Lost-wax gold casting advice??

The #1 community for Gun Owners of the Northeast

Member Benefits:

  • No ad networks!
  • Discuss all aspects of firearm ownership
  • Discuss anti-gun legislation
  • Buy, sell, and trade in the classified section
  • Chat with Local gun shops, ranges, trainers & other businesses
  • Discover free outdoor shooting areas
  • View up to date on firearm-related events
  • Share photos & video with other members
  • ...and so much more!
  • Collector98

    Active Member
    Jan 18, 2015
    271
    Hello, there seems to be a wide variety of knowledge on here, so configured I'd ask! Does anyone here have experience with lost wax casting? If so if love to hear your tips and tricks! Thanks!
     

    toppkatt

    Ultimate Member
    Apr 22, 2017
    1,185
    U of MD school of Dentistry taught it back in the 80's . They might still so check with your dentist?
     

    Mitral

    Active Member
    Sep 6, 2015
    175
    Calvert
    I did it professionally years ago before I discovered construction was much more lucrative what do you wanna know
     

    Collector98

    Active Member
    Jan 18, 2015
    271
    Looks like I've come to the right place! I'm planning on making a ring, not to use for a while lol, but I know it will take me a while to figure out. My plan is to finalize the ring wax model, make a silicone mold of it so I can remake the wax part as many times as needed, and then finally make a plaster mold for the actual casting. I would like to keep the project reasonably priced, but I want to make it right. I'd like to use an oxy-acetylene torch to melt the metal in a crucible and them pour into the plaster, in your opinion, would this produce good results? The hardest part for me, I believe will be stone setting, but I'm up for the challenge. I'll attach a couple pics of the wax-model progress. Any tips on how to improve the wax model would be greatly appreciated! I think those are my main questions, so I'm really looking forward to your help! Thanks!
     

    Attachments

    • 20200624_161201.jpg
      20200624_161201.jpg
      30.6 KB · Views: 297
    • 20200624_172039.jpg
      20200624_172039.jpg
      18.8 KB · Views: 288

    Mitral

    Active Member
    Sep 6, 2015
    175
    Calvert
    Traditionally the wax model is cast to make the mold
    Vs molding off the wax. The rubber is flexible and wax is brittle. So I would get your best wax and cast in silver or something like bronze. And then use that as your “ base “ model in wax to tweak
    The casting process is really equipment intensive
    The plaster “ investment “ must be bubble free and burned out to create the place for the molten metal to replace. It’s traditionally done with a spring loaded arm that literally throws the molten metal into the space created. By melting the wax out of the investment.
    You may wanna explore hand building what you want
    Via forming the metal and soldering with the actual gold. If practice is what you want I’d suggest silver to make your model it works a lot like gold
    And is easier to “ start over “ with less $$ in materials.
    To cast willl require.
    An oven , a casing machine , investment , crucible to pour into and base and spruce system
    It’s made for mass manufacture vs a one off.
     

    Mitral

    Active Member
    Sep 6, 2015
    175
    Calvert
    You can always make your best wax and have it cast by others. And request a mold be made.
    It’s less expensive than all the equipment.
    But if ya have a mold to get a wax off it you will need a wax injector to fill the mold.
     

    Occam

    Not Even ONE Indictment
    MDS Supporter
    Feb 24, 2018
    20,239
    Montgomery County
    There's a reason this is a profession. Casting fine jewelry is not an easy process. Doing it right can involve centripetal spinning machines, or vacuum devices, etc., to avoid the countless tiny flaws, pitting and other casting artifacts that will show up when less skill or the wrong gear involved.

    To make it work, you'll need a lot more gold than will ultimately show up in the ring. Casting houses don't care, because they continually recycle the scraps and tiny leftovers. Working on your own, you're going to have a lot of money tied up in gold that won't end up part of the ring.

    Then there's finishing the cast material - which, if you want a fine polish, is a discipline all to itself (in a commercial jewelry studio, that's sometimes something that one person does, all day long, because that's the thing they're good at). You will lose more material as you polish - and probably won't have the dust/particle trapping and filtering that goldsmiths use to prevent losing gold.

    Then (assuming you got the size right, and have taken into account the fact that the cast item will not end up the same size as the original wax carving, and that finishing will remove material, changing the size in the other direction), you've got stone setting. That's a very fussy process and takes serious skill and practice just to make the mount secure enough to avoid losing the stone, never mind the aesthetics. Pros work under what amounts to a stereo microscope, and have to know exactly when or how to anneal the prongs as they work harden, exactly how to handle sturdiness vs visually pleasing results ... and it's not at ALL unusual to trash the ring and have to start over. Which is why pro studios have people who just set stones all day long.

    This is NOT me trying to talk anyone out of an earnest interest in having a hand in making something beautiful and emotionally meaningful. I get it! I also have a wife that does this stuff, and have seen the thousands of hours that go into producing even just vanilla pieces that don't look amateurishly executed.

    But you can send your wax carving to a casting/finishing house, and find someone to finish the piece and set the stone ... and get very good results for a fraction of the cost (even if your time isn't work anything) of ramping up to do this well, especially with gold. Good luck! Just understand what you're getting yourself into, and set expectations (and budget) accordingly. A piece of fine gold jewelry with a set stone is NOT a reasonable my-first-jewelry-project. Voice of experience, here!
     

    rdc

    Ultimate Member
    Dec 3, 2010
    3,690
    Middlefingurton
    I did some when I worked at a dental lab years ago. We would make the crown or bridge in wax. Encase it in a plaster. Melt out the wax. Then we had a spring loaded centrifuge that held the plaster cast. We'd put the ingots in a little crucible that was attached. Melt the ingots with what I remember being just a oxy/acetaline torch. Once the metal went liquid you'd pour and cut the centrifuge loose. That would force the metal into the entire mold.
    It was fun but not exactly the kind of thing you'd get equipment for just to make one thing.
     

    Melnic

    Ultimate Member
    MDS Supporter
    Dec 27, 2012
    15,282
    HoCo
    Well the Indians in South America did it without expensive equipment but gold was more plentiful and they made bigger stuff. The jewelry I saw down there in the museums were a bit crude.


    Sent from my iPhone using Tapatalk
     

    Blacksmith101

    Grumpy Old Man
    Jun 22, 2012
    22,163
    For investment casting (AKA lost wax casting) jewelry usually the wax model is made and it is invested, burnt out, cast and finished and the finished metal object is used to make the rubber mold for making additional wax patterns.

    The wax pattern should be made as perfectly as possible because every scratch and flaw will show on the casting. After the pattern is made it must have a sprue attached to allow the wax to melt out and the metal to enter. Depending on the design and method you will be using to cast additional wax vents and other features may be needed to get good fill out.

    The next step is to mount the pattern in a flask and fill it with Investment. Investment is not plaster of Paris and their are different types of investment depending on the metals and the size and complexity of what you will be casting. Investment is formulated to allow the air in the cavity to escape through micro pores as the metal enters. It is essential to remove all the air bubbles with wax coating and usually a vacuum pump and bell jar.

    After the investment is allowed to harden and cure the flask is placed in a burnout oven and the wax pattern is melted out and the temperature is then raised to to actually burn out any remaining wax and pre heat the mold for casting.

    The hot mold is then filled with molten metal, which is melted in a crucible, and to insure it fills every part of the mold and has no porosity the metal is usually forced with centrifugal force or sucked in with a vacuum caster. There are other ways such as steam casting or gravity casting but they are more limited in what can be done.

    After casting the investment is broken away the sprues are cut off and the piece is finished in the normal fashion.

    The finished piece can be used as a model to make a vulcanized rubber mold or an RTV mold. The rubber mold will have melted wax, special waxes are used, injected under pressure to make additional wax patterns.

    For setting stones it depends on the type of setting used. from the easiest to the most difficult there are bezel settings, prong settings, bead settings and channel settings and each has its own challenges and you are always at risk of chipping the stone.

    A good place to look at the equipment and materials used would be:

    Otto Frei
    https://www.ottofrei.com/

    Grobet
    http://www.grobetusa.com/casting/
     

    Schipperke

    Ultimate Member
    MDS Supporter
    Feb 19, 2013
    18,540
    Thirty plus years 2-3 hours a day starting at 7:30am. In to today's dollars, I must have swung over $1B of gold.

    Measuring powder water ratio and mixing investment under vacuum and vibration is best. Most important part to avoid porosity is spruing technique, you do not need vacuum to cast gold or numerous other alloys, just a wind up centrifugal casting machine. While not critical for a jewelry, but was in my field was understanding too the expansion rate percent needed in the mold for differing alloys, heat to cure at, so the casting is the exact size of your wax pattern after alloy returns to room temperature. I cast Nickle/Chrome and palladium too, both require much more heat and you have to learn exactly when to swing those by color (through dark glass). Gold is very nice to work with, just use Gas/Air torch, have some flux. Basically when it gets to nice round puddle and shakes like water, its ready to launch. I learned to cast brass when some sharpies made us a deal to cast them phony crowns and partial frameworks, no idea what they were doing with them, but I think gold hit about $1000 at the time. First time I ever saw people carrying wrapped stacks :innocent0

    to insure it fills every part of the mold and has no porosity the metal is usually forced with centrifugal force

    A miscast , where you fail to heat alloy enough to get a complete cast has no bearing on porosity. Porosity is caused during cooling, and why knowing how to sprue, so reservoirs in your sprue get the porosity, not the casting. Where the sprue(s) are attached and creating a resiovoir in them prevent porosity. Knowing how to vent is good, and many do it wrong creating a blind vent back to the button of casting
     

    Occam

    Not Even ONE Indictment
    MDS Supporter
    Feb 24, 2018
    20,239
    Montgomery County
    With all of this good advice having now been aired, maybe the OP can chime in on what his expectations are for quality in the finished results. Sometimes a slightly crusty, cruder, hand-crafted (rather than “fine jewelry” grade) result is part of what’s being sought. For the same reason that some people deliberately go for rustic looking furniture when fine woodworking is available.
     

    Collector98

    Active Member
    Jan 18, 2015
    271
    Hey guys! Thanks for all the awesome advice! Sorry it took me a while to get back. I'm at work and my phone's hard to use at the moment lol. Im definitely not looking for a masterpiece or anything close to it, but just something that looks pretty good. I know it will look like an amateur made it, but that's fine with me. I really liked the one guy's suggestion of using silver, as I looked up the price and it's a lot more affordable to tinker with. I know it's gonna be a steep learning curve, but I've always enjoyed a fun challenge. I'll at least give it a go in silver and see if it's even a feasible option to make it start to finish. I've built a couple ak's and tools, so I'm pretty handy in tool making. Does anyone have suggestions for silicone/rubber for when I make that part? Also, a rough size for the the square/rectangle where the stone will be set would be greatly appreciated!
     

    Mitral

    Active Member
    Sep 6, 2015
    175
    Calvert
    Stone settings are traditionally built rather than carved.
    It I were you I’d invest in some hand tools and silver
    And get the complete metal smith book
    Tim mccreight.
    It’s an old standard.
    To hand built. You need metal files and forming tools
    A torch and solder. A pickle pot and buffer
    Much easier diy A long shaft rotary tool is also very helpful.
    The tool company’s listed earlier are good resources.
    Google is also your friend.
    It’s a craft and an art.
     

    Occam

    Not Even ONE Indictment
    MDS Supporter
    Feb 24, 2018
    20,239
    Montgomery County
    I tend to agree ... fabricating (rather than casting) can produce much better results for someone just getting into it. But just learning to deal with soldering sterling (with the inevitable fire scaling and other fights) is another long slog. But you can trash fifty attempts in silver (and learn a lot along the way) before getting into your first shot at gold.
     

    Mitral

    Active Member
    Sep 6, 2015
    175
    Calvert
    Boric acid / alcohol bath prior to solder
    And a hot pickle pot will keep the fire scale
    Down to a minimum
    Precious metal work is the ultimate recycle exercise
    You can always melt. And reform and start over
    Cutting out solder helps keep purity levels up
    Also be mindful to not over heat at melt and not
    Blow too much oxygen into the metal.
    To keep the porosity down.
     

    Users who are viewing this thread

    Latest posts

    Forum statistics

    Threads
    274,931
    Messages
    7,259,491
    Members
    33,350
    Latest member
    Rotorboater

    Latest threads

    Top Bottom