Heating and MHD quantities of the representative cork A in fibril 1 as functions of time. In each panel the cork formation period defined by the upswing of the photospheric box oscillation is shaded a lighter grey and the fibril destruction period is shown in a darker grey. Panel a: heating rate divided by internal energy density Q/e for work done by energy diffusion (magenta), compression (cyan), Joule heating (brown), radiation (blue), viscosity (green), and their sum (red). Panel b: mass density (thick blue), as well as the average mass density at the height of the cork (thin blue). Panel c: temperature. Panel d: magnetic field strength (blue) and plasma β (red).