Security Thread
A narrow polymer or metallic stripe embedded in a paper web during the paper manufacturing process. It is verified in transmitted light.
Types of security threads:
- a latent security thread is completely embedded in paper;
- a windowed (diving) security thread appears partially on the paper surface. In reflected light it looks like a dashed line, in transmitted light — like a solid dark stripe.
Security threads may be colored and may incorporate microprinting, optically variable, UV and IR luminescent features.
a
b
c
Fig. 1. Poland. Passport issued in 2001:
a — page 1; b, c — the same. Latent security thread. Transmitted light (b). Cross section of a document page (c)
a
b
c
d
Fig. 2. Kosovo. Passport issued in 2011:
a — page 17; b, c, d — the same. Latent security thread. Transmitted light (b). IR light (c). RKS microprinting on the security thread (d)
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b
c
d
Fig. 3. Russian Federation. Passport issued in 2010:
a — page 45. Windowed metallized security thread with a colour shifting effect; b, c, d — the same. Transmitted light (b). Color change effect (c, d) at different angles of observation
a
b
c
d
Fig. 4. Sweden. Emergency passport issued in 2011:
a — front side; b — the same. MOTION® security thread. UV light; c, d — the same. Transmitted light (c). White light (d). The image of a plane moves when changing the angle of observation or illumination (d)