What types of material can microwaves pass through?

Materials that have low dielectric loss characteristics, such as borosilicate glass (not soda lime glass) paper, most plastics. Air is also transparent. read more

Microwaves can pass through a lot of materials: Pretty much anything except for conductors, and even then, if there's sufficiently large holes, the microwaves can pass through the holes. read more

Microwaves can pass through body but losses and scattering is very high as compare to transmission. Relative permittivity of human body is complex and function of frequency. Due to this fact transmission, scattering and losses of microwaves in human body is also function of frequency. read more

The microwaves also pass through paper, plastic and similar materials - that is why one can cook with such materials in a microwave oven. Microwaves however do not pass through metal objects, but rather often cause arching in a microwave oven, and thus can not be used in a microwave oven. read more