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Sculpting Rahm Kota Armor

Koda Vonnor

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Hi all.


I wanted to keep a running progress of the Rahm Kota armor here, as it pertains to sculpting, mold-making, and fiberglass casting, if not to Imperial costuming. This board has been helpful to me in getting this project under way, and I hope to gain critique and suggestions as I move forward. I am starting with zero experience in these areas, and am mostly figuring it out as I go. What comes out at the finish will most likely be redone for accuracy after the Force Unleashed media event's release. I also hope it will be helpful to others whose desire and determination outweigh their artistic experience.


After two attempts, I managed to get good working armatures for the chestplate and shoulder bell.






I plan on first making a thin spread of clay to form the basic backing plate and overall shape and border of the chestplate. The dotted lines are just guides. I wanted to see how the lines looked from full-front, 3qtr, and profile. I will adjust the overall contours based on those views, but I expect the side edges of the backing plate sculpt to rise off the armature about 1.5" higher than at the center of the belly or the high-point of the breasts, which will be flush at those points. His armor is pretty flat from just above the breast-line to the bottom edge, but fades at the sides/top from a slight break point. I want to leave enough room for 6-8 thicknesses of fabric (undertunic, outer-tunic overlapped, harness, tabards/capes) under the BP without it protruding off my body.


I'll post more pix after I get the shaping spread on.





The pencil line is vertical when standing normally, and centered front-to-back. The biggest challenge as a non-sculptor will be symmetry, as I plan to cast both bells from the same hard master.


I dread it. Any suggestions?





Those are early attempts at slabbing, surface smoothing, and edge cutting, and have since been recalled to the clay-pile. Any advice in those three areas is greatly appreciated. :?


More progress pix to follow as I go.


Many thanks,


~ Koda

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Thanks for sharing your project with us; this is going to be pretty cool.


For symmetry... that's a challenge. For the most part, you'll have to eyeball the pieces, but I've found that a pair of calipers works well to help keep things symmetrical, also. If you have a midpoint, you can measure the width of each side from that point with the calipers, making sure that everything lines up.





If you're using water based clay, it's a good idea to paint your plaster base with a good coating of spray paint to seal it. Otherwise, the water will soak in and your plaster will begin to collapse. If you're using an oil based clay (my personal preference), you shouldn't have that problem.


Pam :-)

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It's Klean Clay. Didn't want to spend a lot on clay. I was messing with it over the weekend and found that my work lamp (100w) made it real easy to smooth the surface with just my thumbs, working the clay in mini "sand-drift" looking waves from the higher spots to the low spots. As long as I kept my work close to the lamp it was easy to push the clay around. It'll be a slow process but seeing progress, however small, helps. :D


Thanks for the tip and link for the calipers, I will give them a try.


I am seeing that as long as the surface is close to smooth, it can be sanded to smooth after the piece is cast. How thick should/can the gelcoat be to allow for finish smoothing? That is, how close to "true" does the clay surface need to be before taking a mold?


Many thanks!


~ Koda

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I did the rough extents of the shoulder bell today. I cut templates out of poster board so I could get the curved edges and cross-sections just right. Tomorrow I will fill in all the clay and smooth it out. I've finished the left handguard model too, and it's ready to cast. You can kind of see it in the background. :D











~ Koda

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I am seeing that as long as the surface is close to smooth, it can be sanded to smooth after the piece is cast. How thick should/can the gelcoat be to allow for finish smoothing? That is, how close to "true" does the clay surface need to be before taking a mold?



The clay surface should be as close to the final look as you can manage before you move on to the molding process. It's a LOT easier to touch up imperfections in clay than it is to touch up a solid material when you have deep indentations like that.


The best way to go about the process is to make the clay sculpture, and then make a mold from it in soft plaster. Clean the mold, seal it, spray in some mold release, and then fill the plaster mold with a very thick layer of thickened fiberglass which is then backed with fiberglass mat or cloth for strength. (WEAR A RESPIRATOR!) I thicken fiberglass resin with a heavy dose of talcum powder so that it will firm up and stay on the walls of the mold better. (The powder is a safe additive. Bondo is really just fiberglass resin with a VERY large amount of talc added.) Even after being thickened with powder, the resin will still tend to pool at the bottom of your mold, so you have to keep brushing it up the sides until it sets up.


Once the resin is set, you can remove the plaster mold. It usually breaks, but that's okay because it was just temporary. You now have a fiberglass master sculpt which can be sanded, have any low points filled with bondo, or whatever else you need to do with it. Once that piece is looking as good as you can make it, it's time to make a high quality mold from it, and make your costume castings. I recommend using a flexible platinum cure silicone such as Dragon Skin for the mold. Snce you have deep cuts and you'll need to make multiple copies, you'll want a very durable mold!


Hope that helps!


(Great idea using the template... that looks like it's helping you a lot.)


Pam :-)

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Thanks Pam for the advice.


There won't be any deep cuts on the shoulder pieces, they will be a smoothly curved surface throughout. The photos above only show the extents (perimeter) shaping sculpt. I have since filled in the rest of the model and am smoothing the curves now. The breastplate will have a narrow tapered cut running vertically up the centerline, but only about 3/8" deep.


I like your idea of making the mold in silicone since both the shoulders and the breastplate will have moderate undercuts at the edges. I viewed a Smooth-On video where they did a silicone mold and backed it up with plaster. Have you any experience doing that type of thing? Might you recommend it for these pieces? Is a plaster backing even necessary?


I was trying to limit additional expenses as much as possible. Would a two-piece plaster mold work for the shoulders? Does keeping the model cold help to prevent surface distortion while applying centerline mold walls?


I'm getting close to the point where I'm not sure how to proceed.


Thank you for your help.


~ Bill C.

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Here are some more shoulder armor progress pix:


I have smoothed down the surface and added mold walls around the edges. Those will define the 1/2" thickness of the finished pieces. I still have to seal the model with clear spraypaint then put it in the fridge for a bit. Then I'll add a center ridge wall to make a two part plaster mold. I want the model cold to limit squishy distortion when I put on the center ridge.


Also, I realized after looking at these photos that my outside mold walls need to taper in the opposite direction than what they are now. I've always been a little 3-dimensionally challenged. :? I will cut some clay wedges and add them to those walls.








~ Koda

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Today I went back to the handguards. I wanted to practice with the plaster before tackling the two-piece mold for the shoulder bell.


I cut out the right side and shaped and smoothed both. Then I hot-glued cardboard walls around the clay and covered both assemblies in clear gloss spray paint. I mixed up some plaster and poured it into the little cardboard "bowls."


Out came the handguard molds! :D


Now to just spread in some liquid plastic and fiberglass.


There will be many "firsts" for me in this project, and I wanted to share lessons learned.


- When mixing up the plaster, start with half the water you think you'll need (The level rises as you add plaster and I ended up having to sluice off some half way through mixing)

- Add less plaster than you think you'll need. I kept adding plaster as I mixed 'cause it felt too thin to me, but when I went to pour it it stuck in the bucket like a Wendy's frosty. Luckily I was able to coax it into the mold assemblies and tamp it down (mostly) flat.

- Resist the temptation to use your thumb to smooth out the hot-glue. :shock:





~ Koda

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After much reading and contemplation, I've decided to make a junk mold of the shoulder (and BP) first. I need to get a hard model and shape that before I take final molds. I have much more experience in working hard plastic than working clay (the frustration level is insane :x ) :?


I have lots of bondo and resin to build up the larger pieces once I get a hard shell to work with. I also got some "FeatherLite" resin from Smooth-On that I want to use for the shoulders. The stuff dries solid but lighter than water! I plan on attaching the bells right to the tunic so the lighter the better. To do that I need an enclosed block mold to pour the plastic into. Easier to make one of those with a finished model (front and back surfaces) than to try to press barrier walls onto clay without distorting the surface.


The breastplate will have a non-cosmetic back, but will still need a two-piece mold due to the edge undercuts (need to keep a working mold for posterity 8)).


With the limited crafting time I have this will put the project completion date farther out, but I can't bring myself to do it half-way. :P


I'll continue to post updates. Thank you for the space.


~ Bill C.

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Another weekend, another project update. :D


Took casts of the handguards yesterday, I mixed up gray colored gelcoat (3wht/1blk) and laid it onto the molds, then practiced layering in fiberglass. Put in 4 layers and finished them off with another layer of gelcoat. The surface got a lot of brushmarks in it. I think I used too much sealer or mold release or something. I'm sure I can sand down the brushmarks.


Today I cast the hard model of the shoulder piece. I made my own gelcoat for this one (1bondo/1resin) and did not use a brush to spread it into the mold. I just poured it in the "bowl" and kept rotating it all around 'til the gel started to set up. This left only a VERY thin coating around the edge undercuts, so I mixed another batch and made it thicker (2bondo/1resin). This coat I brushed in and after it started to thicken I pushed more into the undercuts. I layered in the fiberglass (3-4 layers) and finished off the undercuts with a VERY thick paste (4bondo/1resin). I want to let it harden overnight before I crack it out of the mold.


I'm going to build up the inside with clay and sand the outside smooth, then make a two-piece mold from that. I'm going to make the final shoulders out of poured feather-weight plastic.


You can see the fiberglass layers in the photos.





~ Vonnor

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Here's the hard model for the shoulder bell...







I still have to shape the curvature better and smooth out the surface some more, but it turned out decent and workable. I will fill in the back side with clay to about half inch thick overall, then make a two part mold to cast the final pieces.


Lessons learned:

- You can see in the pix there are a couple dozen low spots, 5-6 of which were from pockets of un-cured resin. I know what I did wrong there, I mixed the bondo hardener and the resin catalyst in the same cup that I mixed the bondo and resin in for the gelcoat, then poured the whole mess into the mold. I should have poured the homemade gelcoat into another cup before adding the hardener. There was some unmixed resin on the sides of the cup that got into the mold as I poured. :?


- I should have left the plastic harden overnight before breaking it out of the mold. When I did the handguards they shrunk a tiny bit as they cured, and popped right out of the mold with no problems. I only waited like three hours. When I demolded it there was a boatload of plaster totally stuck to the model. Also, just from jockying it around to try and break it free, I put several cracks in the bondo edges. Luckily, the plaster was pretty easy to scrape off and the cracks I can fill with epoxy.


I'm sorely tempted to leave the low spots in the model. With a little creative weathering they could be blaster dings. :P


More to come...


~ Koda

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I've back filled the shoulder bell with clay, and today I smoothed it all out and masked it off for taking the mold.


I cut two cardboard templates from outline tracings, and hot glued them to the model from the back. I put double-sided tape along the edges first to make it easier to remove the boards. The front join edges I filled with clay.


I put in the pour-hole and registry keys, then sprayed the whole mess with clear coat.


Tomorrow I make the mold.






~ Vonnor

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Could only finish half the master mold.


I ran out of plaster. :shock:


I used Rebound-25 from Smooth-On for the rubber core. It was pretty easy to work with. Got more art plaster on the way. Will do the other half when it arrives.


By rights it should have air-holes to either side of the pour hole. I forgot to put them in. I'll cut some in on the second half.






~ Koda

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Well, it wasn't the weather that prevented me from casting the shoulder armor yesterday. It was rotten luck (maybe rotten engineering more like).


I strapped the two halves together as tightly as possible and went to fill it with water, so I could tell how much resin I'll need. The water leaked out all over the place. :shock: So I tried vasoline around the rubber seal, still leaked badly. Then I tried painting another thin layer of pink stuff on the plaster around the rim under the rubber edge, to kind of build it up so the rubber would press more tightly together at the seal. Strapped it up again and tried the water.


Still leaked, but not as bad. :cry: Plus I have qualms about building up the area between the plaster seal rim and the rubber seal rim. It seemed to cause the rubber to not sit tightly against the plaster. This may distort the cast. :?


I made a run to the hardware store and got some caulk, latex with silicone in it. Ran a bead of caulk around the edge where the rubber meets the rubber. Sprayed some mold-release on one half and strapped the bad boy together again. Waited overnight and went for the water a third time. Didn't appear to leak but when the water got up to the pour-hole it WAS going down slowly so it must be still leaking. Quick emptied it into a pan (measured 31oz) and took it apart. The latex caulk had not cured. :roll:


I'm pulling my hair out over this! :x


Maybe I got some burrs on the plaster rim keeping the two halves from sealing. I don't know, I guess I'll try shaving a little off the plaster so the rubber seals tighter. Any ideas?


~ Koda "ReallyStartingToHateThisProject" Vonnor

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I finally figured out how to fix the leaky shell mold.




Ran a bead of that gunk all 'round the rim where the two rubber halves meet. Waited overnight and filled the mold with water. Not a leak in sight. :mrgreen:


Only one small problem, when I took the shell apart to dry it out and prep it for the plastic pour, the blue gasket stuck partly to one side of the rubber and partly to the other side. In trying to get it apart cleanly I tore the gasket. I was able to pick off the residue and clean up the lining, then I applied mold release and another gasket bead. I will do the first pour tomorrow. Hopefully I put on enough release to keep the gasket from sticking. We'll see.


I do expect to have about a 64th thick flashing along the edge to remove, due to the gasket.


Pix to follow after the resin cures.


~ Vonnor

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I cast the production shoulder bells today. They came out all shiny and spiffy right out of the mold. :D


These pix are from the 2nd bell cast. I forgot to paint vasoline around the air holes on this one and demolding it took a couple of plaster divots. I think it should still be usable though as the hard shell backing the rubber seal is still sound. Note the blue RTV silicone gasket bead around the rim. This worked like a champ and only required a couple of elastic straps to hold the shell together.


I used a teaspoon of gray color tint (3 white / 1 blk) in exactly 30oz of resin per bell. This is FeatherLight? resin from Smooth-On. It can best be described as liquid sintra. I really like the results. It is heavily filled with some kind of plastic powder and the finished pieces are lighter than water. It pours with the viscosity of maple syrup and is easy to control. Each bell weighs just under a pound and is 5/8" thick in the center tapering to 1/2".


Tomorrow I beat these up and make them look like the handguards. :mrgreen:








~ Vonnor

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What you see here is one thin coat of dark gray with a couple spot-spritzes of copper and black, all on top of a boatload of silver. I had to rush this morning to get these painted before the rain storms arrived, so I wound up making each coat of silver WAY too thick. :shock:


Consequently, I'll have to give them a lot of time to dry before I scratch 'em up with the sandpaper.


...more pix later ... (yeah, what a surprise) :P





~ Koda

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Thank you for sharing your progress on this project. The solution you've adopted for your gauntlet closure--shown in a separate thread--is both very effective and handsome. It is inspiring really.


I very much like the research, craftsmanship, and tyme that you are applying to this character. It is good work.


One thought I would add is to favour the 3-D model over the Hasbro action figure for the details of the armour and dress. Also, ?have you given thought to how you will recreate this Jedi's grey top knot and goatee?


Kudos to you,


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