windows in the resulting paper optionally the wire mesh 15 may also include an additional embossing 18 e g in the form of a human portrait which will create a type of watermark in the final paper if required where the wire 11 passes beneath cylinder 14 the wire 11 follows an arcuate path to take into account the curvature of the cylinder 14 the continuous flexible security element in the form of a strip or thread 20 to be fed into the paper is generally of uniform construction and thickness such a thread 20 is typically 12 micron polyester vacuum metallised with aluminium on one or both sides and coated on one of those sides with a protective and or adhesive material obviously other designs or compositions may be used according to the desired end effect the preferred security strip or thread is typically but not exclusively 1 5 mm wide but again the actual size will depend on the required effect the thread 20 is fed from a bobbin 21 over a guide mechanism 22 in the direction of arrow c the guide mechanism 22 is positioned such that the thread 20 makes contact with the raised portions 16 of wire mesh 15 above the level of the paper being formed and maintains tension of the thread in operation aqueous fibrous stock is fed from a supply 23 via the mouth 13 of head box 12 to form a generally even layer 24 water from the layer of stock 24 drains through the holes in the wire 11 thus leaving fibres deposited on the wire 11 and.