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planning a steel armature
May 30, 2006
choice of metal for armatures
by sven at 8:00 am
It appears that there are mainly just four metals used in creating metal-jointed armatures:
- Brass: Easy to find, easy to cut, easy to braze. Seems only to be used in amateurs' armatures. Reacts badly with foam latex, due to there being copper in the alloy. The armature can be wrapped or sprayed to protect the latex, but it's still a risk.
- Steel: A strong material, but rather heavy. More difficult to find -- need to go to professional metal suppliers, rather than hobby stores. Brazes easily. Can be used safely with foam latex. Sparks when cut.
- Aluminum: Lightweight. More difficult to find -- need to go to professional metal suppliers, rather than hobby stores. "Cannot" be brazed; pieces are generally secured using very small screws (4-40 or smaller). Typically requires a milling machine -- not just drilling and cutting. Aluminum balls not recommended for ball joints: too soft. Can be used safely with foam latex.
- Phosphor bronze: Noted as having a particularly "smooth" feel. Material is difficult to find -- needs to be special-ordered, even from a pro metal supplier. Reacts badly with foam latex, due to there being copper in alloy. Even among professional armaturists, it seems esoteric; its use may (?) have come from the Trnka studio.
If you want to make armatures at the pro-level, steel seems to be the standard. I suspect that this is primarily due to it being safe for use with latex. Aluminum has the advantage of being lighter -- but this is counterbalanced by the fact that it's difficult/impossible to braze.
I'm in the process of collecting the materials that I'll need for making a steel armature. Even if I'm just a hobbyist, I'd like to do pro-quality work. And I'm interested in steel just for the sake of experiencing different materials hands-on.
However, I've begun to question the assumption that steel is necessarily superior to brass. If I understand correctly, brass works fine with silicone. Brass is easier to find than steel, and doesn't spark when you cut it. So, if you're making silicone puppets, shouldn't brass be the preferred material?
I have a suspicion... For a very long time, foam latex was the pinnacle of pro puppet-making. Foam latex puppets require steel armatures. Silicone is relatively new on the scene. I suspect that people still feel that steel is the "professional" and "superior" material -- but only because they haven't disentangled the actual needs of the casting materials from what kind of armature is required.
I was very interested to read this on an SMA thread:
[Henry] Selick recently mentioned, in an interview relating to his work on "Life Aquatic", that he's basically abandoned foam latex in favor of Dragon Skin, which is silicone based, I believe.
It looks like silicone may be the future. ...Perhaps brass is the future, too?