Dear all

We got a strange effect, when we matt laminated offset printed job. Colour of skin was normal at printed sheet, but it turns really reddish after lamination. Different was not small. It had never happened to us before. Usually laminated job turns to be little bit yellowish, not reddish.

At the first I thought that there was some chemical reaction between magenta ink and glue of laminate or heating of lamination effect to magenta. But I measured dot gain and checked what process colour there are at skin tone. Dot gain of laminated sheets was about 5 % higher than unlaminated. At this skin tone there was mainly only magenta and yellow ink. Result of higher dot gain of both yellow and magenta causes reddish tone, compared to tone where there are all cmyk inks causes only darker tones.

Do you have any experience, is this just because optical phenomenon of uneven surface of matt laminate plastic? Does this happen with gloss laminate? How do you deal with it? It is not easy to assume to what tone lamination will effect strongly. Most of case (99.9 %) lamination does not change tone so strongly. Then to use special lamination ICC profile to all laminated job is not possible?