We describe a mathematical model to evaluate flammability parameters of thermally thin thermoplastics in radiative ignition experiments. The concept of a critical mass flux from the solid phase into the flame is used as the criticality condition. Kinetic parameter values are chosen by relating the Arrhenius parameters to the ＇characteristic temperature＇ that is measured in Thermogravimetric experiments (TG). The specific application of our model we have in mind is piloted ignition in the Cone Calorimeter.