Casting Resin Heads
Casting resin heads
This article is all about making and casting resin replacement heads for 1/6 scale figures.
This text isn't a true "step by step" in that we won't lead you though to your final result as we have before. It's simply a re-post and expansion of a casting tutorial that we had posted to the alt.toys.gi-joe newsgroup a few years back and that we had received several requests for copies of.
If anything isn't clear or if you have questions about anything not covered, please feel free to email Kris and I and we'll try our best to answer your questions.
- Materials selection
- Mold making
- Experimenting with casting
- Sculpting and master preparation
#1: Materials selection
The first step in planning your first resin head....you'll need to find the materials.
You'll need a jar of liqid latex for making the actual molds....that's available from your local model/craft shop. Next item is the resin for pouring the heads. The only other items you'll really need are assorted odds and ends such as toothpicks, popsicle sticks, disposable mixing cups, and sheets of cardboard.
You can buy clear polyester resin at the craft shop....it's usually sold there as an "imbedding" resin in that it's meant for imbedding craft items in a clear block of resin for display. Think in terms of the old "fly in the icecube" gag and you get the idea. Usually sold under the brand name "Aristocrat", "Clearcast", or "Crystalcast".
The upside to imbedding resins is that they will almost always harden to a glass-clear finish and be hard as rock. They can be used to make some totally unique effects such as "color swirl" (like a glass marble) and they can be tinted/colored to whatever shade you want. The downside to them is that they are expensive as hell if purchased from a specialty shop like a craft store. They stink to high heaven while you're working with them and require good room ventilation. They can also cause problems such as "scum glazing" at the end that require extra steps to remedy.
The next type of resins are the new generation of polyurethanes. Resins such as Alumilite fall into this category.
The upside to polyurethane resins is that they have fixed and standard working properties....they don't smell nearly as bad as polyesters....they come in different colors and different working characteristics.
The downside to polyurethane resins is that they have fixed and standard working properties (they can't be experimented with)....they come in different colors (no real custom coloring is possible)....and they cost an arm and a leg when bought as "specialty resins" which you are buying them as.
And here we come to the first tip....
The polyester "imbedding" resins you would pay $10 per pint for in your local craft store are the exact same thing that you can pay $10 per gallon for in your local home supply store. Even the cheap ones such as good old Bondo fiberglass resin are nothing more than standard polyester resin with a slight color tint to it.
The Alumilite polyurethane resin you're paying $10 per pint for in your local model/craft shop is the exact same thing your local home supply store sells as sidewalk sealer and roof coating for a fraction of the cost.
Just remember that when you buy a "specialty" resin for hobby and craft work that the resins are usually in an extra pure form to insure good working properties....and that the resins you buy in your local home supply store can and will be industrial grade mixtures that can require experimenting to find the best working properties.
For the price difference, you come out far better by experimenting and arriving at your own personal choice of best resin.
Latex....well that's at your local hobby/craft store as well and one jar can easily do a hundred molds so just buy it there. You can save a few cents by ordering it from the web, but the savings aren't really worth the wait.
Mixing cups....if you plan to cast one head at a time then just save up all the old medicine bottles that you can find. One pill bottle will hold one head's worth of resin. If you plan to cast more than one head at a time or don't want to find the pill bottles....pick up a box of good old unwaxed "Dixie" cups at your local supermarket. The 4oz ones will pour two heads.
An obvious tip that most folks seem to miss....when using disposable cups, mark on the cups how much resin you use for each head. With the marks, you'll know exactly how much to use the next time and won't end up mixing too much or too little.
A word of warning about waxed cups....the wax can and will liquify in polyester type resins and will often leave a head with a tacky feel to it.
Experimentation is the key.
#2: Mold making
Go through your figures and select a head you like and jerk it off the figure. Different brands of figures require different methods of decapitation so BE CAREFUL!
A good guide to removing and switching heads....and a damned fine article on casting can be found on Rob's page.
Once the head is off of the figure, use some Fimo or Sculpy modeling clay to attach it flat to a small piece of cardboard as your base. Now apply your latex to the head as the container said....work in thin layers and allow drying time between each layer.
I tend to do multiple heads at once side by side so I can make a one piece latex mold and save time. It also let's you experiment a lot easier (more on that soon).
Tip: Latex is waterbased. To ensure that your first few coats are as close to perfect as possible, fill a pill bottle about halfway with liquid latex and then finish filling it with clean water. Mix that up well and be sure to cap it tightly between sessions. Keep that 50/50 mixture handy to do your first 2-3 coats on each of your heads and you won't have to worry about airbubbles in your mold.
Tip: If you have access to a food dehydrator....a finished mold can be done in a fraction of the time it would take for the latex to cure normally. As Rob mentions, a window fan can cut the drying time as well.
Once the dry latex mold is thick enough that it looks definitely yellow/brown and you cant see any of the head's coloring through it, dust it with talcum powder to stop it from sticking to itself. You'll then CAREFULLY peel/roll the mold down off of the head and your first mold is complete.
Here's where I part ways with all the other so-called "experts".
As I've said many times before....in any group of one hundred so-called "experts", you'll have maybe five who actually "know" the information and nintyfive who use those guy's knowledge to fake it. Casting is no different.
When teaching yourself something new....and that's what you'll be doing when you start casting....you have to look at it as a trial and error process. Don't look at any "how-to" article and assume that you know it all because you won't. You'll never become a true "expert" until you master the how-to articles and move beyond them into your own field of expertise.
Don't just read the instructions on the side of the can and assume that's the sum of all knowledge. Look at that can and see it as a starting point in your learning.
In that vein, take that first mold you made and mix the resin exactly like the can says....and write it down so that you can look back on all the successes and failures.
If you made a multi-head mold in the preceeding steps, pour the first one with resin that has half as much catalyst as the can recommends....the second with a bit more catalyst and so on. Or pour the first one with half as much mixing....second with a few more seconds of mixing and so on.
Once they're all cured....and they can produce a LOT of heat during the curing process....jerk them all out of the molds and see which ones turned out best in terms of detail and finish and such.
Don't worry if they all turned out like mutants....this is the experimentation stage that lets you produce perfect ones later. Just be sure to record your results so you can reproduce them later
You'll probably notice a few of them have tiny holes in the resin. That's where small airbubbles got trapped between the resin and mold. You can fix that by gently poking and sliding the point of a toothpick around in the detail areas of the mold once the resin is poured in. Removing airbubbles should be a usual step for you once you pour the resin....it always helps and never hurts.
If you decided to go for polyester resins, one thing you'll notice pretty fast....at a stage near the end when the resin was finally solidifying, the latex mold seemed to become loose and slippery on the resin head. That's called a "scum glaze". Sometimes the head will even stay sticky and scummy for hours after you cast it. Don't worry about it!
Scum glazing can be removed! Just wait until the head has cooled to be sure it's cured totally then drop it into a pot of boiling water for about fifteen minutes. The scum glaze will turn a milky color and soften to the point that it can be scraped off with a fingernail or toothbrush. Your underlying detail will be as clear and pristine as if it was made that way.
In my experimenting, I've found that my all-around favorite resin for casting heads is that same old Bondo polyester resin mentioned before. By varying the ratio of catalyst in each batch, I can make diffent colors too. By the use of additives, I can vary the texture and appearance too.
Adding a handful of talcum powder to the liquid resin, I can achieve an almost bone-like quality in the finished piece. By adding rock-tumbling media to the liquid resin I can achieve anything from bone/ivory to metalflake to concrete. Not too useful in heads, I agree, but great to know if you branch out to other subjects!
One thing to remember about industrial-grade resins like Bondo....always select the freshest can you can find on the shelf in the store! Shake each can a bit until you find the one that sounds thinnest and go for that one.
The key is to experiment and find out what you *can't* do....not to read a can or a how-to article and find out what you *can*.
You can use liquid vinyl "tool dipping" gunk to cast soft rubber items like hands and boots....but all the tries I took at it just took too long to cure. Along the same lines, polyurethane roof coating from the local Lowe's can be used for those same boots and hands but can take a few days to totally cure.
"Hot-poured" plastic....as in fishing worms....can be used for just about anything you can think of. One word of warning....those soft plastics will leak plasticizer and can eat certain types of plastic if they touch them.
Different roofing compounds can be way too thick to pour into a mold, but they *can* be used to actually make molds.
In all those experiments, you'll end up with some good items and some horrid ones. DON'T throw them out! Those mistakes with the airbubbles and the missing chin or ear can be used to sculpt your next masterpiece onto!
Here's a tip I try to explain to everyone who wants to cast their own heads....DON'T sculpt directly onto a vinyl head with Sculpy or Fimo! The vinyl will be destroyed in the process!
At the temperature that the Fimo and Sculpy have to be baked at, you force the vinyl to leak plasticizer. It may not look like it after you bake it once, but the vinyl degradation WILL become noticable soon enough. You'll end up with a head that's just a little bit less flexible than it used to be....or ever-so slightly shrunken....or it may just tear down the back when you try to put it back on the figure.
One of my favorite failures was a vinyl head I had sculpted a mustache onto....that one head went through the oven about four times before I decided to remove the Fimo facial hair. His upper lip was very noticably swollen-looking where the vinyl hadn't shrunk under the clay.
Sculpt onto a resin test head you produced in the earlier steps. The resin won't even notice the heat that Fimo and Sculpy bake at.
One thing to remember in each step....don't sculpt clay onto a head and bake it, then sculpt and bake again and so on. Sculpt a single detail onto a head and then bake it and mold/cast a few heads from it. Set aside any that have clay baked on for your masters.
eyebrows onto one of the resin heads you made and then
before moving on to the nose. Sculpt the nose onto one
resins with the eyebrows already in place and mold/cast
it and so on.
Those eyebrows you made may be perfect and the nose too....but you'll lose all that work if you mess up the mouth and have to start over. See my point?
In terms of aesthetics, a person tends to notice the more frontal positioned characteristics (nose, chin, and sometimes brows) first and most. If the guy you meet in the office has a strange nose, you'll notice and remember it longer than you will his ears.
You can use that tidbit of knowledge to make an infinite variety of different heads based on nothing but noses and so on. You can also use it to "fake" sculptures of famous people as you'll find out shortly.
Make a direct copy of a GI Joe head you happen to have and then cut/sand off the nose of a resin copy you make. Cast a few noseless heads to experiment on and start sculpting different noses onto them. You'll be amazed at how different each one looks after painting....and people will be amazed that you just produced fifty different heads in a weekend.
On famous people or characters you want to make....simply find the head that closest matches the one you plan to make and cast a few resins from it. Remove the nose/chin and so on and cast a few of those. Now go back and start sculpting the noses/chins back on until you get one that looks like the person you intended.
The simple fact....and it's almost disgusting in its implications....is that you can make an almost perfect likeness of a famous person simply by changing the characteristics that people notice. Match the characteristics they notice and they don't give a damn if the rest is generic.
People *do* in fact judge you by your appearance. Your nose is in fact too large and people will remember you by it. Your face is in fact so close to "generic" that even so little as a nose job can change your look.
Once you get to the point that your head looks good to you, make a good latex mold of it and cast a few following the formulas you arrived at in your experimentation stage....if people buy them then you were successful. If not, place that one on the shelf as a master and start over.
One simple trick I discovered during my years of casting....take the mold and just ever-so slightly deform it as the resin is jelling. Squeeze the jawline or press on the face/chin and so on. You can make some incredibly well-detailed customs of everyday heads you already have.
One other tip you can try that requires a bit more work....cast a few resins of heads you like and then cut them apart with a dremel or razor saw. Reassemble them with sculpy to hide the joints and cast a few of it to play with. You can make some damned fine customs that way and never really sculpt at all.
Experimentation is the key! Never be afraid to fail....failure teaches us what not to do the next time.
I'll go ahead and stop here since this got a bit longer than I had expected. If I missed a point or if anything isn't clear, then feel free to email us and we'll try our best to answer your questions.