Spider-Man (Peter Parker)
Spider-Man (Peter Parker)
Spider-Man's web-shooters are twin devices worn on his wrists which can shoot thin strands of special "web fluid" at high pressure. The web fluid is a shear-thinning liquid (virtually solid until a shearing force is applied to it, rendering it fluid) whose exact formula is as yet unknown, but is related to nylon. On contact with air, the long-chain polymer knits and forms an extremely tough, flexible fiber with extraordinary adhesive properties. The web fluid's adhesive quality diminishes rapidly with exposure to air. (Where it does not make contact with air, such as the attachment disk of the web-shooter, it remains very adhesive.) After about one to two hours, certain imbibed esters cause the solid form of the web fluid to dissolve into a powder. Because the fluid almost instantly sublimates from solid to liquid when under shear pressure, and is not adhesive in its anaerobic liquid/solid phase transition point, there is no clogging of the web-shooter's parts.
The spinneret mechanism in the web-shooter is machined from stainless steel, except for the turbine component which is machined out of a block of Teflon and the two turbine bearings which are made of amber and artificial sapphire. The wristlets and web fluid cartridges are mainly nickel-plated annealed brass. Spider-Man's web cartridge belt is made out of brass and light leather and holds up to 30 cartridges. The cartridges are pressurized to 300 pounds per square inch and sealed with a bronze cap which is silver soldered closed. The wristlets have sharp steel nipples which pierce the bronze caps when the cartridges are tightly wedged into their positions. The hand-wound solenoid needle valve is actuated by a palm switch that is protected by a band of spring steel which requires a 65 pound pressure to trigger. The switch is situated high on the palm and requires a double-tap to avoid most unwanted firings. The small battery compartment is protected by a rubber seal. The effect of the very small turbine pump vanes is to compress (shear) the web fluid and then force it, under pressure, through the spinneret holes which cold-draws it (stretches it: the process wherein nylon gains a four-fold increase in tensile strength), then extrudes it through the air where it solidifies. As the web fluid exits the spinneret holes, it is attracted to itself electrostatically and thus can form complex shapes. The spinneret holes have three sets of adjustable, staggered openings around the turbine which permit a single web line, a more complex, spun web line, and a thick stream. The web line's tensile strength is estimated to be 120 pounds per square millimeter of cross section. The 300 p.s.i. pressure in each cartridge is sufficient to force a stream of the complex web pattern an estimated 60 feet (significantly farther if shot in a ballistic parabolic arc).