Introduction: Metal Casting With SUGRU

Picture of Metal Casting With SUGRU


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Not to long ago, I started my ventures into metal casting. My early molds were made of plaster, but I quickly learned that silicone epoxy makes GREAT metal casting molds. Unfortunately, the silicone epoxy I was using was not designed for casting metal, and was too soft and flexible. My early silicone molds were not tough enough for lots of repeated use.

But Sugru, on the other hand, is a very durable silicone mold making material. It makes molds just as good as the silicone epoxy I used previously, except Sugru is WAY more durable, and will make molds that will last dozens of casts.

The cast quality of this skull isn't quite exactly what I'm after, but I was in a hurry. Molds need to be broken in before they with make great casts, so the first, second, or even third castings may have bubbles or vacancies. The skull in the main picture is the second cast. You shoulda seen the first one ;)

Ok, this goes without saying (but I'll say it anyway)...
Casting metal involves the use of butane torches. Butane torches have fire. Fire can burn you. So can hot metal. Got it?

If you want to cast high temp metals, just use the sugru molds for wax, then use the lost wax casting process.

There are several people in the comments arguing about fumes. They have not actually done this instructable, so they wouldn't know. Anyway, if you use solid lead free solder, there will not be any fumes. I know this from experience. Please, though, trust your own judgement and use common sense!

Step 1: What You'll Need

Picture of What You'll Need

You will need:


-Object to make a mold of

-Mineral Oil

-Tin Solder (or lead*) Make sure it's not acid core. If you use acid core, you will generate      hazardous fumes.

-Butane Torch

-Something to melt the metal in. I use a piece are firebrick carved into a bowl shape. You  could make your own out of Plaster of Paris, or a copper pipe endcap. Do not use clay or  ceramic.

-Mad Skillz

That's it!

*If you use lead, please make sure you are aware of the hazards. The MSDS for lead can be found here.

Step 2: Making the Mold

Picture of Making the Mold

Sugru is very sticky. You need it to release from the object you are molding, so oil the object in question. You'll only need a little bit of oil on the object, don't over do it and make it all drippy.

Gently mold the Sugru around the object; in this case, a small skull bead. Leave a little opening to poor the metal through (see picture two)

Put the new mold on a flat surface and let the it dry for 24 hours.

Step 3: Releasing the Object

Picture of Releasing the Object

Make an incision around the perimeter of the mold with an Xacto knife. Gently pull out the object, the Sugru could tear if you're rough... and that's something to avoid.

Once the object is released, piece the mold back together and hold it that way with a clamp (picture two)

Step 4: Casting the Skull

Picture of Casting the Skull

In my experience with casting metal in silicone, molds need to be broken in. Your first few casts will probably be failures, but the more you cast the better the mold gets.

Casting is pretty straightforward: Melt the solder with the butane torch in a crucible of some kind, and poor the molten metal into your mold.

After the metal is cool, you can unclamp and pull the cast of of the mold

Step 5: Results

Picture of Results

Now I did this because I wanted to show you that metal casting in Sugru CAN be done. If I spent more time use the mold, then my results would have been even more accurate.

Take a look at the Buddha on the intro. I Cast that using this same method. The mold I used was just more used and very well broken in.

Here are the pictures of my results:


DavidC62 (author)2017-12-11

After making the mold, I would recommend curing it at room temperature for at least 24 hours.

If you're using a 2 piece mold and you don't have a vise clamp, put the two mold pieces together between 2 small wooden boards that have been sized to fit the side of each mold. Clamp them together with C-clamps. You could also use rubber bands.

MaryK170 (author)2016-11-27

Mary K.Newman

This guide will demonstrate to you industry standards to make a modest and straightforward shape out of a silicone compound called Sugru. From this warmth safe shape one can make a Pewter throwing, for gems and such. In spite of the fact that an expert throwing will convey a more powerful and bigger shape, any reasonable person would agree for little, point by point 1-offs, I observed utilizing Sugru to be a basic and financially savvy strategy.

thorin1942 (author)2016-09-23

just starting out will sugru stand up to casting with


graphael (author)2016-03-31

Does it work with wax (sculpting wax) or not

ApexG (author)2015-03-22

Is there anyway that I could use some sort of magnetic material as I want to cast something with a magnetic metal. If so any suggestions as to which type of metal?

Curiouslilannie (author)ApexG2015-10-31

Why do you want it to be magnetic?

whereiswaldo (author)ApexG2015-03-23

no, you can't. ferrous (magnetic) metals require heat the sugru can not stand

super69lara (author)2015-09-07

Would sugru withstand molten silver?

TanjaH (author)2015-05-08

I'm looking for a durable way to cast many Gallium items. Do you have any experience with using a Sugru mold for Gallium?

kidintheworkshop (author)TanjaH2015-07-13

gallium melt in your hand or at 30 c so the mold will by used for ever

mcshannon (author)2015-05-27

I am wanting to try out casting, but would like to do it with metals of higher melting point. How hot can this handle?

jmyers3 (author)mcshannon2015-07-05

If sugru is anything like Silicone, then it will be effective up to temperatures of around 300 degrees C, the best you can hope for would be Pewter or Lead. Make sure you cast in a well ventilated area though, metals can emit some nasty gases. Good Luck!

jupiterhime (author)2014-09-14

I'm new to casting, as I'm wanting to test it out with my cosplay. Which would be a better idea to start out with? Epoxy or Sugru??

depends if you want to use metal or just normal silicone

prewon.gurung (author)2015-04-19

could you use aluminium/aluminum?

Dabbles10 (author)2015-02-06

Just a tip pitting, the little bubbles and impurities that occur in the lead casting, can be minimized if you use first a mold cleaner first. I recommend micro mark, and secondly lightly!! Powdering your mold with talcum powder. Please use a respirator mask when working and good ventilation. I cast on regular basis and worked heavily with these materials in similar molds on some pieces for a show a few years ago. Good Luck!

Also using old cans to try to cast is not worth the money you save, unless you want a casting with tons of impurities and pits also be willing to brave the cloud of toxic gasses you will be exposing yourself too.

Calleja Mark 86 (author)2011-09-05

Can anybody tell me what material should i use to make a mold for aluminium melting? I need a mold to be re-useble.

nepheron (author)Calleja Mark 862011-09-05

For aluminum you will need to use some kind of clay or oil sand. Molten aluminum will destroy sugru.

curvy77 (author)nepheron2011-11-25

doesent tin have a higher melting point? so why does aluminum destroy it but not tin?

nepheron (author)curvy772011-11-27

Nope, tin melts at 232 C and aluminum melts at 660 C.

curvy77 (author)nepheron2011-11-27

but iv melted aluminum soda cans in a tin soup can before.

josh.soanes.1 (author)curvy772014-10-01

was the soup can thicker than the aluminum

travisttt (author)curvy772011-11-28

Most "tin cans" aren't really made of tin. Most modern soup cans are made of steel, which melts at approximately 1370 C.

Sand casting? you don't say how big the mold is.

paqrat (author)Calleja Mark 862011-12-27

When the weather gets a bit warmer I plan to do aluminum casting using charcoal soldering blocks. You carve your design in one charcoal block, melt the metal directly in the mould you have created then use another block to force the metal into all the crevices of the mould. (place uncarved block on top of molten metal and push down) . You will want to make sure you have a stable work surface so that when you apply pressure you don't end up spilling the molten aluminum. Years ago, when I worked at a jewelry store I used this technique to cast gold jewelry so I think aluminum will be easy enough. I think the charcoal block would hold up to several castings but size may be a problem as the charcoal blocks I have seen were designed to do soldering on and were not overly large. If someone knows how to make a charcoal soldering block I'd sure like to hear how.

jamob (author)2013-07-19

I have 2 questions. If this works with lead and tin would it work with zinc from pennies? Just wondering because I find zinc to be safer than lead. Also what stores sell Sugru?

stoobers (author)jamob2013-09-24

Zinc melts a few hundred degrees hotter than lead or tin. Sugru probably wouldn't hold up to zinc.

Lead is not dangerous unless you dump it on yourself, eat ground lead dust or acid soaked lead, or breath excessive fumes. Probably avoid it if you are a child or are pregnant. Lead toxicity is mostly just a scam. People live their entire lives with lead bullets stuck in their bodies. You don't hear about them whining.

A zinc melt of pennies has WAY more heat in it than lead, so I would rate it as more dangerous than lead, by a long shot. HOWEVER, it pours like silver vodka so it is awesome. You really need to protect against spills, since there is so much more heat - you don't want it to drop onto sneakers or that space between your shoe and ankle.

noahspurrier (author)2013-05-14

Don't use a copper pipe endcap as a crucible or ladle. The pool of molten tin will disolve the copper walls of the cap and eventually spill out. While the melting point temperature of pure copper may be higher than your propane or butane torch, the melting point temperature of a copper/tin alloy is not. I have attached some photos that shows what happens when a small amount of tin is melted in copper. I used an ordinary propane torch with no additional oxygen.

An "iron bottom-pour casting ladle" is the best thing to use for this kind of work, but I just use a "4 inch cast iron DWV blind plug" as a crucible and ladle. I welded on steel rods for handles. DWV stands for "Drain Waste Vent". This kind of pipe is also sometimes called "Soil Pipe". Cast-iron DWV fittings are available at any hardware store. DWV fittings don't use threads. In the old days cast iron soil pipe was soldered together with big pools of lead. You can still find "plumbers ladles", which are perfect for tin. Also search for "cast-iron lead pots", "cast-iron lead dippers" and "bottom pour casting ladle".

ithica2012 (author)2012-09-24

oh sorry forgot vasaline (patroulem jelly) should not effect the casting

ithica2012 (author)2012-09-24

hi new here but try heating your mold in an oven till its bout 200 f should help a lot mettel binds up in cold molds

Rowen27 (author)2012-06-24

I realize this comment is extremely late, but in reading this, it occurs to me that the reason your castings are odd for the first few runs is likely due to the mineral oil used in the initial molding process... You might get better results if you use a degreaser in the mold before the first cast. This of course is all speculation on my part, so take it as you will... I'll be giving this instructable a try in the near future, so hopefully I will be able to get back to you with a definitive answer before long...

chamunks (author)2010-12-28

Would you not suggest using silver solder?

rickharris (author)chamunks2012-04-25

It would be cheaper to buy silver casting grains - Silver solder is not pure and will contain other metals.

It would also be very expensive.

Foxtrot70 (author)2011-07-02

I like the Instructable. I find that I can use this info readily for a new employment I am about to start which involves prototyping and fabrication of obsolete parts. I also have a silver plated wine decanter set that needs two of three replacement stopper caps, fortunately I can use the remaining one as a my pattern, wish me luck.

As to concerns by folks about fumes, some are real and not immagined. The thing is for anyone do your homework on the materials you are using. Next there are Instructables that show how to build a power ventilated work area that address these very issues. If you have an old range hood vent these can easily be converted to provide a power ventilated work area. Remember, "Nothing, is not impossible... Nothing, just takes longer to accomplish." Keep up the good work!

rickharris (author)Foxtrot702012-04-25

Be cautious - the solder is in fact largely lead with a small amount of tin added.

This would not be suitable for food use.

evindrews (author)2011-07-25

You know... I wonder if you could make key "molds" so if you lost your key to your house, you wouldn't need to buy a new key..?

rickharris (author)evindrews2012-04-25

The metal in use wouldn't be strong enough.

tinker234 (author)2012-03-03

wow thanks is there a way i could use a tin soda can as a source of metal

rickharris (author)tinker2342012-04-25

Your soda can is either steel or Aluminium!

FrozenIce (author)2011-10-29

okay so i wanna make a mold for a hotwheels car, and i only need the top metal part. how do u sugest i do it using sugru?? (yes i will dismantle it first

klayla (author)2011-08-09

So you're casting with solder? That doesn't seem like a very good idea as solder tends to pit when casted. Just curious, interesting instructable though.

larryihnots (author)2011-07-02

Simple and motivating for beginners as I !! Definately on my way to the blog now. Thanks for your innovativness !.

imBobertRobert (author)2011-07-02

small skull bead is an understatement. look at that thing! its like the size of an led head!

jimmiek (author)2010-10-18

How high a temp will this material stand before it won't work (in degrees F please, I don't do Euro measurements)

rogermyers (author)jimmiek2011-06-24

You can use google for many things including unit conversions. for instance if you type the following in to google's search bar; "204.44 degrees celcius into degrees fahrenheit" you will get the conversion. or go here for even more google awesomeness; I even use google to translate languages into english, and if you use google chrome as your web browser, it will ask you if you would like a foreign website translated in the browser...... Hope this opens up some doors for you Jimmiek! Rog

nepheron (author)jimmiek2010-10-19

A naked flam will instantly wreck the Sugru.However, the Sugru website says it can withstand 400 degrees F or so. It certainly withstood molten metal being poured's pretty tough stuff!

jwolfe-daimpré (author)2011-06-07

TIP: if you make semi-random cuts in the sugru to split it it'll go back together a lot more accurately!

stormende (author)2010-11-26

Nice ible, you got my vote.

atombomb1945 (author)2010-09-16

I do lead castings for solders as a hobby, and there are always little things that I would love to add on, but most DIY casting kits cost about $60 and will only make one or two good molds. This method is awesome. As if I didn't need yet another reason to get Surgu.

One tip for this. Where you have a space in the back of your skull for the pour to go, you can always just place a spacer there and mold around it.

nepheron (author)atombomb19452010-09-16

I'm really glad you like this!
All those lead casting kits are is an ''epoxy-silicone'. Nothing special, but at the prices they sell it for you'd think it made of diamonds or something.

Sugru is the same material as the silicone in the soldier casting kits, except sugru has a solvent that evaporates instead of a chemical reaction. The end result, in either case, is just plain old silicon.

About This Instructable




Bio: Travelling since 2013. I'm currently in Australia for some reason. --- I’m Calvin Drews, and I love to learn, experiment, invent, create, repair, and ... More »
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