Strawboard

From PyroGuide

Strawboard or yellow cardboard is a high quality paper made from rice straw as the raw material. In contrast, common brown or grey cardboards (chipboards) are made from pulp or waste paper. Strawboard has a higher tensile strenght than ordinary cardboard of the same thickness.

Disks, plugs etc. made of strawboard are frequently found in consumer fireworks, as these tend to come from China mainly where the material is still widely used. Non-plastic shell hemispheres popularly sold by pyro suppliers are also made of strawboard which is put into shape in hemispherical molds. Shimizu mentions the existence of imitations of strawboard where papers of inferior quality are sandwiched between two thin layers of the yellow material.