Resin
From CosplayWiki
Resin Refers generically to any product that begins in a liquid state, but can be rendered solid through some hardening catalyst. Resins are used anywhere a rigid structure is needed in cosplay. In their liquid state as well as during the curing process, nearly all resins are extremely toxic. They should only be only be used under adult supervision, with proper safety measures in place.
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Types of Resin
there are actually dozens of types of resin used in modern industry. Only a few of them are feasible or common for use in cosplay.
Polyester
This is the most inexpensive of the resins, as well as the most easily attainable. Polyester resin is very foul smelling and should only be used under extremely well ventilated conditions. In its liquid form, polyester resin is a common component in fiberglassing. Polyester resin however contains styrene monomers which dissolve solid polystrene plastics. Before using over styrofoam, the surface must be fully sealed off using some sealant like latex housepaint. Polyester resins dissolve readily in acetone. A thickened formulation of polyester resin is sold as Bondo putty which has an easily spatulated consistency that lends itself well to both surfacing props like armor, as well as modifying the form of prefabricated objects.
Polyester resin should only be used in thin layers due to the high heat created from the curing process. Building up layers of polyester resin too thickly, or allowing the resin to rest in a cup for too long can actually cause the resin to smoke or spontaneously combust. The high heat can also cause already solidified resin to warp, distoring the prop.
Epoxy
Thickened forms of epoxy resin are attainable at any hardware store as two part adhesives. Liquid epoxy resin is also used in fiberglassing. It is more expensive and harder to find than polyester resin, but it is stronger and far less pungent in oder. Epoxy resin also does not dissolve polystrene, so it may be used over foams without the need to seal off the foam.
Slow set epoxy gels are excellent to use in creating a mirror-smooth surface on products like wood. It can also be brushed onto leather to produce a homemade rigid patent leather.
As with polyester resin, thick layers can cause temperature buildup capable of warping or cracking a prop surface.
Polyurethane
Polyurethane resin is also referred to as "liquid plastic". Unlike Epoxy or Polyester resins, liquid plastic resins may be used for casting molded props. Molds may be made from a variety of materials including latex and silicone. Polyurethane resin comes in a wide variety of formulations that provide variations in strength, weight, setting time and viscosity. Some formulations for example can be used in a technique called rotocasting, where a mold filled only partially with resin is rotated constantly until set. This produces a lightweight hollow prop, making the technique good for producing props like helmets.
Polyurethane resins can discolor and weaken under prolonged exposure to UV light. Products made from polyurethane resin should either be painted, treated with UV protective sealant sprays, or stored away from sunlight.
