Porcelain Buchner funnels include fixed perforated plates. Funnels are glazed on inner and outer surfaces except for the rims. Resistant to thermal shock with an average coefficient of expansion from 20 degrees C to 200 degrees C is 3.56 x 10-5, gradually increasing to 4.69 x 10-5 at 1050 degrees C. Every batch of porcelain is heat tested in our factory. No glaze-softening occurs up to 1000 degrees C and it is extremely white. Resistant to acids and alkalies, except for hydrofluoric acid. Capacity 350ml. 1 per pack.