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Picture of How to Cast and Polish a Pewter Signet Ring
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Hopefully this will help a few different groups of people: those of you who want to make a cool ring (and I mean that literally when you put it on in the winter), those of you trying to cast small objects in pewter and don't necessarily need an electric melting pot, and those of you who, like me, just like reading about this stuff. If I missed people feel free to correct me :)

Anywho, let's get started!

First of all, you will need:

- Safety glasses!
- A mold of whatever you're trying to cast. I prefer to use a high temp silicone rubber but you can use pretty much anything that will withstand about 600°F. A good starter project could be a design carved into a cured piece of plaster.
- Some pewter
- A blowtorch or some other method of melting the pewter
- A crucible to melt the pewter in (a steel can will work just fine on a single use basis)
- A hacksaw
- Sandpaper and/or files
- Buffing wheels and compound
- A fair amount of elbow grease, but it's not too much, and it's definitely worth it.

DISCLAIMER & WARNING: Any techniques used here are my own, and they work for me. Use at your own risk. Also, please note that this 'ible details the use of an open flame and very hot molten metal. Please ensure that no pets or small children are around to distract you or get themselves hurt. Nothing is more important than safety, so always work in a well ventilated area (outside is preferable) and it's best to have a friend close by with a fire extinguisher or bucket of water in case something goes really wrong. After the metal has solidified, it is STILL HOT. Use a pair of pliers to handle it or just wait for it to cool down before handling. Same goes for the crucible. If you choose to follow these instructions, have fun, but be safe. :)
 
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Step 1: Prepping the Mold

Picture of Prepping the Mold
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This is a fairly simple step, but the main point I need to get across here is that you want to make sure you have some kind of lubricant in your mold. In this case I'm using graphite powder (take a pencil and use a knife to scrape the lead so that you end up with a small pile of fine black powder), and I don't really have suggestions for anything else that'd work, so I'd say go with graphite powder (it's easy enough to make, anyway). If you skip this step, you may end up with castings that look like they've come from a golf ball factory.

Basically, take a brush and make sure all surfaces that the metal will touch are coated in powder. That's it! Now reassemble the mold halves and put a rubber band or two around 'em to make sure they don't fall apart when casting.

Now for the fun part!

Step 2: Casting!

It's actually not nearly as hard as it sounds. The concept is simple: melt some metal, pour it into a mold, and let it solidify in the shape of it's container. Easy, right?

Now for the specifics.

I bought my pewter a couple years ago from Rotometals. It's LEAD FREE because this will be a ring, and it's generally a terrible idea to have something that's meant to be worn on a finger (i.e. in constant contact with skin) be an alloy containing toxic lead. The blowtorch can be found at pretty much any hardware store, as can the fireproof surface I'm using (a piece of wonderboard). As for the crucible, I'm using a ceramic dish I got from a jewelry supplier but a clean, dry soup can will work as well for one or two uses. 

WARNING: Work outside, wear safety goggles, long sleeves, long pants, closed toed shoes, etc. Use any and all precautions possible to prevent you from hurting yourself or others around you. Always make sure your molds are COMPLETELY dry. If they aren't, the water will turn to steam instantly and shoot molten metal everywhere, including you.

If you got your pewter in ingot form, you're going to want to melt off a bit of it into the crucible so you don't have to remelt the entire ingot every time you want to cast a small piece (if you're using pewter shot, skip this step). I used a pair of long-handled pliers to hold the ingot while melting it, but feel free to do whatever works for you, as long as it's safe. When doing this, try to concentrate the heat of the torch on the bottom corner of the ingot. After you think you have enough metal to get a good cast, put down the ingot and pliers, and place the flame on the metal in your crucible.

Swirl the pewter around a bit while keeping the flame on it to ensure that the entire mass is molten. Now, carefully position your crucible over the mouth of the mold, steady your nerves (take a breath, recite a haiku, think about how you're gonna get to set up the giant inflatable snowman later), and pour in one smooth, consistent motion. Depending on the complexity of the mold and the thickness of the part, you may want to tap on the side of the mold a few times to dislodge any stubborn air bubbles, but experiment*. The lovely thing about metal is that it is infinitely recyclable, so if you get an air bubble you can easily melt it down and try again!

All that's left to do is pull off the rubber bands, open the mold, and pull out your casting! Now ain't that shiny... but not shiny enough. On to grinding and polishing!

*If you still have defects in your castings despite lubricating the mold with graphite and tapping on the side a few times, take note of where the bubbles are occurring. Then simply cut a few vents from there. They don't necessarily need to be too wide or deep, but again, play around with it. I kept getting little v-shaped defects near the base of the ring, close to the sprue, so that's why you see those air vents on pictures of my mold.

Step 3: Grinding and Sanding

These last two steps are the most time consuming step of the process, so be ready for 'em. 

First, cut off the extra bits (in my case the metal that filled the sprue and air vents) with a hacksaw, wire cutters, or what have you. From this point, your two main options are filing and sanding. I happen to have a lathe and a sanding pad so I used that, but you could just as easily use a file to quickly bring down those bits. 

Now comes the... "fun" part. Depending on how coarse your files were, start with an appropriate grit of sandpaper. I like to start with either 220 or 320 grit, then 320 (if you started with 220), 400, 600, and a final burnish with steel wool. This will leave you with a soft brushed look, which is quite nice in my opinion. But I still prefer a mirror polish, and I'm sure many of you do too.


Step 4: Polishing

To achieve a mirror finish, you will need two different buffing wheels (one for each compound). One will use white diamond compound and the other will use jeweler's rouge. The white diamond has a very fine abrasive called tripoli, which acts like very, very fine sandpaper. It will definitely make your part shinier, but it will still be a little cloudy. The jeweler's rouge then comes in and brings the metal to a brilliant glossy shine.

Congratulations, you're done! Now it's time to either marvel at your creation or give it to a friend :)

Hope you enjoyed it, and feel free to ask about anything I didn't explain clearly enough. Thanks for reading!
greentree891 month ago

Hey I tried this with molten copper and silver brass on the same type of mold and the mold caught fire while the molten metal solidified before pouring down completely into the the mold xD

Is there a max temperature these molds can handle?

The mold is luckily undamaged.

Can they only take pewter?

fluxplay8 months ago

It bubbles because the mould is a 2-part silicone type compound with a high temperature tolerance for low melt alloys, available from sculpture suppliers, it 'sweats'. To stop that, an easier, cheaper way of eliminating the bubbles, is simply to dust it with talcum powder first, just a tiny dusting, knock out the excess.

Dravenumbra11 months ago

It's a lovely instructable with great pictures, but what did you use for your mold? I believe it would be more instructive and beneficial to inform the readers on all aspects of your creation, but it's still great none-the-less.

FYI you can get graphite pre-powdered in the keys area of your local hardware store, and it's pretty cheap.
rachel3 years ago
I have been experimenting with casting pewter into a silicone mold and all my tests have come out more or less like your "golf ball" picture. I did not know to use powdered graphite, I will definitely try that to see if it helps.

Do you know why the pitted, cratered effect happens? I thought initially it was some mold release (from the original clay) left over in the mold, but since I made several castings, and washed it out thoroughly in between, I'm less convinced of that.
gg1220 (author)  rachel3 years ago
Hope it works!

I don't know the scientific reason why it happens, it might have something to do with surface tension or outgassing from the mold (like you were guessing before), I just know that graphite works to smooth out the casting :)
I could probably ask one of my chem teachers if you really wanna know.
actually, it's nothing to do with that. it's probably because of the air bubbles, which are in there while you are molding. you really should try tapping the mold lightly when you are pouring the pewter into the mold :D hope this helps
cool! i kind of like the golf ball one.
gg1220 (author)  mr.mountaineer2 years ago
Haha me too.
Hello, I have a couple ov question; however, please contact me on my e-mail. Reason being is because they involve pictures for a future project ov mine....and i would love your help in this project since i am considered a "newbie".

E-mail: jeffcastro_bb@yahoo.com

Please respond quickly!!

Sincerely, Jeff
BirdManJr3 years ago
Nice job, do you sell these, if so, how much per ring, I am interested in purchasing one!
gg1220 (author)  BirdManJr3 years ago
PM sent :)
mxordeath3 years ago
im interested in doing on of these, but i would like to know how you made the original mold, did you need another ring or did you have another method?
gg1220 (author)  mxordeath3 years ago
Yup, I sculpted (if you can call it that) the original ring out of polymer clay, made a mold of it, and then cast it in pewter.
Asmodeous3 years ago
Wow, thats nice. Can I just buy one off you in a size 12?
gg1220 (author)  Asmodeous3 years ago
Thanks!
If you're serious, I can probably do that for you :)
Absolutely - My email address is ardvark3@hotmail.com We can communicate thru there.

Thanks,
Todd
Looks beautiful! One question: since it is a signet ring, how would you engrave the symbol into it? Would you need a jeweler's tool or a specific technique for it?
gg1220 (author)  ElectricUmbrella3 years ago
If you take it to your local jeweler they'll probably be able to engrave it for you (they have special tools called gravers that're like carving chisels for metal), or if you have a steady hand you can go the DIY way and take a Dremel to it :)

I've personally never gotten good results with a Dremel, but I'm not at all artistic, so you'll probably have better luck than me. 
I also tried making my own graver a while back (had some tool steel blanks that I profiled and sharpened on a grinder and hammered into a wooden handle), and that worked alright. Again, having the hand-eye coordination of an artist would really be helpful if you choose to go that route.

One more thing you could do is put the symbol in it from the start. If it's a fairly simple design, you can make your clay model with the symbol you want, just make sure that all sunken areas are at least 1/16" or so deep, as you'll lose some of that depth later when you're sanding and finishing. Then your casting will be an exact replica of the original :)
I chose not to do that because the design I'm trying to (eventually) make is too complex to work that way, and since I'm making several variations upon the design I'm too lazy to make multiple molds ;)

Hope this helps!
Just to make sure I'm understanding correctly, you said (in regards to putting the symbol in from the start) that I could make a clay model of the symbol, then put it in the mold and cast the ring that way? Good idea, and what you said definitely helps. Thanks!
gg1220 (author)  ElectricUmbrella3 years ago
Sure that would be one way to do it, but not necessarily for casting metal, since the clay probably can't withstand the higher temperatures (but you never know, it might. Feel free to experiment!). If you decide to try this out, make sure you coat it in varnish or lacquer or something similar and use mold release (any type of oil or grease) on the clay piece so that it doesn't stick to whatever you're casting (and the rhyming wasn't intentional :P).

If you only want one symbol on your ring, try molding it into the original clay model. When you make the silicone mold of that model, it will capture all of the detail on the clay, including your design. That way, all the details are already in the mold and you don't have to worry about a little clay piece sliding around in there. And it's safe for metal casting.

Sorry for the confusion, I'm not very good at explaining things.
You explain just fine, and thank you for responding so quickly.
And just out of curiosity (last question, I promise), where did you find the ring to make the mold (or was it a clay model that you made the mold from)? Again, thanks for all the help.
gg1220 (author)  ElectricUmbrella3 years ago
Haha sure, I'm always on the computer xD

I actually made the original ring, because I couldn't find a commercial alternative that fit the requirements that I had. To make that, I found a piece of 3/4" rod and molded the clay around it. Then I baked it in the oven as per the directions, and while it was still kinda soft (it doesn't harden completely until it cools down), I cut a slit at the bottom and gently pried it off. Then I glued it back together, put a sprue on it, and poured the mold! :)
It's really as easy as that.
Good luck, and feel free to ask as many questions as you want!
And one more thing: I'm thinking in terms of a ring that could press a design into a wax seal - would dremels or gravers provide sufficient depth for that? It seems like casting it into the mold would be better for this purpose.
Thanks again :)
gg1220 (author)  ElectricUmbrella3 years ago
I really would recommend casting it with the symbol, since you can easily control the depth of the relief when making your clay model. Dremels might be able to do that if you have a really steady hand, and gravers are generally only really useful for small, intricate designs. So yup, you're exactly right! :)
pheenix423 years ago
Where does one obtain pewter? I love this instructable, but buying metals for casting purposes is a bit expensive!
gg1220 (author)  pheenix423 years ago
Oh boy, I know where you're coming from. Well, if you want, you can start with "cold cast" metals and such, so that you have a wider range of things you can make immediately (brass, bronze, copper, nickel silver), and with less expense per casting. You should get the look and feel of real metal with this method (I've never tried it myself, but I saw a few examples at a craft fair and they looked pretty convincing).

Now for the real stuff. I got a couple pounds of pewter from Rotometals a while back, and I just recently bought 6 pounds off of ebay. If you search for "pewter ingot" and look around, you can often find some pretty good deals there. The only thing to be careful of is that you should make absolutely sure that what you bought is lead free. These people look pretty nice, if you're wondering where to go for that.
  A bit more price than pencils but it'll save you some effort, a little does go a long way after all.   http://www.amazon.com/Panef-Corp-Powdered-Graphite-Lubricant/dp/B0016GZQ60A
gg1220 (author)  MissouriVillian3 years ago
Good point! I guess I'm just cheap ;)
Who isn't these days. It's just a question of what we're cheap on buying right.
gg1220 (author)  MissouriVillian3 years ago
Sure is :)
susanrm3 years ago
Cool. This reminds me of the centrifugal casting class I took at MIT during IAP, in which I made the most beautiful little bronze and silver items. That was more elaborate and required more intense equipment, but the principles were the same.
gg1220 (author)  susanrm3 years ago
First of all, congrats on getting into MIT! My brother's working on his college apps now and is anxious to hear back from them whenever results come out.
For your class, did you carve items out of wax, invest them, cast, and break the molds? I would love to see some pictures if you happen to have them handy :)
Also, have you seen instructions on how to steam cast? Do you think results would be similar between the two different methods?
susanrm gg12203 years ago
Thanks, but I "got into" MIT through a job application. :-) I worked there for about 10 years before I got into teaching. It was overall a great experience. IAP was so cool.

Ha - you linked to Don Norris! We used to be buds when I was active as a professional jewelry maker. I'm not sure about steam casting, but I think most professionals now use injection casting. With centrifugal casting, you got some bubbles, whereas you don't with injection casting.

I don't have photos of my things... I made a mini Parthenon and a fleur-de-lis out of bronze, a silver bell (still so beautiful), and a little silver chalice with gemstones on it that was a special gift for a friend. The chalice and bell were cast from molds made from wax I shaped on the lathe of my boyfriend at the time.

And yes, that is the process we followed.
gg1220 (author)  susanrm3 years ago
Wow, all of those sound beautiful! Your friend must've been so honored to receive the chalice.

And I guess it really is a small world! Thanks for all your time, and sorry if I've been bothering you with too many questions :)
susanrm gg12203 years ago
Thank you. And no worries about the questions. I wouldn't answer them if they bothered me. This is a learning community, so questions and sharing ideas are great! Excellent project, by the way.
gg1220 (author)  susanrm3 years ago
Thank you! I just hope it helps out people who've been having the same questions I had when I first started :)