line study

The da Messina one looks like its made of oak planks or boards - the flecking on the surface looks like truncated medullary rays which is the characteristic pattern found on radially cleft and hewn oak planks. Sawn planking would have a different grain pattern. It might be that the painter has used a convention to indicate radial oak which is a good quality material. Alternatively, the structure could be made of lower quality sawn plank which has been painted to look like oak.