IE does not require it.
Flexible urethanes are materials similar to low density polyethylene.
Rigid urethanes are general purpose and fit a wide variety of applications. These rigid urethanes have a UL 94VO rating and can be used in applications requiring flame retardant capabilities. Please contact your Project Engineer to evulate your particular application. Some material properties may be enhanced by customizing formulations or through post processing techniques. Contact your Solid Concepts' Project Engineer in order to select the best urethane casting material for your application.