| 摘要 |
A security paper comprises a fibrous base layer with regions of normal base fibre density incorporating a watermark in the form of a continuous line or band, extending from a darkest region at one end to a lightest region at the other end. The darkest region is formed by more densely deposited fibres and the lightest region by less densely deposited than the normal base fibre density. The density of fibres is varied to produce is a continuous change of tone between the lightest and darkest regions. The grammage at the darkest region may be at least 140% and at the lightest region no greater than 25% that of the normal fibre density regions. The paper may include a second watermark with the same grammage as the first watermark in the lightest and darkest regions. The watermark may be formed by an element portion having a combination of a raised solid region 28 gradually reducing in height and running into a sunken channel region 60 gradually increasing in depth in an element comprising an integrated body having drainage channels 23 which may be varied in shape, size, spacing or distribution. |
