Yes, it was partical board. The same thing that melemine sheets are made out of but it did not have the melemine coating. Most coutertops are made out of partical board so I was just thinking with the formica top and bottom, with solid 2" partical board that it would be pretty stiff. The MDF is 31.95 / 4x8 sheet here and so I thought this may save some money. When I lived up in Kalispell, Plum Creek sold their seconds on MDF for $1.00 sheet from the mill. Most sheets were good, just not cut right or had a variance in thickness.