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Safe metal casting for kids.

Yay! Shop class. My favorite.
  [vote for,

Even melted pewter is dangerous but what if your kids could work with metal which turns liquid at 70 C and solidifies instantly at room temperature?

Wood's metal conforms to these requirements. The difference is that the mold itself would need to be heated rather than the metal.

The child would pour granulated Wood's metal into an already heated mold until a puddle forms at the top.

Previous creations can be easily re-granulated for future "pours".

Safe, except ... https://www.flinnsc...known%20carcinogen.
[pertinax, Jun 06 2024]

"Now Benzene-free!" _22Now_20Benzene_20free!_22_20stickers
[hippo, Jun 06 2024]

PCL pellets https://www.amazon.ca/s?k=PCL+pellets
[a1, Jun 06 2024]

Field's Metal https://en.wikipedi...iki/Field%27s_metal
Non-toxic (ish) [a1, Jun 06 2024]

£153 for 500g - not bad https://www.ebay.co...=artemis&media=COPY
[hippo, Jun 06 2024]

Candidate alloys https://en.wikipedi.../wiki/Fusible_alloy
Wikipedia page with charts that can be sorted by material content as well as melting points. [a1, Jun 06 2024]

Casting plastic pellets in candy-making molds http://www.sewcando...lastic-pellets.html
Not as satisfying as working it by hand. But don't try that with fusible alloys. [a1, Jun 09 2024]

Asked on reddit https://www.reddit....al_inside_the_mold/
"Has anyone simply melted a metal inside the mold?" [a1, Jun 09 2024]

Copper crisis! https://www.cruxinv...ens-electric-future
...hopefully more real than the climate crisis. [2 fries shy of a happy meal, Jun 13 2024]


       Or you could just use lead. I'm sure the dangers of breathing in the fumes from boiling lead are exaggerated.
hippo, Jun 06 2024

       You could promote the relative safety of lead fumes by comparing them to mercury fumes. The infographics just draw themselves.   

       [+] in memoriam [8th of 7], for his known feelings about children.
pertinax, Jun 06 2024

xenzag, Jun 06 2024

       [pertinax] Indeed! The marketing for this kit will say "Now Mercury-free!"
hippo, Jun 06 2024

       You could do this with PCL plastic pellets also.   

       I use PCL pellets a lot for hand-sculpted art and utility items. I never thought of casting it in a heated mold, so [+] for you.   

       Edit to add - I included a search link to Amazon Canada for [2 fries]'s convenience, but was surprised to see how expensive the stuff is there. Lots cheaper south of 49N.
a1, Jun 06 2024

       Or you could just use wax. I really think a children's "Make your own wax cylinder" kit would sell well. It would have a mould for the wax cylinder and a supply of wax pellets to melt down, a hand-cranked thing to turn the cylinder and instructions on finding your own rose thorn for the needle, making a paper cone for the sound reproduction, and also instructions for recording and playback
hippo, Jun 06 2024

       // wax //   

       Every mateiral has its advantages and disadvantages. Closer to [2fries] goal of metal casting rather than was or plastic, maybe Field's Metal would be better, less toxic option?
a1, Jun 06 2024

       True - although while Field's metal is "less toxic", it's also not "safe for children"
hippo, Jun 06 2024

       I don't think any metal in this category will be safe for children. Conducts heat too rapidly so it can burn careless fingers.   

       PCL though - its heat transfer properties are better. I can handle it right out of its hot water bath (around 160F) without hurting myself.   

       First time I saw this stuff was years ago when a doctor made a temporary splint for some of my smashed fingers, using a perforated sheet of PCL. As soon as I got home from the ER I was one-finger typing into Google to see what the stuff was and where I could buy some.
a1, Jun 06 2024

       //I don't think any metal in this category will be safe for children. Conducts heat too rapidly so it can burn careless fingers.//   

       xenzag mentioned gallium. Melting at around 30°C (86°F), you can melt it in your hand, and the metallic form at least is pretty much non-toxic.   

       Ideally, I think you'd ideally want a slightly higher melting point, so your castings wouldn't liquify on a warm summer's day. It would probably be possible to make an alloy with other relatively non-toxic metals (maybe tin?) with a melting point of 44°C or so; that should be pretty safe.   

       Of course, you'd still need to keep it away from aluminium and steel, gallium does tend to knacker those.
Loris, Jun 06 2024

       Well crap, I didn't know it was toxic.   

       The whole heating the mold rather than making the metal a liquid first and then pouring?
Has it been done before?

       // toxic //   

       The problem is that most fusible alloys contain lead. Field's metal doesn't and might be your best choice. You're probably okay if you keep the heat to a minimum to prevent vaporization, and use a ventilating hood. Or work outside. And who cares about safety anyhow? Every shop teacher I ever knew was missing at least one finger and sometimes an eye.   

       // Pouring pellets into a mold .. has it been done? //   

       Don't know but admittedly I didn't search very hard. I did find an example of someone trying something similar with the plastic I mentioned (link) - but they didn't like the result. Took too long to melt through because PCL doesn't conduct heat very well - but I think metal would work better.
a1, Jun 09 2024

       Afterthought - you're need a shot tower to "re-granulate" used items back into pellets. Or even to turn ingots into pellets for first use, if it turns out those are cheaper to buy initially than pellets.   

       I'm beginning to think melting metals in a mold has been done before, but not exactly as you've proposed for kids' shop class. And the info I've found on it hasn't been on low melting point allows.   

       How are you going to heat your mold?
a1, Jun 09 2024

       You'd probably need to melt the material before it went into the mould anyway. Otherwise, there will be too many bubbles and the cast quality will be shite.   

       Heating the mould for metal casting is I think standard for many processes. I've seen people do it in amateur small-scale casting videos on youtube.
Loris, Jun 09 2024

       // Heating a mould before using it is I think standard for many processes //   

       Aye, but that's mainly to improve flow and keep the melt from cooling off too fast. Not (usually) to initially melt the casting material.
a1, Jun 09 2024

       If you have pellets, there is air between them.
Bubbles are the bane of casting things. You really don't want to be trying to deal with air inside your mould - especially not when it's hot and full of liquid metal.
Loris, Jun 09 2024

       // You really don't want to be trying to deal with air inside your mould - especially not when it's hot and full of liquid metal. //   

       But that's the beauty of this idea. Field's Metal doesn't need to be very hot to melt, so what doesn't work with other metals might work here. And whole thing will stay melted for a long time - rather than starting to cool as soon as poured. As the pellets melt they'll flow to the bottom of the mold and air will escape at the top. Might be able to agitate the mold to assist with that too - again something that's easier and safer at 150F than higher temps.
a1, Jun 09 2024

       Once you start shaking something heavy and hot enough to cause third degree burns around, I'm not sure 'safe' is the appropriate word.   

       n.b. what does third-degree burn mean?
This text is provided as a courtesy to the squeamish, last chance to look away... First degree is 'superficial', appears red with blisters, healing time 5-10 days. Forth degree is 'black and charred'; does not heal. Third degree is a full skin thickness burn, healing is prolonged and incomplete. This is a little more padding text.
Loris, Jun 09 2024

       I reckon [2fries] would have to teach basic safety procedures to his students. "Don't shake this enough to slosh the melted metal on you," that kind of thing. Some sort of vibrating plate on the work bench may do the trick.   

       Field's metal melts at 144F, a bit hotter than I would consider safe. Some other fusible allows can melt at lower temps but they all have lead in them and are considered more toxic.   

       Definitely want to try this with PCL, as I know by experience I can work it bare handed in melted form.
a1, Jun 09 2024

       You guys are the rocket-surgeons...   

       ...I just relay brain-farts which may or not be viable.   

       I'm glad this one seems to maybe have a touch of merit.
They are talking about making citizens sort alcoholic and soda-pop aluminum before refund...
...I would just a soon solar-smelt all of that aluminum down to ingots and bury it.

       I've also got about a thousand pounds or so of copper to be recycled.   

       Should I smelt and sit on it?   

       I wondered what you guys thought?   


       What used to be a Simpsons Sears and a Safeway collapsed and I now own them and had to clean them up by hand. They were built in 1984 and "everything" back then was copper.   

       If you can put yourself in my shoes I would really appreciate feedback.   

       This whole fake-it til you make-it thing is over-rated.   

       Some feedback from people who actually 'know' history...   

       ...would be good.   

       I'm about as out of my depth as I've ever been and, any advice is appreciated.   

       Just got here, and I don't have much to contribute, but as John Varley said "Mumble".   

       I envy your copper collection - smelting takes energy though. Large pieces could be used to build stills - And you should read up on sand casting also, I've got sand casting fantasies about making sculptures that I'll probably never realize, such as using firearms or fish to make molds. For that matter, if you are feeling creative, soldering or welding scrap in interesting shapes could be fun.   

       And, of course, selling scrap metals for cash is nice. Depending on how corroded your stash is, prices will vary.
normzone, Jun 13 2024

       //Should I smelt and sit on it?//   

       Short answer, I'd say no.   

       If you want to hold commodities as a hedge against inflation, then you would probably be better off with more liquid commodities (that is, ones that are easier to buy and sell, because you can find more buyers and sellers for, say, gold, without having to drive a truckload of stuff to Chicago).   

       If you want to hoard stuff in preparation for the collapse of civilisation, then conversion into ingots is probably not going to add much value, because you're going to need to reconvert it later to some other form.   

       If you want to speculate on the future price of copper and aluminium, with a view to selling later, then that price depends on how much governments around the world prioritize decarbonisation; the harder they try to decarbonise, the higher goes the price of Cu and Al, but then you're gambling on the results of various elections, and "unknown unknown" future events and, while you're waiting for the price to go up (it's currently going down), your assets are not yielding any income.   

       So, I'd suggest
1. making things (see suggestions from [normzone]), because making things is something you can probably do better than most people. And
2. if you have too much material ever to use up that way, then I'd suggest trying to identify other people within a convenient distance of where you live, who also make stuff out of metal, and seeing what sort of deals you can make with them. Whether or not you make much money, those relationships might come in handy later. And then
3. if you still have a whole lot left over, see if you can find someone you trust in the local scrap metal market.

       I don't know if that advice is of any use to you - but, since you asked for advice, that's how it looks to me.
pertinax, Jun 13 2024


       There is talk of a copper crisis looming, [link], so I do believe I will keep every wire longer than 50 feet and decouple any intact pipe.
The remainder I will sell for scrap later when it equals the price of one ounce of gold.

       I do like the idea of making a sculpture from it though.
It would turn all green like the Statue of Liberty.
I once took a year and built a bobble-headed dragon hanging from a string. I would someday like to recreate that from stronger materials than the first time.
The original was made from tin and its head bobbled from the first neck segment which bobbled from the second neck segment... etc. I think there were five or so. The wings actually, flapped counter balanced by the feet. The feet held a tea-candle in a blue glass holder. The tail acted like one of those plastic snakes which strike outwards when tilted slightly.

       I made a heat engine of a bi-metalic strip from a thermostat on a teeter-totter to contract when entering the flame of the candle and strike the cords inside the body which would cause it to appear to come to life when the candle was lit.   

       I wasn't able to build it small enough to fit inside the sculpture but picture a reflective metallic dragon with orange and blue ripples playing over its scales as it languidly flaps while it slowly looks around the room in all directions, tail swishing serenely behind.   

       It was pretty cool before our postal service pulled an Ace Ventura and destroyed it.
"Gotta package people!"

       // looming copper crisis //   

       You just wait until the looters try to nationalize the mining industry. Look at what happened with the d'Anconia Copper mines!!!!!!   

a1, Jun 14 2024

       Gut reaction?...   

       This one I buy. I told you guys that precious metals were next on the auction block.   


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