The blacksmith's forge is among the oldest manufacturing technologies in human history. The process is simple: heat metal to a temperature where it becomes plastic, then shape it with hammer blows. Forging compresses the grain structure of the metal -- the crystalline arrangement of the atoms -- and aligns it along the shape of the tool. A forged socket hoe has metal grain that runs from the top of the socket down through the blade. A stamped socket hoe has grain that runs perpendicular to the shape, because the sheet metal was pressed rather than struck.
Grain orientation determines where a tool fails. Metal fractures along grain boundaries, the lines between crystalline regions in the material. A forged tool, with its grain aligned along the stress path, resists fracture in the direction it is actually loaded. A stamped tool, with grain perpendicular to the load, fails more easily under the same force. This is not a marginal difference -- it is the difference between a trowel that bends slightly under a hard push and one that snaps off at the socket.
Drop forging -- the industrial version of blacksmithing -- places a hot steel blank between two dies and drops a ram onto it with tremendous force. The metal flows to fill the die cavities, compressing and aligning the grain in the process. The flash (excess metal that squeezes out between the dies) is trimmed, the part is heat treated, and the forgings are ground, polished, and assembled. This process is more expensive than stamping. It is also the only way to make a tool that handles the forces it will actually encounter.
The tell for a forged tool is weight and texture. Forged parts are denser than stamped parts because the forging process eliminates internal voids. Pick up a forged garden trowel next to a stamped one -- the forged version is heavier for the same physical size. The surface texture is different too: forge scale and grinding marks leave a surface that looks worked rather than pressed.
Casting -- pouring molten metal into a mold -- produces a different structure again. Cast iron has excellent compressive strength but poor tensile strength; it resists being pushed but breaks when pulled or bent. This is why cast iron skillets work perfectly but cast iron trowels would fail: the cookware is loaded in compression, the garden tool is loaded in bending and tension. Cast iron is the right material for cookware and the wrong material for most tools. Ductile iron -- cast iron with magnesium additives that prevent the formation of brittle graphite flakes -- is a better cast material but still inferior to forged steel for tools that take impact or bending loads.
The shift from forged to stamped tools happened in the mid-20th century when rising labor costs made the forge economically disadvantageous for commodity products. A stamped trowel can be made in a fraction of the time and at a fraction of the cost of a forged one. For someone who gardens occasionally, the difference may not manifest before the tool is lost or replaced anyway. For someone who uses a trowel daily for thirty years, the difference is the whole point.
The forged tool manufacturers who have survived the commodity shift did so by serving customers who knew the difference: professional trades, serious hobbyists, and the restorative buying impulse that made vintage tools a collector's market. Brands like DeWit, Bulldog, Gransfors Bruks, and C.S. Osborne have remained in business not by competing on price but by making the argument that a forged tool bought once is cheaper over a lifetime than a stamped tool bought five times.