An apparatus and a method which heat an elongated product in at least two pulses including at least one first pulse wherein the product is pressed for at least 10 ms on a first pressure and at least one second heating and smoothing pulse wherein the product is pressed and/or heated at least for 10 ms on a pressure that is higher than the first pressure. The heating elements being arranged to heat the elongated product so that the heating the heating temperature is at least 80° C. on at least one surface of the elongated product.