When the collector temperature is not sufficient to maintain the jet in a liquid state, and collector speed is less than the jet speed, the jet rapidly solidifies and, due to compression forces, it forms "arch shaped" structures. Figure illustrates this effect resulting from variable printhead temperatures and highlights this behavior under extreme conditions (collector at room temperature). As shown, the nylon-12 jet begins this arch shape formation when the collector temperature is at 130°C and the printhead temperature drops below 210°C. This effect was previously observed with high melting point polymers or when highly concentrated silk aqueous solutions were printed by electrowriting into a frozen collector .