Sunday, October 27, 2013

Ironman Costume Part 3: Making the Soft Parts

This is the third installment in my Ironman replica building series so far.  Here's links to the first two:

Part 1: Rapid Prototyping the Helmet
Part 2: the Hard Parts

The whole suit is supposed to look like it's made of metal (I know, a gold-titanium alloy).  So for me nothing detracts from an otherwise well-done Ironman costume like gaps around the joints showing that there's just a spandex-clad nerd inside.  

While I'm not about to go through the trouble of engineering a series of compression articulations for these areas, I still need to fill them in with something that I can convincingly paint to look the part.

This is why I needed to make the rubber bits:
 Fit Testing Neck 2

To see how I made these parts, read on...
In the end, the flexible rubber bits of the suit were made out of slipcast latex.  This is the same material used to make halloween masks and such.  For a really quick primer on how to make your own mask, check out the same tutorial I originally learned it from at

Modifying the maskmaking techniques slightly, I made flexible parts for the knees, elbows, and neck.  Let's start with...

The Knees and Elbows:

The sculpt for the knee and elbow parts was exceedingly simple.  I started with a piece of plastic pipe that was almost big enough to fit the appropriate appendage inside.  Then I chucked it into the lathe and loaded it up with oil-based clay.
Turning Elbows 01

Once I had some thickness built up, I started turning it back down and making everything nice and round using a variety of improvised tools:
Turning Elbows 02

Turning Knees 01

Turning Elbows 03
Once I'd turned all of the grooves, the next step was to sculpt in some of the smaller details.  Here's the finished elbow sculpt:
Turning Elbows 04

The knees were done in much the same way.  Then it was time to set them up for molding.  In this case, I'm going to be making a two-piece stone mold out of Ultracal 30, a gypsum product.  I start by making a clay wall to form a drip tray around the base of the pieces:
 Knee and Elbow Sculpts Prepped for Molding

Then I use water-based clay (which won't bond to the oil-based clay and ruin the sculpt) to make a parting wall:
 Molds with Parting Wall Built

Notice the groove sculpted into the parting wall.  Later this will serve as a registration key to align the two halves of the mold.

Once the parting wall is in place, it's time to start building up layers of Ultracal.  After the first layer sets up, I reinforce the second and subsequent layers by adding strips of Ultracal-soaked burlap:
First Layers Built Up

With the Ultracal built up on the first side, it was time to turn the whole arrangement around and get stared on the other half:
Before Removing Parting Wall

With the parting wall removed you can see the registration groove I was talking about is left behind as a raised ridge in the Ultracal:
Parting Wall Removed

After peeling off the water-based clay, I used a soft bristle brush and some water to clean away any small bits or residue that were left behind.  Then I coated the parting wall with petroleum jelly to prevent it from sticking to the second half.  Then I added some clay blobs to give me a spot to pry against when it comes time to separate the two halves:
Prepared for Second Mold Half

After building up the Ultracal and burlap for the second half, I set the molds outside to cure in the sun:
Second Half of Knee Mold Laid Up

Once the Ultracal had cured, I pried the two halves apart and removed the sculpt:
Elbow Molds Drying

After cleaning out any oil-based clay residue with some rubbing alcohol and a soft brush, I set the knee and elbow molds out in the sun to cure a bit more:
Knee and Elbow Molds Drying

Once they were nice and dry, I clamped them closed again and filled both molds with liquid Mask Making Latex:
Stone Molds Filled with Liquid Latex
I used black for the first pair just to test out the molds.  Mostly because I had a lot of it on hand.

After shaking and tapping the molds to help any bubbles to the surface, the next step is to pour the latex back into the bucket:
Pouring Out Excess Latex
The idea is to leave behind a coat of latex on the inside surface of the mold.  So I prop the mold up over the bucket to drain off any excess:
Draining the Mold

Then I set the mold back upright and let it dry overnight.  Here's the mold with the first coat dried:
First Latex Layer Dried

I did the first set of rubber parts with two coats.  This makes a soft, thin skin.  More coats will make a stronger piece.  When the second coat had dried, I dusted the inside of the latex piece with talcum powder to prevent it from sticking to itself and then it's time to open up the mold:
Elbow Sleeve Mold Opened

So here's the first pair of elbows:
Elbow Sleeves Removed From Mold

After some quick work with a pair of scissors, they were ready to try on:
Elbow Sleeves

Elbow Sleeve Test Fit

Now these parts can be painted, but if the paint wears off I don't want black scratches showing through.  Instead, I tinted another bucket of latex to get the right base color:
Burgundy Color Latex Mixed

Getting the color right ends up being a lot of guesswork.  This is because the latex darkens significantly when it dries.  Based on the bits that dried on my fingers, I think I did pretty good:
Burgundy Colored Latex Dried

The Neck:

I started by printing out the models I had for the neck parts:
Neck Sculpt Start

Since this didn't quite cover all of the same territory as the screen-used neck piece, I printed out a picture from one of the prop auctions that were held after the film finished shooting and used it as a reference to roughly match the parts of the neckpiece that were hidden by the chest and back armor.

Here I am working on the sculpt:
Sculpting the Collar

When I was satisfied that it looked the part, I gave it my standard gloss coat:
Neck Sculpt Shiny

Neck Prototype Finished

Since most of it would be tucked in out of sight, I didn't really get too bent out of shape about the inaccuracies and asymmetries.  I was too eager to get the pieces out of the molds.

Here's the beginning of the mold which I started by laying up some thickened silicone:
Neck Molding Begins

The rest of the mold was a few more layers of silicone followed by a fiberglass mothermold.  Using that mold, I rotocast some tinted urethane rubber and made the first draft:
rubber neck

When I tried it on, I absolutely loved it:
Fit Testing Neck 2

The urethane rubber it was cast in was originally designed to be used as a mold for concrete casting.  Unfortunately, when you add pigments to it, it degrades the strength significantly.  I wasn't worried about it, but after a couple of weeks of sitting on the headless mannequin, it started to crack and split:
IM Torn Neckpiece

So it was time to go back to the drawing board.  It didn't take long to decide that I would just go ahead and make the neck pieces slipcast latex as well.  The only problem is that latex won't work in the silicone mold I made.  I needed to make a gypsum mold.

To that end, I started by melting a few pounds of Chavant NSP oil-based clay:
Melting Plastilene

When it was nice and liquid, I poured it into the silicone mold:
First Coat in Neck Mold

Since the urethane rubber casting had quite a bit of extra room inside, I decided to cast the clay copy thick at the back of the neck so I could carve it down and make it fit tighter:
Thickness built up in Neck Mold

I could've just filled the mold all the way up with clay, but to save weight I ended up filling it mostly with 2-part expanding foam:
Expanding Foam Expanded

Once the foam had cured, I used a hand saw to shave the bottom flat so it would sit upright:
Form Sitting Upright

Then I peeled off the silicone jacket:
Removing Jacket Mold

The clay casting was not too shabby:
Before Resculpting Front

Once I had the clay copy, I went ahead and shaved off some of the back of the neck and added a bit more shape to the top edge in order to hide the wearer's chin in the helmet.  Here's a shot of a foam casting from the original mold next to the clay cast after resculpting:
Old vs. New

Since I didn't want to have to deal with cleaning up seams on the neck, I opted for a one-piece stone mold made of the same burlap-reinforced Ultracal-30:
Stone Mold for Neckpiece

Making a seamless mold meant breaking apart the original sculpt in order to get it out.  I started by picking foam:
Removing Foam from Neck Mold

Then removing clay:
Removing Clay from Neck Mold

The last thing I did was scrub out the inside of the mold with a stiff bristle brush and some rubbing alcohol to eliminate any residual bits of clay:
Neck Mold with Clay Removed

Once the mold was clean, it was time to pour in the first layer of latex:
Latex Poured

Here it is draining back into the bucket:
Draining Excess Latex

And after a few hours drying time:
Latex Drying

Here's me trying on the first copy:
Test Fitting Neck


Now that I had working molds for the rubber parts, it's time to move on to...


The first step in painting latex parts is getting them all scrubbed clean and dry:
Rubber Painting Progress 04

While those were drying, I cleared off more of my workbench than I've seen in years:
Rubber Painting Progress 05

Then I used some clear liquid latex and a bit of red pigment to give them all a base color using the fattest needle I could get for my airbrush:
Rubber Painting Progress 06

Here's one of the neck pieces with the base color:
Rubber Painting Progress 02

The biggest problem with latex paints is that they tend to clog up the airbrush like nobody's business.  I spent all day spraying for a few minutes, cleaning the airbrush, and repeating ad nauseum.  I got very intimate with the airbrush innards:
Rubber Painting Progress 01

But at the end of the day at least I had rubber parts that were all completely the wrong color:
Rubber Painting Progress 03

The next day I set about weathering the pieces so they'd stop looking like red rubber parts and start looking like the rest of the suit.  Here I'm applying a blackwash to bring out the details:
Applying Shading

Here's a "during" shot so you can see the transition:
 Shading in Progress

And a "before and after" showing an unweathered neckpiece next to the weathered one:
Neck Before and After
Much improved.

While the weathered parts looked pretty good, it was going to require a clearcoat to really bring out the look.  I narrowed the options down to two different products.  The first was "Flex Gloss" from  The second was "Snakeskyn" from Douglass and Sturgess:
Glosscoat Comparison

I picked out a couple of the elbow pieces, sprayed them silver (for no real reason) and coated one with Flex Gloss and the other with Snakeskyn.  The next day I came to the shop, found they'd dried enough to wear, and put them on while I went about my work.  After several hours they were both still shiny and whole, so I decided to go with the Snakeskyn for no reason other than I had more of it on hand.

Here's the neck piece with the clearcoat:
Neck 1 Clearcoated

And here's a smattering of knee and elbow parts:
Neck 3 Clearcoated

Here's the workbench after a couple of days worth of rubber painting:
IM Parts Clearcoated

Stay tuned.  I'm still well on my way to making an exceedingly accurate replica of the costume used on-screen:
Screen Accurate 1 

But seriously, there's awesome brewing:

Stay tuned...


  1. This is meticulously awesome! Can't wait to see the finished costume.

  2. I am so, so impressed with the quality of your work. This is going to look incredibly accurate.

  3. are you selling any yet?

  4. Shawn... that neck piece is amazing!! I want it!! lol it would sure beat the one that came with my masked rider suit :P

  5. Is the drained latex wasted? If so, does it at least have some recyclable use? Thanks!

    1. The drained latex goes back in the bucket. Then the bucket gets sealed up airtight so it doesn't dry out.

      Since latex is an air-dry product, it won't cure in the bucket.