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Sandwich application is commonly used in the windows graphics market, but it can be very attractive for

other applications done with transparent media (flexible or rigid). It consists on printing an image A, then on

top of it a white layer and finally on top of the white layer and image B (which could be the same as A if

desired). Thus, images A is visible from one side of the media and B is visible from the other side of the

media. One of the main challenges to obtain a good sandwich output is the opacity provided by the white

layer between the color layers because if this layer is not enough opaque one image might be seen mixed

with the other image and you don’t want this effect. It is not a matter of quantity of white. Obviously if you

put 4 drops of white the opacity will be higher than when you put only 2, but there is a point of saturation

of our ink and the opacity doesn’t change although you put more ink. This limitation (or saturation point) is

not specific to latex but also present in competitors as UV inks. To solve this problem a layer of black color

can be added as following: print image A, white layer, black layer, white layer and image B in this order. This

black layer prevents transparency between sides and provides full opacity.

Some UV competitors already have a 5-layer sandwich solution among their features. In order to close this

competitive gap, a 5 layers mode was strongly required for the latex R-series but the current pipeline was

not able to handle such a high number of planes. In order to overcome this technical limitation, the proposed

invention reuses the information of some of the planes to map it, after some smart masking

implementation, to the proper colorant trenches of the printhead to finally generate a 5-layer sandwich

mode printmode.

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