Turn Styrofoam cups into METAL - Experimental metal Casting - Lost foam casting
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- Опубліковано 11 лют 2025
- In this video I experiment with lost foam casting by attempting to turn Styrofoam cups into metal. I used drywall joint compound to coat the Styrofoam and allowed it to dry before dissolving the foam with acetone and then burying the cups in sand. This can be a great way to preserve the detail on foam objects.
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Your level of patience is second to none. Use a propane torch to burn the styrofoam out of the molds, the foam will be gone and the molds will be heated.
You can get perfect casting with aluminium too, you have to bake the moulds in an oven to burn out all the styro residue, and cast the metal when the molds are still hot.
Cool! My family has an aluminum foundry. One day a guy up the street brought in a display figure of the Pillsbury dough boy. It was made from styrofoam. We covered it with nobake sand and cast it. He put the casting in his front flowerbed. You did a good job gating the cups. One trick that helps is to run a narrow hole next to the inlet. A "riser" hole to let gas out. A 3/16 rod hole is all you need.
Acetone dissolves styrofoam - it doesn’t remove it, it just leaves a varnish of polystyrene behind.
Heating the molds to ignition temperature of the polystyrene might help because otherwise you are fighting the combustion gases from burning styrene in trying to get metal into the mold.
And there is no gas vent so all the gas is trying to go up,from which you pour metal .And thats why it had so much porosity . Pouring basin and sprue are a joke.
You could try preheating the molds, it give you a little longer for the metal to flow into the gaps
kilning them would get rid of any residual styrofoam/acetone slurry as well
This is something companies actually do.
I was actually thinking that he could do as u mentioned. This would help to take out the poli styrene from the mould but again you would possibly need to be careful about the mould cracking in the heat cycle but it could help to stop the water from the joint compound from boiling so quickly with the water then also causing problems with the mould filling up easily because of the small thickness of the cups same thing really as lost pla if you don't get rid of the pla you have a lot of issues with the mould filling even
It does look like cold lap, something that I have experience of when the metal is too cold when poured, however if the metal is too hot, it's so runny it runs into the sand an you get a sandy casting ( like a casting, but with a metal/sand skin )- not good when zirconia sand is used, it blunts carbide tools like you wouldn't believe.
I think the problem with the first (shown on camera) casting of the cups was the fact that you stopped. You should continue even with there's a flash. It's normal to see stuff like that when you burn lost casting material. The concept worked, incredibly well.
To cast really thin things in aluminum with the lost form method, you have to heat up the mold. I heat up the mold to burn out the Styrofoam, then pour in the aluminum into the hot mold. With enough head to get the pressure high enough i can cast parts thinner than 1mm.
To burn out the mold i put the mold into sand in a metal container, and then heat up everything in a furnace. The the Sand will hold the heat for quite a while. This really helps to get the liquid metal to every part of a thin walled mold.
As a mold compound i use clay slurry with soap, sand and rock wool to build up thick and stable shell around the object.
Might sound weird, but Id like to see that process.
It’s always a good day when Robinson Foundry uploads!
As for improvements, it sounds like removing, not just dissolving the foam would help, slightly preheating the joint compound mold, and trying to reinforce the mold by imitating your suspendaslurry technique by pouring sand over the wet layers or even adding the wire.
Inspiring video! Thanks!
The experiment left you with some cool looking cups! I think they turned out good. Never thought I would see a nice metal Styrofoam
This was really interesting. The pewter cups look really good.
This is a really cool idea and my first thought would be to doublestack the cups. Twice the wall thickness and you could keep the styrofoam texture.
lean cup
Good Idea, I was thinking that he might do that.
I've been looking at different things to help reinforce my jewelry without damaging it by over heating. I never thought of pewter until now. Thank you for sharing.
When I saw the perfect molding of the styrofoam texture I gotta say I was impressed :)
EXCELLENT EXPERIMENT !!! In my younger days as a Die-Maker, the shop I worked at, made a pinned together Aluminum mold to inject red wax into. Then open, clam-shell like, and the wax part was removed and close the mold and do it all over again. They would then, coat those with potters slurry and add fine sand, and allow to dry, and layer it many times. Then cut a sprew hole and Fire the mold into porcelain, and pour out the wax. Then pour Stainless Steel in the sprew hole and allow to cool and drop it in a shaker bin with metal BB's and a Stainless Steel part emerges. Cut and dress where the sprew was and have a finished part in a very quick time. It turns out that those were Turrent mounts for Huey Machine-Guns. They were intricate parts. & made from Stainless Steel, it would have been hard to make those. That's kind-of what you're doing here with FOAM instead of "Lost Wax"
If you heated the molds and sand before pouring it would might reduce the thermal shock. You might make a few vents as well to prevent heated air from creating pressure inside the molds. When we did a similar process in school we did not use a coating or remove the foam, but let the metal vaporize it as it poured. If we wanted an area to be smooth we would attach some paper to the foam which worked amazingly well. We also used a green casting sand that would hold its shape if you squashed it in your fist and then opened it. You could add all kinds of textures attaching various kinds of tape and paper to the foam.
Your persistence with your project payed off. The detail of the styrofoam on the pewter looked cool before the polishing,
Used plaster drywall to cast foam successfully about a decade ago when I was first getting into metal casting. A very effective coating, cheaaap too. No need for acetone, but do need vents though.
Very informative. You changed your process from aluminum to pewter and were successful. Thank you.
Stumbled upon your channel a few days ago, and been going through your back catalogue, some amazing projects!!! Keep up the great content!
Paint the cups with some white PVA paint first, to get a layer to interface with the drywall compound. Also try diluting it further for the first coat, and using a paint brush to do a few coats first, before the more thicker coats, and for glueing the sprue on take styrene and dissolve in acetone till saturated, and use a drop of that on the sprue, then touch the cup to there, no glue residue. Acetone will have to be left in for a day or so, but cure the compound in an oven at low heat first, around 120C, so as to try to melt most of the styrene out first, holding so it is sprue down in some of the sand, so the melted plastic can flow mostly out.
Maybe if you preheated the mold to burn out the remaining Styrofoam you could avoid off gassing and fire.
Acetone will dissolve the Styrofoam but not remove it. It just turns into slime that takes up far less space
I remember reading about aluminum casting temperatures, as little as 50 or 100 degrees Celsius can make a big difference in how the metal flows....Casting something so thin the you may have needed the aluminum to be a little hotter and or needed to preheat the mold so the metal stayed hotter longer.
just a future suggestion, if you ever find the drywall compound shrinks or cracks too much, you can always make a donut shape on a flat surface, and fill the middle hole with plaster of Paris, then slowly mix the two together, the Plaster of Paris will help stabilize with the shrinkage as the compound dries by accelerating the cure time.
The drywall joint compound looks really tasty ngl
Having done this a few times now - thinner is not a good idea with lost foam. It's a great method for thick blocky things, and in those cases you don't need to melt out the foam because pouring temperature aluminum burns through it just fine as long as your maintain a constant pour with proper gating.
Thumbnail Award goes to you my guy... 👏🏆👏
Awesome work keep it up!
Lol Thank you!
FIY, you should be able to remove the joint compound with acids. There's specific types used to clean tools of concrete and other work related stuff. I used them to dissolve concrete (or at the very least weaken it) when i hole where i couldn't use a drill to cut. You can basically scoop it up with a spoon at that point.
thanks for uploading with proper captions, it's appreciated. :)
I was thinking the pewter cups would be better with a mirror finish, but I actually like that they took on the texture of the Styrofoam cups.
I gotta say, the packing peanuts look so freakin cool. The cups came out cool too. Like mini trash cans lol
Wow! You always make the best projects! I always have such fun when I visit your channel. I'm sure a lot of metal melters learn a lot from you. Excellent as usual! ☺️
Your a geniouse !!!!! Im trying some of these technics to improve my lost foam casting .
Thank you !!
What about building a couple of small diameter vents off the rim back up to the top? That would vent the air, you probably wouldn’t get the bubbling, either. Might be worth a try 🤷♂️
A bottom fed casting would be even better, allowing the gases to exit through the riser instead of flowing against the flow of metal. On some small castings, spikes are poked through the sand to touch the pattern to give a path for gasses to vent out, and the resulting metal that enters the vent can be easily snapped off.
@@joejoejoejoejoejoe4391 I cast bronze coins and thats the method. I use a flat two-part sand mold. Metal goes in one edge of the coin, and I have 2 small air vents at 1/3 and 2/3 position going up. That way, the metal can flow in and push any gases up and out the vents as it flows. It also helps when you're casting things like animals, flat, that have four legs and a tail. Put an air vent at each extremity or it won't fill completely. Those extra small "sprues" are easy enough to cut off.
You have some great NileRed vibes!!! Awesome content!
hi dude, i just wanna say thanks for making the videos that you do, theyve inspired me to try and do what you do for a living.
Many thanks
I would have never thought of switching to pewter.very clever
I love your lost pla vids and the other ones are cool too! Love your vids
Awesome job and demonstration. Now I need a Circle K Polar Pop cup, the foam ones degrade quickly when reused.
I recall large scale foundries using additives like very fine silicon dioxide to improve the flow of the molten aluminium. One of the mechanisms by which that works, is by lowering the thermal conductivity of the molten material, allowing it more more time in a less viscous state. Another option might be to use aluminium-magnesium alloys.
put 2 cups together to increase wall thickness for an aluminum cast... also add a metal tube to the top of the riser to increase head pressure
What an excellent idea! I just love your channel!!
I think I have some Pewter in my garage. Said only a few, it's certainly not me...but i was entertained. Thanks for the video.
See the videos on how small boat propellers are cast in aluminum and stainless.
Its basically a dip/coat/dip/coat buildup then kiln dried/hardened to become a ceramic of some sort… your styrofoam cup would vaporize, final clean/rinse/blow it out, then reheat (or pre-heat) to ensure its completely dry inside.
Great idea for an office something to hold pens pencils paper clips erasers or other things amazing work
Try some Ventil tubes. Like smaller versions of your feeder tube. Makes the acetone part easier and it casts much better
You should try light toping for your coating. It drys in as short as 35 mins. Will make your coating process faster. You can also mix what you need.
You never mentioned pouring temperature, although you mention melting point. The thinner the wall the more over melting point you need to pour it. If I were pouring something that thin the metal would have been glowing orange. Funny how I didn’t notice any comments about temperature either, it’s one of the most important factors in getting good results.
This is originally known as the "Lost WAX" technique. as used by artists since (at least) the ancient greeks.
a wax scipture is created, then placed in sand, then molten metal is poured which melts the wax, allowing the metal to fill the void.
A vent tube or 2 may also help with the gassing issue as well as preheating and burning off the residue before hand.
SICK! Keep up the cool vids!
I have seen others create the mold with some kind of water soluble plaster. Then heat (in a kiln) the mold to burn off the styrofoam so you have a completely empty mold.
Instead of drywall mud try Durham's water putty. It sets very hard and will form intricate molds. It sets fairly fast and even thick layers will set overnight. It seems resistant to heat but I haven't tried molten metal. You mix the powder with water to make a consistency anywhere between firm clay to pour-able liquid. Non toxic, no smell, very cheap.
it was amazing hahaha in addicted to your channel !
It's always a good idea to pre-heat your molds
Try the acetone stage with the cup sprue facing down... Jet it up in there somehow. Perfect this process, as I want to pour myself a styro-sterling cup from which to sip mohitos while I watch F1 recordings.
Very cool and original idea! I might have to try this one.
Now my lean chalice will be reusable. Thanks, Robinson Foundry!
Excellent result! I would be happy with those pewter cups :) I guess you'll have to resort to centrifugal casting to be able to "drive" most of the metal into all the crevices of the mold, if you want to repeat the test with Aluminum. Good luck!🤞
Cool that the pewter worked out at least!
I'd try doubling the wall thinkness by placeing two cups inside of each other, also creates a thicker base and higher walls, but both could be cut off if wanted.
Thicker walls get rid of a lot of problems while casting.
Drill some very small holes in the bottom of your mold.
Cover your sand/ box with thin plastic.
Add a secondary box below with vacuum.
Awesome. I would love cups like that.
Interesting experiment. Styrofoam teddy bear next!
Great idea. First attempt could work but You need to pour faster. Not from crucible but useing spoon that you'll empty in 1 seckond. But to pour so fast plaster cant be saturated with disolwed foam- to much gases.
I would double up the wall thickness using 2 cups, and removing the rim of the second, then burn out the remaining styrofoam in a toaster oven or something similar. Additionally, using The thicker walls and base would make casting easier. Also, real investment casting plaster isn't too much more expensive than the drywall mud you used and can be removed more easily by plunging into water while the mold is still hot, but the metal has solidified.
In industrial lost-foam casting, it's common to coat the foam with refractory plaster and sand in many layers, and then to burn the foam out in an oven before casting.
I couldn't help but think of an old Star Trek episode where they were drinking coffee on the bridge out of Styrofoam cups painted silver.😉☕
All the comments about burning out the film thin layer of Styrofoam residue like it would make a difference lol. Great idea with the acetone, I'm going to use that this week.
@Robinson Foundry could these cups be then used as a mold to do loss casting with aluminium and other high temperature metals?
Probably. The sand etc is what handles most of the heat.
No, drywall mud will not react to acetone, but it is radioactive. Sheetrock brand used to keep a warning label on the box about the radiation exposure hazard. A lot of people complained about it, saying they didn't want to use it since it was radioactive. So Sheetrock removed the warning and everyone was happy.
Bro that's awesome 😎
Super cool! Good job!
Mikey is one step closer to living his dream as a styrofoam cup, yo.
'dissolving plastics into a solvent' often is a lot more like 'coalescing the plastic into a big ball of goop'. With the right combination of solvents, patience and temperature I think you can get a really clean result; but id experiment with those factors in an open jar so you can test the propensity to leave globs behind.
I cast a cup in high school, but made it solid, my dad had a 19' flat bottom boat and i used it as a stand off for the cavitation plate lever with a aluminum angel iron on the other side of the stringer that i mounted the ignition toggle and a push button starter.... no key.. turned out good and never failed... Gen x Fuck yea!!!
JOINT COMPOUND!!! I should have thought of this!
I wonder if purging acetone & styrafoam remnants with a torch would have helped.
that was a great video thanks for uploading
Yeah I learned that trick about styrofoam when I was trying to spray paint some once and it just started melting. Maybe try again with different kinds of foams? Like you know couch foam and things like that you could carve
The castings looked so much better before the scotchbrite wheel. Matte looked great.
Any time I’ve “dissolved” styrofoam in acetone, it’s just melted the styrofoam down into a nasty plastic goop, which I’m guessing is what got so hung up in the thin walls of the casting. Not sure if water would affect that goop at all, like displacing the acetone and causing the goop to dry out like it does when the acetone evaporates, but maybe melting the foam down with the acetone, then flushing the casting out with a stream of water, like a garden hose nozzle or a stream of acetone if you could somehow manage that without melting the equipment, could flush it all out from in between the thin walls. A perfect styrofoam-textured metal casting would so satisfying.
Congratulations you just made napalm :D it's why the stuff flared up when he tried to cast it.
@@matthewvandeventer3632 Oh, believe me, teenage me was very, very, aware of how flammable it is... If I’m not mistaken, it’s even mentioned in the Anarchist Cookbook (which I would never, and have never, possessed nor read, UA-cam…)
I love the solid aluminum packing peanuts
Here's a tip, if you plan on drinking out of those cups (for whatever reason) avoid putting acidic drinks in them. Especially tomato juice. The acids can react with the metal and form toxic compounds. Could be a clever way of poisoning someone...
Hello.
You should definitely try Zamak alloy to do this kind of things.
It's really "pour friendly" and has amazing results compared to aluminium !
You should try and see how useful a metal version of those styrofoam food trays are.
I never knew I needed metal packing peanuts until I heard them clink together
Awesome, you could try 3d printing a thicker cup and making a mold from it, I'd totally buy something like this!
Dude! Bravo! We owe you a beer!
after the acetone clean let these mold dry and make a clean burn by heating them in a kiln and raise the temp slowly till the mold gets red hot like 1500 F for and stay at that temp for least an hour then you let the mold cool off inside the kiln naturally till they get to room temp and any traces of poly styrene will be gone in ash try that with your next mold THEN you should have WAY better result with your next aluminum pour.
An interesting idea also what's the hox on the desk since it looks lovely?
Maybe could make a wood box and cast some fittings for it as afuture project
Awesome video!
Normal People: When i see Styrofoam cups they are just Styrofoam cups
Robinson Foundry: When I look at Styrofoam cups i wonder if they can be turned into metal
Me: when I see Styrofoam cups i see food
Pretty cool. Nothing wrong with pewter.
2:56 forbidden Reese’s cups
Awesome video. Thanks
I recommend trying it again with aluminum, but stack two cups together, so the walls will be twice as thick.
Could you do a whole bunch of the packing peanuts and then give them away to viewers as a giveaway? I would love to have a couple! I think they're pretty funny
I dont know what it is but you are incredible
Great video.
I'm playing with casting and I will be trying something like this soon. Would vents for escaping gasses hve helped?
great channel :D
one-of-a-kind