The distinction between land rent and land value capture reveals why the object is unstable. One tradition observes the whole field of urban land value and asks how rent should be taxed or distributed; another focuses on increments associated with planning decisions and infrastructure. Both depend on a theory of causation. Value cannot be captured fairly unless institutions can explain which part of an increase is socially produced, which is attributable to location or scarcity, and which emerges from private investment and risk. Yet conversion is never purely fiscal. Governmentality analysis shows that the calculations used to represent value are themselves instruments of governance. Residual valuations, land prices, infrastructure budgets and feasibility models translate heterogeneous qualities into commensurable figures. These technologies make action possible, but they also exclude what cannot be easily priced. Social, ecological and aesthetic values enter redevelopment only when institutions construct channels through which they can survive financial calculation. Public land development offers one such channel. Municipal ownership can connect land allocation to developer obligations, sustainability criteria, collaboration and learning. It can transform the land transaction into a platform for defining desired public outcomes. The Swedish cases demonstrate that this capacity reaches beyond infrastructure provision, while also exposing a conceptual problem: not every public benefit can be traced to a discrete increment of captured value. Public value is wider than value capture. Place quality makes this tension explicit. The comparative evidence from Scotland, the Netherlands and Germany shows that planning systems and land-policy strategies affect whether uplift can be channelled into public realm and placemaking. Active land policy can internalise quality costs earlier and reduce uncertainty, but no instrument guarantees durability. The decisive analytical question becomes not simply what is captured, but what the captured value becomes and whether that outcome persists. For Socioplastics, value conversion makes finance, regulation, land, design and maintenance readable within one infrastructural chain. A corpus can follow the movement from development right to valuation, from valuation to obligation, from obligation to spatial outcome, and from outcome to long-term maintenance or erosion. This is stronger than treating value as a monetary category because it makes conversion itself observable. Value conversion adds to Socioplastics a political economy of transformation: a method for tracing how institutional decisions turn abstract uplift into concrete public conditions, and where that transformation succeeds, leaks or disappears.