According to the invention, there is provided a method of compressing an uncured man-made vitreous fibre web, the web having two opposed major faces. The method comprising the steps: passing the web along a path; and subjecting the web to thickness compression by applying compression to the two major opposed faces of the web. Compression of each of said major faces of the web is applied by passing the path between converging continuous or discontinuous compression surfaces. Further, the respective major face of the web that is being compressed is in contact with one of the converging compression surfaces, and said converging compression surface is inclined towards the path. Additionally, each inclined converging compression surface applies an amount of compression to the major face of the web with which the respective inclined converging surface is in contact, wherein the amount of compression applied to at least one of the two opposing major faces of the web is adjustable.