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Homemade Plastic

Step 5Mold!

Mold!
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At this point, you're ready to do whatever you want with the plastic.

It will take about two days to cure, but if you're using a mold where it cannot easily breathe, it will take longer.

One thing to watch out for is that the casein will warp when it's drying, especially if you have it rolled out into a sheet. It's best to put a weight on it. Watch out, though, because it will seep a milky-vinegary scented liquid into whatever is holding it in place. I used a heavy programming book...and it now has a funny smell to it. Awesome.

For my project, I just need to roll the casein out and let it dry.

Lay another sheet of wax paper over the casein. Use a rolling pin to spread it out. If you didn't dry it too much in the previous step, it should roll nicely, without many cracks or chunks.

Finally, I pressed it between two sheets of aluminum foil, and curved it across the bevel I'm using.

Give it a few days to dry, and it'll be ready to go. This is critical. Depending on how you wrap/mold your casein, you may find it takes more than a week to dry. Wrapping mine in foil took two weeks to get remotely dry. As is expected, the thicker it is, the longer it will take to dry.

I should also note that if you're making a flat piece like I am, the plastic will curl if you remove it from its mold before its dry. I made this mistake with this project, and ended up with a piece that was unusable because it curled.

The final product is quite rigid when it's thick (1/8 inch or thicker), moderately pliable when it's a little thinner, and brittle if it's paper thin. It's also sandable and paintable.

Go forth and have homemade plasticy fun!
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21 comments
Mar 18, 2012. 2:34 AMfqian yan says:
will mold grow on it in the process of drying?
Feb 18, 2012. 9:34 PMbillraymond says:
Are you sure this is truly casein?? My understanding is that casein is precipitated from milk by rennet, not heat. Heating whey with vinegar or other acidifier creates ricotta, which is not a cheese, as it contains no casein, but is rather the precipitated albumin and other (not casein) proteins. Galalith is made from casein and must be fixed in a formaldehyde bath; it is not moldable.
Jan 14, 2009. 1:56 PMskooterv2 says:
I play airsoft a lot and I play with some people with guns that hurt pretty bad...and this may sound weird but I was wondering if I made this thick enough do U think it could withstand some pretty hard blows like from guns shooting at 400+ fps... TYVM
Dec 3, 2011. 1:21 PMBanthablaster says:
Cool Idea, But how much milk are you willing to spend on this?

Imagine, an army of Cheese-weilding warriors!
Mar 9, 2009. 9:29 PMdrawe21 says:
Use the Cornstarch, water, and oil plastic its hard and not too brittle
http://www.instructables.com/id/Easy_Biodegradable_Plastic/
Feb 12, 2009. 10:41 PMbrandon borick says:
make a thin sheet then cover the back with glue and fabric
Jan 15, 2009. 1:43 PMskooterv2 says:
Thank you.I really appreciate u getting back to me so quickly. How would u suggest adding fabric to it? Like just adding it in randomly when molding or what? Sorry I have no idea about that. Thanks again
Jan 17, 2009. 2:49 PMskooterv2 says:
sorry another question if u don't mind. The juice that drains out of the casein and into a large pot, can u stir it and make that into plastic, too?
Jan 16, 2009. 5:30 AMskooterv2 says:
thank you And one last question if u don't mind. How thick would you recommend making it? Obviously you have more experience with casein then me. Tyvm again.
Jan 14, 2009. 2:04 PMskooterv2 says:
btw is there anything I could add to make it stronger?? And if u could e-mail me back on this I would greatly appreciate it
Jan 14, 2009. 4:29 PMcd41 says:
well this maybe the dumbest thing i ever suggested but you could try putting pencil lead(graphite) in it it is carbon and they add carbon to steel to make it harder and fabric or something but thats just what i would try
Aug 3, 2011. 7:29 PMsudanione says:
how can make it transparent
Mar 14, 2009. 9:24 PMdodo91 says:
can you add food coloring to make diffrent color plastic? i want to make this for my little brother, but white would be BORING!
Nov 7, 2009. 2:45 PMa_traceur says:
You sure can, just add it before you start the cooking process!
Jun 11, 2009. 12:21 PMi_build_stuff says:
This is pretty cool and i think im going to make a few thin sheets for airsoft myself but im going to use them as targets hopefully if its as brittle as you say it will shatter nicely.
Jul 10, 2009. 5:22 AMthefluffball says:
You should use Sugar Glass, heh - it's quicker to make. ;)
Aug 10, 2008. 3:03 AMyahoo23 says:
How strong do you think this will be against drops, bumps, and scratches? I was thinking of maybe making a case out of this for my iPod or phone. Any ideas? Or would it be easier just to buy one from a store?
Dec 14, 2008. 7:35 AMfreerunnin1 says:
make the case then to toughen it up put a couple of coats of pva glue on it, itll stop scratches and give resistance to shock for your phone :) i like cheeze :)
May 3, 2007. 3:13 PMvedran_setka says:
Good tutorial, but I cant find simmilar things. Can anyone put some links with simmilar sites or articles? I am intrested in home - made materials... Thanks
Dec 8, 2008. 5:26 PMCoffee bean says:
same here! it is better or instructables. that book has alook of kinda childish things it.
Jul 16, 2008. 1:10 PMxenobiologista says:
For the step where you strain it, and the step when you're pressing out the excess liquid, you probably should use cheesecloth. That's pretty much what it's designed for - it's pretty cheap and you can get it at many supermarkets in the section that sells kitchen utensils. Wrapping it up in a cheesecloth will also enable you to squeeze it harder and get more liquid out. For the stingy, since you're not planning to eat it, you could probably also use any old piece of cotton like an old T-shirt.
Jun 24, 2008. 5:33 AMtonymaye says:
brilliant, when you're done with using what you've made you can eat it, compost it, or give it to the dog!
Oct 25, 2007. 5:46 AMxlioilx says:
What kind of plastic is this? I think that it would biodegrade very fast as its not really a polymer this is more like making old style glue then plastic. I seriously doubt that it melts very well. The odor would be nasty like burnt fingernails. Most plastic smells sweet when its melted, or sometimes it smells like ammonia. It just depends on the type of plastic, blowing agent if any and coloring. Seriously though if you want some plastic for a project that will melt right, just find a clear container and grind it or cut it up. Then put it through your extruder that you have hooked up to the 480 volt transformer in your garage. That would work much better if you wanted to make something out of plastic. Trust me I work with injection molding machines every day. Still it is a nice harmless science project for the kids.
Jun 15, 2008. 11:46 PMmrthumbtack says:
Actually, this stuff probably would melt. According to wikipedia: "casein is used in the manufacture of adhesives, binders, protective coatings, plastics (such as for knife handles and knitting needles), fabrics, food additives and many other products." In addition casein is basically cheese protein, and that melts just fine.
Jun 23, 2008. 1:24 PMmizmercer says:
Based on my experience with casein knitting needles, they smell like leather, and you are advised not to soak them in water as they will melt. I haven't tried this myself cause they cost too much to sacrifice. Casein needles tend to be more brittle than plastic (I've snapped a few in half), but they are not as prone to causing static electricity in knitting nylon (which can happen with carbon-based plastic needles).
Jun 16, 2008. 7:14 AMbytowneboy says:
The acid keeps the caisein from melting. I cook with this type of cheese all the time. No melting.
Jun 16, 2008. 6:16 PMmrthumbtack says:
Thanks for the correction. I was just making an educated guess.
Jun 15, 2008. 5:40 AMMePerson says:
Uhhh... why do you smell the melting plastic? Won't that give you brain damage or something?
Jun 15, 2008. 7:55 AMJames (pseudo-geek) says:
yes, it does cause brain damage.
May 8, 2008. 2:32 PMcarolyn walker says:
What kind of "extruder"?
Nov 28, 2007. 6:33 PMmaker12 says:
DIY Reprap.LOL
Jun 16, 2008. 12:19 PMquntmphscs says:
Where is the final product? I wanted to see it actually made into something and hold stuff. This is EXACTLY how I made soft cottage cheese by the way, except for the pressing part. I let the "curds" drain in a cheese cloth (or similar cloth) set inside of a strainer and let it sit one hour. The stuff that drains out, the animals will drink it like crazy. The other stuff refrigerate and add whatever you want. Pepper, berries, olive oil & spiced. Eat like cottage cheese, but it's better. 1/2 gallon milk, when boiling on the sides (called scalding) add 1/4 C Apple cider vinegar and stir. Let it sit in the pot till it cools. Then strain.
Sep 25, 2007. 8:16 PMbudsiskos says:
can you melt it

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Author:Coffeebot(Coffeebot)
Just a dude who likes making things :)