What material is used to create portal-conductive surfaces in Portal?

Moon rocks are used to create portal-conductive surfaces in Portal.

In the Portal universe, ordinary walls cannot generally accept portals; the portal gun requires specially prepared surfaces. Aperture Science develops a white portal-conductive paint made with ground moon rock or moon dust. This material is spread across surfaces so that the blue and orange portals can attach to them.

Portal 2 turns the material into an important part of Cave Johnson’s backstory. Johnson describes Aperture’s moon-rock experiments with characteristic enthusiasm, but prolonged exposure damages his health. The company’s research therefore links a useful gameplay material to the founder’s decline and to the increasingly reckless culture of Aperture Science.

The wording can cause confusion because the game often refers to moon dust, while trivia summaries commonly call the ingredient moon rocks. Those expressions point to the same fictional material: lunar rock processed into a usable powder and mixed into portal-conductive paint. Concrete, titanium, and diamond are not the named materials associated with this technology. The moon surface itself can also accept a portal during Portal 2’s finale, but that is a separate gameplay event.