 04:52AM by Fernando.

Hi Fernando,

... in my second post i mentioned reusing predried caseine for glue or paste:

" ...
The second experiment was the 'caseine-glue' - here i mixed the rest of the curd with some water and baking powder, so it changed to a fluid paste, which is usefull as glue and is dispensable through syringes.
...
"

With the right mixture you have a good sticking/adhesive paste, but when drying with hot air i noticed some shrinkage, so maybe this stuff would curl too ...

Viktor

Hey Viktor.
I read your post and you are right to point out this shrinkage issue.
I have also concerns about the need of drying. This means that the water content of the paste has to be evaporated? Evaporation is quite a difficult technique to master in a even way. You can never be sure the paste dries out evenly on the surfaces and in the interior of volumes. This may cause cracks and objects with weak, unhardened interiors. Maybe this paste is better suited for flat, small objects?

Or else you could think of a baking step that would completely dry out the large object (don't use formaldehyde in this case, it would evaporate along with the water!!).
Something like this has been mentioned here before I think. But I'm afraid this would sill potentially cause shrinkage and cracks. Well, there are plenty of things to test. Sorry I can't help much here, I've got my hands full with other materials