Some types of permanent magnets are compacts of very small particles. Their properties depend largely on mutual magnetic influence between particles or groups of them. To determine these, more should be known about packing arrangements, orientation, separating layers, and the homogeneity of the compact. A method is described which makes surface details visible and simultaneously reveals magnetic phenomena of such compacts. The size of the compacted particles mostly requires the resolving power of an electron microscope. Special replicating techniques combine shadow‐graphing and colloid application even on rough and porous surfaces.Examples are presented of such surface studies on barium ferrite and iron‐cobalt particle magnets. Surfaces of barium ferrite magnets with crystal sizes of 0.2–1 &mgr; show indications of magnetic domains smaller than observed before, sometimes with less than 0.1 &mgr;‐width. On compacts of small elongated iron‐cobalt particles, structures have become visible which indicate particle groupings varying with the methods of compacting. Colloid outlines surface pole arrangements in correlation to particle groups.