INK-TRAP
Ink-trap measurement evaluates the ability of a printed ink
film to accept another ink film. If poor trapping occurs, color
shift will be apparent. Parameters that may influence the trap
are ink tack, print sequence, ink film thickness, blank pressure,
etc.
GATF (Preucil) Trap Equation:
% Trap (2 color) =
(D
op
- D
1
) x 100
D
2
Where:
D
1
=
1st ink density minus
paper density
D
2
=
2nd ink density minus
paper density
D
op
=
2 color overprint minus
paper density
Brunner Trap Equation:
(1 - 10
-(Dop)
) x 100
% Trap (2 color) =
(1 - 10
-(D1 + D2)
)
Where:
D
1
=
1st ink density minus
paper density
D
2
=
2nd ink density minus
paper density
D
op
=
2 color overprint minus
paper density
