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Picture of Lost Wax Casting
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This is a brief outline of my lost wax casting technique. There are several ways to cast, this is just the way I do it as a one woman show!

You can view a lot of my finished work at http://bcyrjewelry.etsy.com

To see more tips, techniques and musings check out my blog - http://bcyrjewelry.blogspot.com

I use all sorts of random tools for my wax working. Most importantly, my fingers, and a tiny needle in the end of a pencil! I also made a little denatured alcohol lamp out of a baby food jar. The wax I use most of the time is a soft brown wax. Its my favorite.
 
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Step 1: Wax work 1

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The beginning of one of my flowers

Step 2: Wax work 2

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Another flower ring, almost finished

Step 3: Wax work 3

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This flower is all sprued! Spruing allows the wax to melt out of the mold and for the metal to get to your piece! not having enough sprues or having them in the proper location can cause your piece to not turn out.

Step 4: Weighing them out

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After all sprues have been attached its now time to weigh them. This if very important and is often forgotten. The weight of the wax is used to determine how much metal you will need for the casting. Because each metal has a unique specific gravity - you will need to know what number to multiply your wax weight by. For sterling, you can do it two ways - you can multiply by 10.4 and then add a half ozt (troy ounce) or you can simply multiply by 15. I usually do both to be on the safe side and figure something in the middle. For very small or very large, using the 10.4 plus half ozt is usually best.

Step 5: Attach to Sprue Base

Picture of Attach to Sprue Base
After the waxes are weighed, its time to attach them to the sprue base or button.
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madmanmoe642 years ago
From what I can tell the investment mould is destroyed each time to get your piece out.
If I wanted to cast multiple copies of an item can I use silicone rubber moulds to cast multiple wax masters?
I've tried pouring carving wax (not decent jewellers wax though) into a mould and it was far too thick.

Yes the investment mold falls apart when you put it under running water or a large vessel of water which can be done about 30 seconds after the poured metal has hardened. If you are making a ring, or something small like this you have it out of the mold and are inspecting it within 5 minutes of heating the metal to molten; the process is quick.

To make multiples in jewelry making what is usually done is a rubber mold is made from a positive metal piece using heat time and pressure. With this rubber mold which has been either sprayed with mold release or coated with a thin layer of baby powder, molten wax is injected then the mold is carefully pulled apart and sequential, nearly identical wax positives are taken out. These wax pieces are cleaned up if required and often put together in a tree like pattern of sprews and mounted onto a rubber canister lid, put inside a steel canister and poured with investment.

If you want to make a repeatable mold of an object from nature like a bug or a leaf, one must first pour a plaster mold with investment, pour a metal positive from this and then make a rubber or silicone mold from that. if you wanted to make a mold of say a walnut, or something from wood or stone you may be able to cast the rubber mold directly from the object.

The rubber mold to make all the wax molds from, is made with a thick metal plate that has a hole in the center in the shape of a soft square and 2 thin plates that serve as end caps. laying the thick piece on top of one of the sheets of metal makes a container within which one builds up rubber sheets that are sticky on 1 side.along one narrow edge one inserts a turned triangular cone and a rod made out of brass, this will serve as your injection port and your sprew for casting. touching this sprew one adds the metal piece of jewelry to be cast with gems removed. small pieces of rubber fill any gaps created and then smooth layers of rubber cover the item so it is uncased within layers of stuck together rubber. there should be just a little too much rubber to ensure solid contact when it begins to melt... ( also note there are different types of rubber, primarily non shrink is more expensive but yields most exact results and there is a more standard rubber sheet which causes a small amount of shrinkage in the final mold.)

Then a top plate makes the rubber mold sandwich and the whole works is places in a heated vice where the vice is turned every few minutes as the rubber melts to make a tighter mold. after about an hour the mold is aloud to cool and all the rubber sheet has melted together.

Using a scalpel, the mold is carefully sliced down the middle revealing the metal positives.

From this the wax may then be injected and as myriad multiples of the small jewelry object can be made in wax to then be poured in investment, burned out, and poured with molten metal.

i don't seem to be able to arrange these attached images in a sequence but here are several images of mold making and pours i did using this process. the very last image is a lizard i found deceased in a pool skimmer so decided to honor its life with a death mask of sorts. the detail picked up by the investment was really amazing. Poor little thing.

The last row shows some grills my roommate made which involves even more back and forth mold making...ending in the lost wax process...so take an impression using either alginate or 2 part polymer clay. Alginate gets more detail but the mold dries quickly, so if using alginate immediately pour a positive using dental stone if using 2 part polymer you have a bit more leeway, some brands shrink more then others. but pour a positive of the teeth by making a little dam back at the molars. with the positive, put a mold release and build up with either dental wax and a flame and wax building tools or press thin sheet wax over the positive and trim with scalpels till desired shape add sprews and pour the investment.

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sarah, how much would you charge to make a silicone wax mould for a ring I want made? pictured is the ring. I could send this very ring to you for the mould "blank".
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bcyrjewelry (author)  madmanmoe642 years ago
Hi there! So sorry for just responding - You can definitely make a silicone mold for making multiple wax copies. I prefer to make each wax individually (to make them all slightly unique) so I like the one time use. There are a lot of different mold types/materials. I don't make many so I'm not a great source of information on that topic... Most people use some sort of wax injector for their molds. I have a friend that uses a syringe and pipes it in to the mold that way. There are different types of wax for using in a mold though - with better flow most likely than just a basic carving wax.
TaranS15 days ago

How did you manage to create such a fragile and intricate piece without it breaking, whenever i try to make a piece such as that it just breaks the wax (I use Green wax).
If its just my poor carving skills can someone link me to a tutorials to carving intricate details?

Thanks

Sure Hacksalot made it!5 months ago

Thanks for providing this Instructable! It was one of the key
documentations I used for my engagement ring, and I really appreciated
being able to reference this document.

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Whats the vacuum machine called by the way?

I've been thinking about doing this for a while now and was hoping to get some gear together.

Great tutorial btw :)

It is actually fairly easy to make your own vacuum chamber and kiln - take a look at the way I did my engagement ring (http://www.instructables.com/id/Casting-Rings-From-Startup-to-Finish/).

rabiddream7 months ago

Out of all the tutorials I have been looking at on the lost wax casting process, yours has been the clearest and most helpful of the process from wax to finish. Thanks much!

E86HotWheels8 months ago

Safety eyewear is important. From the torch pics, it's clear no safety eye wear is being worn. Visorgogs are inexpensive and provide splash and impact protection. They can be found on amazon. Your eyes cannot be replaced. Accidents are called accidents for a reason. If we knew they would happen, then we wouldn't have them.

The tutorial is well done otherwise. Safety is important.

TheStudio72 years ago
Wonderful. I am definitely going to try this. Thank you for sharing.
deth2all2 years ago
I made a lil video of me making a few things , Great instructable by the way, Very detailed .

http://www.instructables.com/id/Lost-Wax-time-lapse-silver-casting/
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Gilligan922 years ago
This is a great guide to lost wax casting and I really enjoyed it. I do have one question though. How do you determine how much metal (in my case white gold) you need by the weight of the wax? What is the equation I need to use? Thank you for the great instructable and your time.
bcyrjewelry (author)  Gilligan922 years ago
Hi there!
Each metal has a conversion factor - the "specific gravity".
I use this chart on the H&S site since there is where I buy my metal.
Standard nickel white gold in 14k is 12.7. Which is different than 18k or palladium white gold.

https://beta.hooverandstrong.com/casting-grain-specifications

There is also a phone app I have that does conversions called iMakeJewelry.

Multiplying the wax weight by the specific gravity will give you the metal needed for the piece. Then you need to add extra for a button. My buttons for gold tend to be a lot smaller than sterling - especially with vacuum casting - generally around 4 - 6dwt depending on the size of the piece.

Hope that helps!! Let me know if you have any other questions!
blindpig5 years ago
Have you considered "steam casting" as an inexpensive alternative to vacuum casting? It is a more primitive method but requires less expensive equipment. Might be considered for experimental lost wax casting trials. Would allow trying the process without buying equipment first. Adding equipment later always an option.
If you have a sec - would appreciate any news / tips re process and gathering tools to do steam casting. send to bridlacy at gmail.com - w my thanks!!
Brian,
Guess I don't know how to get my info to ya......Any suggestions?
Don
Brian tried to send some stuff to your e-mail address and am getting "non-deliverable" messages, is everything OK?
Don
bcyrjewelry (author)  blindpig2 years ago
hm... I'm not sure if it's the one through my website - I get emails to that address all the time and I guess have no way of knowing if someone get bounced back when others make it through?
Ozzynny3 years ago
Hello and thanks for this share. I haven't had much experience with casting, but am. About to try and cast some rings using the soft brown wax that you love so much :) Before this I had used the hard carvingwax a few times. Can you tell me how thin is too thin? The theme we are working with it to "give volume to a ring" so there has been folding, hammerng and milling. I have a few quite thin areas because i wanted to avoid a50gram ring :)

Thanks for any advice you can offer!
bcyrjewelry (author)  Ozzynny3 years ago
Hi there! I'm so sorry for just seeing this - you've probably cast already?

It really depends on the metal that you're using as well as what areas might be thin, so it is a little hard to just give a simple answer. I personally wouldn't go below 18g (1mm) for sterling, although some areas could be thinner. My rings are usually between 1.5 - 2mm. If there are some thicker areas and some thinner areas, you can make sure to sprue appropriately to make sure the metal casts all the way. so if you have a thicker band and some small thinner details on top, that would cast fine as opposed to a thin band and even thinner details.

One more echo of ‘great instructable’ plus – any forums / equipment sites to find used tools to do lost wax? Any replies appreciated at bridlacy at gmail.com.
bcyrjewelry (author)  brianlacy2 years ago
i don't actually... I'm sorry! Maybe try checking the forums on http://www.ganoksin.com/? Someone there may know of used tool forums...
I'm interested in how you vacuum the metal in. Is there a hole in the bottom of you plaster mold and you put that hole over the vacuum peice?
bcyrjewelry (author)  snowluck23453 years ago
Hi there!
No, there is no hole in the mold. Some people use a wax web around the inside of the flask - so when the wax burns out there is a web of holes that allows the vacuum to pull better. i think that may be useful for larger flasks... i use pretty small flasks and the wax webs just weren't worth it for me. The vacuum just creates suction and slight porousness of the investment is enough. I'm always kind of amazed that it works!

If the investment didn't set up properly or there was not enough investment between the negative space of whatever you're casting and the top, the vacuum can pull a chunk off the mold. It is important to leave about 1/8" at the top of the flask, allows for better pull.

hope that helps?
I think it makes sense now. The vacuum pulls the metal into all the pores of the investment, by pulling the air out.
I have not cast anything since grammar school when I made 1 sided lead quarters and passed them to the NUN who was my teacher, (she was highly impressed, cause I recieved neither punishment or wupp'n). I have heard of centrifuge machines , but cacuum?

I are beez confuzzled, you make the mold using wax positive and some kind of plaster (investment?). I understand you suck the air out of the plaster while it is wet, then bake out the "wax" , but how does one get a vacuum to stay that way when you pour in molten silver? or does one do it real fast and then bell jar it and suck air? The mold being so hot the metal does not solidify while you pour, ALLOWING the bell jar to be used with vacuum, after the monolithis pour, (no dribs and drabs)?

sorry if I am too dense for this. I want to cast a few simple shapes out of silver soon and this looks cool. May I also ask does "investment" material have less of a "shrinkage", Or none perhaps when compared to plaster of paris?

I think I need a primer on this !
bcyrjewelry (author)  spark master4 years ago
hey there!
The vacuum for the casting part does not actually use the bell jar. The vacuum has a toggle switch that changes where the vacuum pump pulls from - for investing it is through the bell jar and for casting it is through the table. If you look at the image #15 - right above my hand you can see the hole in the rubber mat and table. The vacuum creates suction through the investment and pulls the metal in to the fine details once the pump is turned on (it is actually turned in before the metal is poured b/c yes, the metal cools extremely quickly)

There is a tiny bit of shrinkage, though not very much.
I will definitely recheck it all out, since I would think th evacuum would suck liquid metal into the vacuum bore and chamber below (the pump). no?

Is the vacuum system good for casting liquid resin and epoxy goops as well? I know all the non understanding on my part is due to total lack of knowlege.But I would like to make a few item and any info I read first will help in the end.

thanks
bcyrjewelry (author)  spark master3 years ago
i totally missed this! I'm not sure about casting other things... I think it would really depend on the mold maybe?
Awesome instructable, but what sort of investment do you use, and if you didn't have a kiln but stuck it in an oven on high, (around 5 hundred or on the self clean thing) for a while would it work to cure the investment, or would it depend on the investment. also could you use paraffin wax
bcyrjewelry (author)  finbar galdeep4 years ago
hey there! I use an investment called 'satin cast' by kerr - it is specifically for jewelry casting and gives amazing detail (down to a finger print!) it also is designed to take the extreme temperatures of the kiln.

I would definitely not use a regular oven for a couple reasons - one is that I usually burn out up to 1300 degrees. For the investment I use, the kiln needs to get much hotter than 500 - sometimes it only goes up to 1150 if I'm casting stones in place.
There might be types of investment that are formulated to cure properly at lower temperatures? I've never looked in to it.

The other thing is that the wax fumes are pretty toxic and I wouldn't want the wax burning out in an oven that was in a house or would be used for food.

You can use any kind of wax and even burn out natural materials and some plastics. (again, that can be pretty toxic too) I have friends who experiment with all kinds of things - some work and some don't.

hope that helps!?
if your using wax not plastics! you can also pre burnout your waxes with steam to remove maybe 95% of the wax! less wax means less toxic fumes.
Chris: cc_tazman11@yahoo.com Owner Mad Scientist's Laboratories & Cavender & Kin Jewelers

OOps! also if you want to reproduce almost anything plastic in metal IE: tin or plastic soldiers, you can sprue them up and gate them for better flow but you will need a high temp burnout!
Bugsley4 years ago
This is fascinating, excellent Instructale. Lots of great details.
Bravo!!
Ichmawida4 years ago
i really want to try this! haha
It seems that those Tables are kinda expensive? Do you really need one like this or can you use an vacuum former used for plastic or a bell jar? also where did you get yours?
thanks :)
mnpazan4 years ago
Very informative! Thanks!

How do you create a seal between the vacuum table/machine and the flask during casting? Looks like maybe a special gasket of some kind, is that right? It looks like there are rings burnt in the surface from previous castings, implying that it might be something that wears out with repeated use and gets replaced. If so, can the gasket be purchased separate from the device?

I have a vacuum setup for resin casting, and it would be super simple to DIY a benchtop unit like that for use with the same pump, if I could figure out or source a seal that could take that kind of heat.
jisaku4 years ago
Is there any way to do this without a kiln?
bcyrjewelry (author)  jisaku4 years ago
i'm not sure about doing lost wax casting w/o a kiln - the investment needs to 'cure' and the wax needs to melt out. there are definitely ways of casting that don't require a kiln. There is cuttlefish casting and sand casting (which i've only done large scale, but i imagine the principle is the same - I have a few friends that do it a lot) With cuttlefish casting, you prepare the cuttlefish and actually pour the metal in to it - it's a one time shot, but no kiln! there may be a tutorial about it on here?
The magazine "Backwoodsman" had an article on cuttle fish bone casting a few years ago. If you google the mag they might have an article index.
ok, thank you
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