Two-Part Mold Help; For Leia Ceremonial Jewelry and Medal

Hello!

I hope someone can give me some advice. I've been reading up on mold making, and made a couple simple one-part molds. I need to cast a couple more complicated shapes and I have *no clue* on how to divide these in a mold, I can't seem to find info about that in my research.

I am making Leia's Ceremonial gown from the end of A New Hope. I am going to start by making Worbla versions of her jewelry to start, but I want to take my time making a clay sculpt of her necklace and bracelet, and possibly make the final version out of silver metal clay. However, when casting I am not sure how to divide up the mold; won't it leave a seam I have to deal with wherever the divide is?

I also want to... evil word here... recast a prop I have because I haven't the skill to make the Yavin medal. Not for resale obviously, just because I'd like a resin copy that I won't worry about getting ruined or lost at events, and if I have a Han, Luke and Chewie at an event I'd like multiple medals. However, this one has a slot for the ribbons so, same problem. Does anyone have any advice? I was also planning on using the oomoo silicone rubber from Smooth On as I can get that locally at Dick Blick, unless it's not advised.

Hey verdaera ! I think the difficult part of casting the medal is going to be the hollow, rectangular section that the ribbon goes through. Do you have a photo of the bottom side that shows how the ribbon runs through it that you could share here?

I don't have any experience casting bracelets, but you might get lucky with a simple two-part mold since the bracelet is metal, and it's only a simple crescent shape! I would press it down (or build up the clay around it if the bracelet is soft and might bend!) into clay horizontally (as shown in your photo) so that it was half submerged. Then smooth out and flatten the clay so that it makes contact with the bracelet as near perpendicular as possible. You could even get creative with your sprues and use them as support for the arms of the bracelet as you pull it out of the mold. Your main trunk would run down through the gap in the bracelet's arms all the way down to the inner surface of the bracelet. Your pour cup/opening would be just outside of the bracelet's arms. Your vent branches would come off of the tips of the bracelet's arms and run parallel to the main trunk. Press some small marbles or ball bearings halfway into the clay to use as registration keys in your mold. Smooth the surface around them as you did around the bracelet. If you make your mold walls short enough, say 1/4" above the top of the bracelet and maybe around 1" longer than it on each side, it should be flexible enough to wiggle the bracelet out of the mold without too much trouble from those inner surface undercuts.

Pour your oomoo, let it cure. Pull your mold walls off and clean all of the clay off of the bottom side of the bracelet. Apply mold release spray to the bracelet and top side of the mold. Put your mold walls back in place and pour your oomoo and let it cure. Pull your mold walls off and demold your bracelet and sprue setup.

Wash your mold with clear soap and water. Rinse it thoroughly. Dry it off. Let it air dry completely. Apply mold release spray.

Reassemble your mold and mold walls.

Pour your wax/resin and let it cure. Demold. Desprue. Clean up any flash. Yep, you're going to have to chase some seams. But remember, the better you make your mold, the less cleanup work you'll have to do afterward.

Please note, running your sprue this way will require that you use more wax/resin/metal but your outer surface will have less finish work to chase. If you're concerned about material costs, run a short main pour sprue to the outside center of the bracelet and bring your vent branches from the bracelet's tips up alongside the bracelet and out the top. You will have to remove the main trunk from the outside of the bracelet and chase the surface back to the original shape(s) that were there on your original bracelet.

Good Luck and post up some photos of the underside of the medal if you can!

Ahhh, ok, I see where you're going with this. I'll probably practice with a small object first since I've never made a two-part mold before, but I can picture what you are talking about, thanks

Here's the medal. The indent is quite simply a rectangle which they've filled with hot glue to attach the ribbon.

You could save some effort and do a necklace like I did for about $30.

https://www.therpf.com/showthread.php?t=210211&page=9&p=3949312&viewfull=1#post3949312

Hey verdaera ! Good news is it doesn't look as tricky as I feared. Bad news is that I still don't know how to cast that hollow part. I suppose you could do it as two separate halves and glue them together. The only hang up in doing it as one solid piece will be how to suspend the plug that goes into the hollow. I'll check some of my sculpture books for you later and see if there's any mention of how to accomplish that mold building process.

If there isn't an answer there, hopefully someone with more casting experience will chime in with an answer for you.

Here's a walk through video from Smooth-On to help you visualize the two-part mold process even further...

https://www.youtube.com/watch?v=FQ1A7ZjTsx8

Ok, I've started to seriously get back into this project, and I'll be working on the necklace. My plan is, I am going to sculpt a positive of her necklace piece, and make a silicone mold of the backside of the piece, since I'll be using silver clay (the metal version that you can fire). I'm thinking I can roll out the clay to the thickness I'm looking for, push it into the mold, and touch up the front. Anyone have any suggestions for a good clay to use that will dry/be baked hard?

I decided to use jewelers wax to carve this because it will keep its shape better than clay. This is the first time I've carved something, so I'm pretty happy with this. Now I have to carve out the back. I first plan to cast this in resin with aluminum powder, and eventually I'd like to build a small forge and cast this is aluminum or pewter. I'm just hoping I don't break my positive and mess up making the mold. I will probably keep it a tad thicker than the original since I'm worried the resin will break.

If anyone who knows what they are doing has any advice for me, I'll gladly take it! I have no clue what I'm doing...

Ok, I've just got to finish smoothing the back, but this is my finished piece. I'm going to drill the holes for the jump rings after it's poured.

I understand how a two-part mold goes together, I'm just not sure where I should put my part line with the undercut. It'll be easiest to pack clay around the front of the necklace, but wasn't sure if I can put in the pour vent and sprue when I pour the first side? Can anyone give me some guidance please?

I am not an expert but is that even possible to do mold in one piece in that shape.

It would seem that you have to cast the roll over as solid then individually mill out the undercut.

Or

Create a master that is flat, then roll the top of each piece.

Or

Make the master into two parts an assemble after casting.

Or

3D print.

Like I said, I’m not an expert.

Any progress?

Hey verdaera ! Great start on your wax carving! I think you went too big though, unless of course you have wee small hands. My onscreen guestimeasuring has the individual pieces around 1-3/16" square.

Here's a couple of images for you if you need them...





These are not images of "THE NECKLACE" and "THE BRACLET" she wore. These are images of what are said to be "re-released" jewelry by Lapponia. Originally designed by Finnish designer Björn Weckström.

I used these two images to guestimeasure Carrie's eyes and necklace pieces...





I found these three images of another necklace (Galactic Peaks) made in 1971 by Björn Weckström, which might help explain how he made the Planetoid Valleys Necklace (Princess Leia's)...








You might want to play around with some silver Sculpey. It'll allow you to work quickly and get your basic shapes down before you carve your hard wax.

The latches on these necklaces are something else! Good Luck on those!

I hope this helps you!

Ridire Firean said:

Hey verdaera ! Great start on your wax carving! I think you went too big though, unless of course you have wee small hands. My onscreen guestimeasuring has the individual pieces around 1-3/16" square.

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Actually, I do have wee small hands So small I can rarely find gloves that fit me. I'm accurate Princess Leia sized, actually. By my calculations and from someone's measurements who owned one of the necklaces, I made my pieces about 2.8cm, which is smaller than the 1-3/16th you guestimated, if that gives you an idea of how tiny my hands are

I did try playing with silver sculpey first, but it was too pliable; I'd shape one area, and it would misshappen in another. That's when I switched to carving. I took pictures from every angle and layered them over in the computer so I'm pretty happy with my carving for being a first timer.

Mara Jade's Father said:

Any progress?

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Sort of. I wasn't getting answers here, so I decided to post in the main replica prop board. Need Advice on Making Mold - Leia Necklace

I poured the first half of my mold, but got sick over the weekend so haven't made any more progress. I'm still a little stuck on what type of resin to order. I feel I need something that has some strength to it so the part that gets drilled out for the jump rings won't be prone to breaking.

I posted the size info a while back. You can find my info here:
Leia's Ceremonial Necklace: Prop Replica Collector Options

Mara Jade's Father said:

Just wanted to bump this thread up with some images from an auction for one of the real necklaces a few months back. There were some good shots and some info about the size.

View attachment 530624 View attachment 530625

The individual piece size is 25 x 27 mm and the total length of this necklace is 41 cm.

I know that the company has made this necklace with variations such as number of panels but from what I can tell from images of the real prop, this one matches the panel count.

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Mara Jade's Father said:

I am not an expert but is that even possible to do mold in one piece in that shape.

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Not an easy project for any beginner due to the nature of resins and air entrapment. It could be done if the resin is a slow cure, like epoxy, and you use a syringe to force resin in through "breathers" which would be located on each curved part and in the center of the other end.

cavx said:

Not an easy project for any beginner due to the nature of resins and air entrapment. It could be done if the resin is a slow cure, like epoxy, and you use a syringe to force resin in through "breathers" which would be located on each curved part and in the center of the other end.

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So am I adding a couple sprue's to the curved parts then?

I planned on trying to cast these in white metal, but it never seemed to happen! They could either be polished up or plated in copper, and then real silver.

Hey verdaera ! Assuming you're going to pour the piece vertically, with the two half-round curved parts at the bottom pointing upward, you would simply add a vent to the top of each half-round part. A couple of small 1/8" wax rods would be perfect. Just heat weld them to the top of each hump and bring them straight up and out next to your pour cup.

I'm also assuming you've made your mold to cast more wax pieces all by themselves. And that you'll sprue them individually after pouring. And that you plan to make waste molds for each piece which you'll then burn the wax out of the waste molds and pour your resin/metal in for your final cast pieces. If you're pouring resin into waste molds though, be super careful breaking your pieces out! It's much easier to demold bronze from a waste mold than epoxy resin.

You could make a more elaborate silicone mold that would mold the pour-cup, sprue, and vents all in one and then simply pour your final matieral into that too.

I've been trying to wrap my head around how these pieces are made, and the more I look at the different (casting years) necklaces, the more I believe they were made up of individually hand wrought pieces. I also think that they may have been cast flat, then heated and had their "jump rings" bent into position. There was a gal at the university who was a jewelry major, I'd love to pick her brain on this. Haven't seen her in 22 years though.

I'm thinking you could make a simple two-part mold if you kept it very thin, like 1/8" thick over the piece, and then had support walls to help hold its shape when you do your pours. You might get away with pulling the resin out unharmed with a thin enough mold that you didn't have to worry about the undercuts of the jump rings.

It might be worth your time to experiment with Smooth-On's Starter Pour Kit. You can get them from DickBlick, just check the date on the box, I forget now what Smooth-On said when I asked them about shelf life, but I think it was 3-6 months. Anything older than 6 months for sure stay away from just to be safe.... 34106-1009 - Smooth-On Starter Kits - BLICK art materials

If you need a doodle for sprue ideas, give a holler.

Ridire Firean said:

...and the more I look at the different (casting years) necklaces, the more I believe they were made up of individually hand wrought pieces. I also think that they may have been cast flat, then heated and had their "jump rings" bent into position.

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I agree with you. I know nothing of jewelry making but that always seemed to make sense to me. In fact, I believe that the actual panels were made square (27mm x 27mm) and then when bent over, that is how you ended up wit the 27mmx25mm (actual measurements from similar necklace used in the movie) panel.

My advice strictly as a prop replica collector, is to go back to the sculpting phase and redo his master. The detailing of the piece is great but the actual size/shape IMHO is going to throw off the end look of the replica. You can even see the difference in the picture posted above where he holds the master up against the screen image of the real necklace, you can see the real necklace has a rectangle shape, not square. I'm sure his will look very nice but I fear it just won't look right.

As I posted before, I made an economy $30 version (plastic and paint) using Bogleo design found at Leia's Ceremonial Necklace by Bogleo on Shapeways

I really liked his final design and I would have even paid $400 to get the panels 3D printed in raw silver if he would have made a split panel for the closure.

I think raw silver is the closest replication of the real prop's surface. As you can see on the real necklace, it's not a smooth mirror finished as a lot of people assume. Not knowing a lot about jewelry making, I am not aware of how you go about getting a texture like that.

Not quite! I was going to lay it down more flat so any seam line is around the outside of the piece and I didn't have the rolled part hang up on the mold (again, this is beginner logic, I'm researching as much as I can but I'll learn more by doing.) I was going to put the pour spout towards the back. I'll take a picture tomorrow when I pour the other half of the mold. The wax and the silicone don't really cost too much so I don't mind considering this my first prototype. I can always redo it, especially since version 1.0 will be resin. I will probably recarve (or re-pour in wax and retool it a bit) when I do get ready for metal. I was using wax just because I was having trouble with clay, I don't entirely understand the lost wax technique or why I can't just make a two-part mold the regular way and pour the molten metal in that way. I made my mold .5-.75" thick, was worried about going too thin on such a small mold, but is that too thin?

I agree about the pieces being hand-rolled, I just don't know how to do that so I'm trying to make do

Mara Jade's Father said:

My advice strictly as a prop replica collector, is to go back to the sculpting phase and redo his master. The detailing of the piece is great but the actual size/shape IMHO is going to throw off the end look of the replica. You can even see the difference in the picture posted above where he holds the master up against the screen image of the real necklace, you can see the real necklace has a rectangle shape, not square. I'm sure his will look very nice but I fear it just won't look right.

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Are you talking about my post? You realize I'm female, right? I'm making this replica for my Ceremonial Leia costume.

That reference picture on the screen is a little skewed because the pieces are tilted and laying on a dress form. Here's a more straight on comparison. I do have some shape tweaking to do. I'm still going to make and pour this mold in resin to get the practice and so I have something to wear with my costume to SW Celebration, but I will definitely retool this to get it as close to accurate as I can before attempting metal. I want to get some mold experience first before I dive into forging, I just need to figure out some of these beginner issues and get experience points first

Are you talking about my post? You realize I'm female, right? I'm making this replica for my Ceremonial Leia costume.

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Sorry. You type in a deep voice. Seriously though, sorry about that.

As you can see in your comparison photo, your current shape is square when it should be slightly rectangle. 25x27mm to be percise. However if your just looking for a replica to get you to and through the con, it might not matter to you. You definitely did a lot of work as that detailing is not simple by an means. Not like people are going to be holding up reference image and a ruler as you walk by.

I look forward to seeing how your casting turns out.