Macroscopic defects:

3-dimensional macroscopic defects are known as bulk defects. They commonly occur on a much larger scale than the microscopic defects. These macroscopic defects commonly are introduced into a material during refinement from its raw state or in during fabrication processes.

The most general bulk defect arises from foreign particles being involved in the prime material. These second-phase particles, known as inclusions, are seldom needed since they significantly alter the structural properties. Instances of an inclusion might be oxide particles in a pure metal or a bit of clay in a glass structure.

Other bulk defects involve gas pockets or shrinking cavities found commonly in castings. These spaces weaken the material and are thus guarded against during fabrication.  The working and forging of metals could cause cracks which act as stress concentrators and weaken the material. Any welding or joining defects might also be categorized as bulk defects.