If you would like to write for this, or any other Emerald publication, then please use our Emerald for Authors service information about how to choose which publication to write for and submission guidelines are available for all. Please visit www.emeraldinsight.com/authors for more information. About Emerald www.emeraldinsight.comEmerald is a global publisher linking research and practice to the benefit of society. The company manages a portfolio of more than 290 journals and over 2,350 books and book series volumes, as well as providing an extensive range of online products and additional customer resources and services.Emerald is both COUNTER 4 and TRANSFER compliant. The organization is a partner of the Committee on Publication Ethics (COPE) and also works with Portico and the LOCKSS initiative for digital archive preservation. AbstractPurpose -The purpose of this paper is to evaluate and discuss colour properties, stability and lightfastness after accelerated exposure in xenon-arc light apparatus, of 3D ink jet prints produced by using 3D colour printing process. Design/methodology/approach -3D colour prints were produced using ZCorporation 3D printing method. The samples were divided into groups according to the finishing process applied (untreated, finished with different infiltrants). Colorimetric properties were measured using spectrophotometer. Samples were placed into xenon-arc based weathering apparatus (Xenotest), using the preset glass filtered sunlight, standard indoor conditions. Colour stability was evaluated as change in colour after repeating the spectrophotometer measurements and comparing spectral and specific colorimetric values of initial and exposed samples. Findings -Based on methodology used, the analysis has shown the changes in colour appearance of differently finished 3D prints, which were mostly attributed to chroma and lightness variations. The colour stability of samples studied noticeably varied and is dependent on colour, percentage of ink coverage and finishing method. Issues of colour and stability of 3D ink jet prints could become important as 3D printing emerges into new application areas, in which the object properties will need to be maintained for a certain amount of time.Research limitations/implications -The research is comparative and is limited to the specific materials and procedures used. Originality/value -The paper describes aspects of colour 3D printing for which the published research and literature data are still, for the most part, lacking. Colour measurements methodology and evaluation of stability described could be of value for further research and for users of the technology.

Colour changes of a thermochromic liquid crystal (TLC) ink printed on a black substrate are clearly observed by the naked eye, and therefore it is reasonable to expect that every approach recommended for colour measurements of samples with solid colour would be appropriate. In addition, the published spectroscopic analyses of TLC inks do not provide any guidance or limitations for the measurement geometry. On the other hand, our study demonstrates that spectroscopic measurements of such samples are not so straightforward. When using the most simple and commonly used measurement equipment with a directional illumination and viewing approach, the temperature‐dependent spectral features resolve in a narrow spectral region that gives only a small part of the colour play effect. Detection of the entire effect requires the use of integrating spheres, which spatially integrate the radiant flux reflected on a sample in any direction; better results are obtained by spheres of larger diameter. The comparision of spectroscopic and colorimetric results obtained when different measurement geometries are applied on the same sample may demonstrate certain properties of the liquid crystal material inside microcapsules and help in understanding some details of the optical properties of the ink layer.

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Efficient end-of-life solutions play an important role in developing sustainable packaging because they contribute to reducing resource wastage and environmental impact, whilst providing economic and social benefits. This paper briefly reviews current end-of-life solutions for fibre and bio-based materials for packaging in Europe. It also addresses current research in the field, as well as standardization, legislation and socio-economic aspects related to renewable packaging in Europe. This review focuses on the following groups of packaging materials: paper and board and bioplastics. With this hierarchy, recycling, organic recovery and energy recovery are analysed with regard to the processes and technologies that offer the most sustainable end-of-life options.