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Evaluates the use of water‐based coating systems for industrial construction maintenance, as compared to the traditional, but more environmentally hazardous, solvent‐based systems. Concludes that, when an appropriate system is chosen, the performance of water‐based systems stands up to comparison with that of their conventional solvent‐based equivalents.

OUR fifty‐ninth volume is opened by this issue of the Library World, which has survived longer than any other independent library periodical. Some reflections, which may indeed seem repetitive, seem to be natural in the circumstances. We have a sense of gratitude to the number of readers, who as writers and subscribers have sustained us so long and will we trust continue to do so. From the first we have adhered closely to the thesis that our business was with the conduct of libraries and the activities, even personal ones, of librarians but not with their private affairs. We have endeavoured to initiate and to describe methods many of which are now commonplace in their acceptance. Thus J. D. Brown our founder and first Editor published in this his series on charging systems; Louis Stanley Jast his serial on his own cataloguing methods; Dr. E. A. Baker made known his views on the annotation of books; J. D. Stewart and Berwick Sayers wrote for those pages their study, afterwards published as the book The Card Catalogue—these are a few examples. The lighter forms of librarianship writing may be said to have been initiated in this country in our pages, for example the reports of the Pseudonyms' meetings which, it must be confessed, have a vague relation only to what actually took place at them; and the over‐thirty years' serial, Letters on Our Affairs, initiated in 1913 by one who became a world famous librarian, established, especially in its first decade, this style of critical writing which has had so many imitators.

Additive manufacturing (AM) has been one of the most highlighted processes of the last few years. AM prints complex parts and items from 3D files regarding different materials, such as polymers. Moreover, there are different AM techniques available for polymers, such as selective laser sintering. In the SLS technology, polyamides 11 and 12 lead 88% of the market. These materials are high-cost and use an average of 50% of virgin material at each printing. It is possible to use lower rates of virgin material, but at least 30% is recommended. Low rates of virgin material decrease mechanical properties.

This study aims to evaluate the influence on the mechanical properties of the percentage of reused PA12 in parts manufactured by the SLS process. The specimens of PA12 were manufactured with a percentage of virgin/reused polymer of 50/50, 40/60, 30/70, 20/80 and 10/90. We considered three distinct printing directions to compare the mechanical properties of the specimens: horizontal, perpendicular and vertical.

The results showed that when the percentage of reused material increases, the tensile strength limit (TSL), flexural strength limit and Shore D hardness decrease. Another aspect visualized was the fragile behavior presented in the vertical specimens. In addition, DSC analysis indicated a 2% reduction of crystallinity. Scanning electron microscopy images revealed spherical voids and unfused particles of PA12 at the fracture of tensile test specimens. The material thermal history and unfused particles could decrease the material properties.

We observed that the mechanical properties, such as the TSL, flexural strength limit and hardness, decrease as the percentage of reused material increases. In addition, the process presented a printing-direction dependence, where the vertical direction presented as the more brittle between the ones used.