Item from Worm by Wildbow
The PRT's standard-issue parahuman restraint — a fast-expanding chemical foam sprayed from canisters that hardens into a rigid shell. Non-lethal, effective against most capes, and ubiquitous in the setting.
Containment foam is the great equalizer — the tool that lets unpowered PRT troopers engage parahumans with some hope of success. It expands rapidly, hardens quickly, and is breathable but immobilizing. Most capes can be contained long enough for transport. Brutes can eventually break free. The foam is everywhere — built into PRT buildings, carried on patrol, deployed in Endbringer fights. It's Tinker-derived but mass-produced, one of the rare Tinker inventions that scaled. Its ubiquity makes it a background constant of the setting, as standard as handcuffs in a cop show.
A viscous white-yellow substance that rapidly expands on contact with air. It hardens within seconds into a rigid, slightly translucent shell. Sprayed from handheld canisters, turret-mounted dispensers, or grenade launchers. The foam has a faintly chemical smell and a texture like hardened insulation foam.
Also known as: confoam, foam