Large Scale Central

In-ko-pah Railroad - Molding a figure

Modeling Figures
#1

Here’s another little project I’ve got going. I’ve sculpted a figure of Cris’ grandmother, who is 104 years old. This figure will be seated in the back of my rail bus, so I eliminated the lower legs in order to clear the electronics located under the rear seats.

Anyway, I decided to try making a mold of this figure, so I can cast resin copies. This will allow me to replace the figure if it ever becomes damaged or faded. I’ll also be able to make duplicates to put inside buildings or passenger cars. If this works out, I will do it with all my future figures. (I can’t do it with existing figures because they’re painted, which fills in some of the finer details.)

Here’s one of the photos I used as reference when sculpting the figure. Unfortunately i didn’t get any photos of the sculpting process:

I mounted the completed figure to a piece of 6mm Sintra PVC foam board. It is secured by a screw from underneath. Then I started adding some plasticine clay to divide the mold. It is important to use only sulfur-free clay, to prevent contaminating the silicone molding compound:

At this point I built up a box around the figure, using more of the 6mm Sintra. No glue was used – it’s all held together with #2 x 3/8" stainless steel, pan head, sheet metal screws. This way the box can be assembled and disassembled as needed:

Then I started packing in clay to fill the area which will become the second half of the mold:

I smoothed it as best as I could, then used the end of a paint brush to press small dimples into the clay. This will help to keep the two halves of the mold aligned during casting. After I shot this photo, I decided to add a strip of styrene from the arm’s elbow, down to the base of the form. This will help prevent air getting trapped in the arm, and allow the resin to get all the way into the arm and hand – I hope!

In hindsight, it might have been better to cut the arm off, and mold it as a separate piece. But for now we’ll see how this turns out.

After spraying it with mold release, I filled the upper half of the form with silicone molding compound. I use Oomoo 300, because it’s easy to use and relatively forgiving. It mixes 50/50 by volume, so you don’t need a precise scale or anything like that.

The next day, I opened two sides of the form and starting prying out the clay. I used a small screwdriver to gently dig at the clay. The clay doesn’t stick, so it pulls away from the figure pretty well:

I replaced one of the sides on the form, and removed another for better access. Then I removed the rest of the clay. There was a tiny gap under part of the figure, so I smeared a little clay into the gap to keep the silicone out from under it:

That’s as far as I’ve gotten. More later!

#2

Wow, the url’s for your pictures are messed up… I cannot decode what happened, but there is a lot of extra junk in the url itself.

Take a look at how you are copying the url for the pictures.

Greg

#3

Grr… I don’t know what’s going on, but this site does that to me sometimes. The urls for the images were exactly the same as on my other posts, but for some reason they weren’t working. I had to manually copy each url and use the “insert image” button. And then when I do that, the image doesn’t appear in the post, until I click “preview” or “post”.

#4

Pix work now, Ray. But you left off the most important part. How did you make the original figure? Is that “merell” (I put it in quotes for a reason) scupting freehand?

What scale is it? 1:20.3 I presume? I’d like one or two of those in 1:32!

#5

Sorry, I neglected to shoot pics of the sculpting process. I’ll try to do that next time. I use Sculpey “Primo” over an armature made of twisted aluminum foil. It’s 1/24th scale.

I had a four part series on sculpting figures in Garden Railways, beginning with the December 2009 issue.

#6

Onward to part two…

I prepped the surface of the silicone by brushing on a thin coat of petroleum jelly, thinned slightly with a bit of mineral spirits. When doing this, you must be careful to cover every bit of of the silicone surface, otherwise you won’t be able to cleanly separate the two halves of the mold.

I did not brush any petroleum jelly onto the figure. For one thing, I didn’t want it to obscure any of the fine details. Also, I didn’t know whether or not the p.j. would affect the poly clay.

Then I replaced the side of the form and poured the silicone molding compound into the open end. I let it cure overnight:

The next day I disassembled the form, and pulled apart the two halves of the silicone mold:

I coated the mold inside and out with a mold release spray that I bought at Michael’s, and let it dry:

The mold was held together with a rubber band and two pieces of foam core art board. Then I mixed the resin (Smooth-Cast 300) and poured it in. I placed a small scrap of wax paper over the opening and held it in down with a flat weight:

This resin sets up after just a few minutes. I opened the mold, revealing the first casting. Looks good so far…

The good news is that there is minimal flash, and the arm and hand turned out well. However, the first casting revealed a couple problem areas. Air trapped in the face area caused large gaps in the nose and chin. Now that I know this, I can correct for it on the next casting:

When I made the second casting, I didn’t put the two halves together right away. Instead, I mixed the resin first. Then I dabbed a couple drops into the face area. Only then did I put the halves of the mold together, and pour in the rest of the resin. This made a big difference.

The second casting has only a couple very small surface bubbles, which can easily be filled with modeling putty:

All in all, I think this was very successful, and I learned a lot so that I can do even better the next time I mold a figure or other complex shape.

Next post, I’ll paint this figure.

PS:

The material for the silicone mold is called OoMoo 30. I like this stuff because you mix it in equal parts by volume, not by weight, so you don’t need a fancy scale. It’s also pretty forgiving of minor inaccuracies, so you don’t have to worry about being super precise. It’s made by Smooth-On, but I get it from this art supplier: http://www.dickblick.com/products/smooth-on-oomoo-30-silicone/#items

The urethane resin I use is also made by Smooth-on, and is just as easy to use as the silicone rubber. It’s called Smooth-Cast 300: http://www.dickblick.com/products/smooth-on-smooth-cast-300/

#7

(https://encrypted-tbn1.gstatic.com/images?q=tbn:ANd9GcQBohKvObUqCENuqyTI-YjUTSNPbcoIG7VdjcRuPWjcxlsPwr7mDMvZqg)

#8

(https://encrypted-tbn1.gstatic.com/images?q=tbn:ANd9GcQBohKvObUqCENuqyTI-YjUTSNPbcoIG7VdjcRuPWjcxlsPwr7mDMvZqg)

Bravo Zulu!

#9

Wow Ray. Great job.
I can’t imagine making a figure from scratch.
I tried casting O gauge pilots and steps with a different brand. I got surface defects that I had to work around. I learned to add sprues to give a place for the air to go.
My biggest problem was the molds being ruined. Seemed that they had air trapped against the master part. If they didn’t show up at first, after a few casts they popped up and became worse. Looked just like your casting problem but mine was caused by tiny defects in the molds.
I worked out casting flaws with sprues and different resins and pouring methods. I gave up on the silicone mold making because I couldn’t get it perfected. Maybe I’ll try again someday with a different mold making product.

#10

Part three…

Before i get into painting, I’ll show how I made the glasses. I started by putting together a form. This was made from two .080" styrene rods, with a .040" x .080" strip as a spacer between them. I wanted to see how fine a wire I could use for the glasses frame, so I found a grain-of-rice bulb that had very thin stranded leads. I separated the strands and used one for the glasses, wrapping it around the form to get the basic shape:

After removing it from the form, I used tweezers and a needle-nosed pliers to adjust the shape as best as possible. Then I stuck one end in a small blob of clay to hold it in place while I added the “lenses”. These were created by dabbing a tiny smear of gloss, acrylic medium to each opening in the frame:

The wire is almost as thin as a human hair, so handling and manipulating the glasses is a real challenge! Here’s the finished piece next to a penny:

Now, on to the paint… I started by spraying the casting with a coat of white primer. Then I used craft acrylics to paint the hands and face, beginning with a basic “flesh” tone:

Next I added some very subtle shading to the face. I mixed a tiny bit of red into the flesh tone, and applied it to the cheeks and other areas. A slightly yellower flesh tone was used on the sides of the cheeks and on the forehead. Then a faint bluish tinge was used to create some shadows where needed. All of this is extremely subtle and probably not noticeable except in an extreme closeup. Anyway, then I painted the teeth, the lips, and the eyes:

I painted dark maroon base coat for the shirt, and painted the pants vanilla white. The hair was painted a slightly gray off-white color:

I dry-brushed a faded red-brown onto the shirt. Then I gave the whole figure a very thin wash of dirty black (black with a touch of brown). I used the tip of a brush to sop up excess paint from the wash. When this dried, I dry-brushed some white on the hair to add highlights. Finally, the figure was given a couple coats of Kyrlon UV-resistant clear matte.

I drilled two tiny holes to insert the ends of the glasses, placed them in position, and then secured them with a bit of matte medium, then touched up the paint. The glasses are so delicate that installing them on the figure was even more tricky than making them. Here’s the finished figure:

At last, the figure was mounted in the railbus and secure with tacky poster putty:

As far as the sculpting goes, this wasn’t my best work. I should have spent a little more time on the face to get a better likeness. But it’s close enough.

#11

Great tutorial post. I’ve made a bunch of figures, but they were singles. I have done a lot of casting for other things, but never for figures. She looks good sitting in the Rail Bus. It completes the scene.

#12

That’s purty nifty…:wink:

#13

(http://www.raydunakin.com/Site/IRR_Figures_files/Media/IMG_8910/IMG_8910.jpg)
On the rails to Rays house for Turkey??
Out standing as usual!

#14

Thanks, everyone!