How to distinguish between good and bad styrofoam quality

1. color：high-quality styrofoam is milky white after being punched out（snow-white kind）. it’s not good if the color is black, gray or extremely yellow( describes the use of cheap and inferior quality raw materials to reduce cost purpose). 2. thick：发 when the foam comes out,,bubble, not too thin or too thick,if the foam is too thin,…