Kropar-Vančina, Vesna; Černič-Letnar, Marjeta.
Durability of Coated and Uncoated Boards,
J. A. Bristow (Ed),
Advances in Printing Science and Technology, Vol 27,
Pira International Ltd, Leatherhead, 2001, (pp 41-55.), book with 263 pages
ISBN 1 85802 438 2

ABSTRACT
In this chapter the study of durability of coated and uncoated boards is described. The aim of the study was to determine the influence of board raw materials, technological conditions of production and surface treatment on durability and permanence by accelerated ageing according to ISO 5630/3 which is proposed by EN/ISO 9706 for materials on board with permanent value.
Eight coated and five uncoated boards of nominal grammage 250 g/m 2 were produced as two and three layer boards, consisted of virgin cellulose, CTMP wood and recycled fibres.Laboratory prints (CMYK) were prepared by IGT equipment for all investigated boards.
Basic, mechanical and surface properties of boards were studied, by standard methods for determination, as well as, their chemical and optical stability. Colour stability of laboratory prints was studied too. From the obtained results it can be concluded that the use of recycled fibres of undefined origin and of mechanical pulp fibres is adequate and recommendable for printing boards whose estimated lifetime does not exceed a few years. In the case of printed materials of durable value high-quality primary pulp fibres must be used in a neutral medium in the absence of optical bleaching agents and with calcium carbonate as alkaline buffer reserve.

KEY WORDS:
Accelerated ageing; Boards, Degradation of Boards,
Durability of Boards; Permanence of Boards;
Optical and Colour Stability.


Žiljak, Jana; Vančina, Vesna; Agić, Darko; Žiljak, Ivana; Pap, Klaudio.
New Screening Elements in Multi-Colour Printing for Special Purposes,
M. Lovreček (Ed),
Advances in Printing Science and Technology, Vol 30,
Acta Graphica Publishers, Zagreb , 2003, (pp 143-150), book with 261 pages
ISBN 953-96276-8-0

ABSTRACT:
This investigation determines new procedures of screening applied to multi-colour reproduction. Total individualisation of the image is obtained by introducing the new different screening system for each separation. This process is extended to the microstructure of the individual screening shapes, which were not described until now. Understanding of such procedures is closely linked to security printing, and therefore details are poor and not accessible. Solving of such problems involves team-work in various fields of research: design, prepress, materials in graphic processes, mathematical definition of screen system and shapes, as well as, protection methods for valuables. Proposed methods are performed by PostScript programming of output devices, optimal measurements and experimental digital printing, using special, as well as, conventional inks.

KEY WORDS:
New Screening Elements, Multi-Colour Printing,
Printing for Special Purposes


Babić, Darko; Kropar-Vančina, Vesna; Lajić, Branka.
Grooving Quality Research on Packaging Cardboard,
M. Lovreček (Ed), Advances in Printing Science and Technology, Vol 31,
Acta Graphica Publishers, Zagreb , 2004, pp 203-208., book with xy pages
ISBN 953-96276-9-9

ABSTRACT:
As far as boxes are concerned, a straight and clear edge is one of the most important aesthetic demands. This primarily concerns cardboard packaging used in the food and cosmetic industry, since buyers frequently have a direct contact with it. Such an edge can be obtained only if the folding point has been well prepared during the production process (punching). The research described in this paper has been carried out in order to prove that groove quality largely depends on the quality and climate conditioning of the cardboard used, as well as on the quality of grooving channels and tools used in the grooving process.Since the slightest change of the mentioned parameters causes a change in the quality of grooves, it is impossible to give simple instructions on how to make box blanks and/or grooves.After having analyzed the research results we can, claim with certainty that cardboard humidity as a function of relative air humidity greatly influences the quality of grooves. Since the parameters that influence groove quality are numerous, this research was restricted and focused on testing the quality of grooves moulded on channels made by CITO creasing matrixes System GmbH, Germany, VIKING iron grooving bands from Austria (dimensions: 23,30 mm high, 0.70 mm wide and 120 mm long) and KRAUSSE punching machine System GALLY, Germany (Fig. 2 and 3) .
The varying parameters were the grammage of tested cardboards (Table 1) , the conditioning of cardboards and height and width of grooving channels (Table 2) .
Grooving channels were adjusted to cardboard thickness (Table 2) .
Since the aim was to define cardboard properties as precisely as possible and to compare the grooving quality by observing the channels, we examined cardboard stiffness using a Taber tester (Table 3) . The results of stiffness were given in mNm. Stiffness is naturally influenced by cardboard thickness, which was also tested.
As was the case with other parameters, several measurements were performed, each of which was recorded as the average value expressed according to the ISO standards. For instance, cardboard samples weighing 280, 320, 350, and 450 g/m 2 were 0.35, 0.41, 0.44, and 0.57 mm thick, respectively.
When all the measurements had been performed, we compared the results, drew up tables and charts, and tried to establish the connection between the results obtained and the grooving quality. The results included additional commentaries, which aimed at explaining each value and conclusion as clearly and logically as possible.A proposed evaluation system based on the research results was designed: grooving channel quality was assessed according to a model table where attributive qualities were expressed through marks.The system was developed because every cardboard grooving quality research that had previously been conducted warned us about the need to transform the researcher's subjective impression regarding the box design or grooving quality into a more quantifiable assessment.It was, naturally, much of a challenge but we tried to produce an acceptable grooving quality evaluation model that might provide comparative material for any further research.Our experience and a great number of box blanks collected over the years and a substantial number of photographs proved to be great help in the process.Each category is accompanied by a photography, a descriptive assessment, and an explanation, which we hope will help avoid any mistakes that might be made when comparing grooving quality and the chosen evaluation model.

KEY WORDS:
Attributive Values, Grooves, Groove Quality, Packaging Cardboard


CURRENT CONTENTS PAPERS
Rožić, Mirela; Cerjan-Stefanović, Štefica; Kurajica, Stanislav; Vančina, Vesna; Hodžić, Emir
Ammonical Nitrogen Removal from Water by Treatment with Clays and Zeolites,
Water Research 34 (2000) 3675-3681.
Elsevier Science Ltd. All rights reserved
Printed in Great Britain
PII: S0043-1354(00)113-5

ABSTRACT
The objective of the present study was to investigate the removal of nitrogen in the form of ammonium ions (N-NH 4+ ) from aqueous solutions using natural clay and zeolite. The Croatian zeolite clinoptilolite fro the area of Donje Jesenje and Croatian bentonite clay from the Kutina area were used as natural filtration materials. Alkaline and acid modification of natural clay was performed. The N-NH 4+ removal efficiency by clays in a dry state as well as in a liquid colloidal state have been investigated. The highest removal efficiency value for N-NH 4+ (61.1 wt %) was achieved with the natural zeolite at the lowest used initial concentration, i. e. at a concentration of 100 mg N-NH 4+ /l. With the increase of the initial concentration of ammoniacal nitrogen, the removal efficiency quickly decreases. This is expected as zeolites and clays have limited sorption capacities. The practical aspect is important since an ammoniacal nitrogen elimination of more than 60.0 wt% for water containing less than 100 mg N-NH 4+ can be achieved. The ammoniacal nitrogen removal efficiency is higher for clays in a liquid colloidal state compared to the clays in a dry state. It has been found that the acid modification of the clay decreases the efficiency of ammoniacal nitrogen removal.

KEY WORDS :
Ammoniacal Nitrogen Removal,
Clay in a Liquid Colloidal State,
Natural Clay,
Natural Zeolite


Černič-Letnar, Marjeta; Kropar-Vančina, Vesna
The effect of accelerated ageing on graphic paperboards degradation,
Restaurator, 23 (2002) 118-132.
Copyright Saur, Munich
Printed in Germany All rights reserved
ISSN 0034-5806

ABSTRACT
Paper and board, now and most probably also in the future the most important carriers of written and printed cultural heritage, can be of very different permanence and durability, depending on their composition (fibres, fillers, sizing agents, dyestuffs, pigments) and on the technological conditions of production. We studied coated and uncoated boards from various producers and of the same grammage, (ca 250 g/m 2 ). The samples were submitted to accelerated ageing according to ISO 5630/3. From testing several chemical, mechanical, optical and surface qualities it become obvious that their retention depended mainly upon fibre composition and type of coating pigment. Low chemical and mechanical stability is proportional to the content of thermochemical pulp (TCP), chemo-thermo-mechanical pulp (CTMP) and recycled fibres. The change of surface properties is strongly influenced by the type of coating (binders, pigments). After ageing the surface roughness increased while absorbency both increased and decreased. The change in optical properties of the boards were quite high; brightness decreased while yellowness increased, both due to chemical changes in the fibre composition and the surface coating and due to the degradation of optical brighteners.

KEY WORDS :
Accelerated Ageing, Boards, Degradation of Boards, Fibre Composition,
Type of Coating,


Černič Letnar, Marjeta; Hladnik, Aleš; Kropar-Vančina, Vesna.
Optical and colour stability of graphic paperboards and prints,
Acta Graph. 15 (2003) 13-24. (Conference edition)

ABSTRACT
In the study we investigated the influence of surface treatment on permanence and stability of various graphic paperboard types - board for books, brochures, business cards, calendars, protection package - under the conditions of accelerated ageing with increased temperature and relative humidity in the absence of light according to ISO/5630/3, and as specified for materials on paper/board of permanent value by EN/ISO9706(8). Paperboards were coated with various coating colours, and subsequently lab printed in offset technique. The effect of artificial ageing on surface properties, as well as, on image optical and colour stability was monitored.
The changes observed in surface characteristics such as smoothness, roughness, air permeability, and absorptivity before and after the accelerated ageing process revealed a strong influence of coating components (pigments, binders) and surface treatment type. Increasing roughness, altering of board absorption behaviour and change in optical and colour parameters - decrease in brightness, increase in yellowness, colour shift with samples containing higher amount of optical brightening agents - were the most pronounced results.
Measured differences in printing colour (dE) and optical density values indicated that colour stability of offset image approached the limit values, which are set for an image of still acceptable quality. Black (K) exhibited the highest stability among CMYK colours. Image colour stability significantly depends on surface and optical board characteristics, especially on gloss and optical brightening agent, as well as, on board fibre composition and coating pigments.

KEY WORDS:
Accelerated Ageing; Durability; Graphic Paper and Paperboard Degradation;Principal Components Analysis; Surface, Optical and Colour Stability


Černič-Letnar, Marjeta; Kropar-Vančina, Vesna.
Optična in barvna obstojnost grafičkih kartonov in laboratoriskih odtisov,
Proceedings of the 27 th International Annual Symposium,
November 15 - 17, 2000 , Bled, Slovenia ,
DITP, Ljubljana , 2000, pp 133-140,
UDK 676 (063)


ABSTRACT
Paper and board as carriers of written cultural heritage remain important materials, so now days as in near and far future, because of their high permanence and durability. During the period of last ten years the book and document conversation, especially of those from the 19 th and 20 th century that show the signs of very quick decay in archives, libraries, museums, galleries all over the world, represents very important activities that demand quick and effective steps. We have studied coated and uncoated boards before and after accelerated ageing to determine the quality and durability of investigated boards. The durability of basic, surface and chemical properties, mechanical endurance, optical stability, as well as printability of boards were investigated. It can be concluded that retention of chemical, mechanical and optical properties depend mainly upon the board composition and type of coating. The low chemical and mechanical stability are proportional to the content of CTMP and recycled fibres.

KEY WORDS:
boards, CTMP fibres, recycled fibres, retention of board properties (chemical, mechanical and optical),


Bjelovučić Kopilović; Sanja; Jokić, Tigran; Kropar-Vančina, Vesna.
Introducing IT in Teaching the Engineering Design Graphics at the Faculty of Graphic Arts, University of Zagreb , Croatia ,
Proceedings of the 7 th International Design Conference – DESIGN 2002, Vol 2,
May 14 - 17, 2002 , Cavtat - Dubrovnik , Croatia ,
Faculty of Mechnical Engineering and Naval Architecture, Zagreb ,
The Deign Society; Glasgow , 2002, pp 965-974,
ISBN 953-6313-47-9
UDK 7.05 (063)

ABSTRACT
University of Zagreb published on May 28 th , a document " Leap 2001 " , The Development Strategy of the University of Zagreb (theses for discussion) by which the academic community is summoned to take its responsibility for improvement of the University in the process of the integration into European academic integrations. In this document SWOT analysis is given (Strengths, Weaknesses, Opportunities, Threats) of he current state, on which basis development aims are determined, expected outcomes are formulated along with difficulties and obstacles, and strategic steps to be undertaken. At the Faculty of Graphic Arts we educate students about possibilities and for using and applying of the IT already in the first year of study.
The results of the exams show that applied IT has helped the easier coping with curriculum, develops space perception, encourages creativity, enhances informatics literacy. A great attendance at the multimedia lectures, computer classrooms and numerous visits to the web-site are proofs of students ' satisfactory attitude towards these kinds and forms of lectures, which is one of the requirements of quality managing (to fulfil the expectations of services users, e. g. students). Future longitudal studies will give qualitative and quantitative indicators on final effects of our efforts.

KEY WORDS:
Colours, Education, Engineering Design Graphics, IT, Photorealistic Visualisation, Virtual Simulation, Web Publishing
Sanja Bjelovučić Kopilović, Vesna Kropar Vančina .
From Paper to Web and Viceverca Solutions for Educational Material,
Proceedings of the 29 th IARIGAI Research Conference,
Cross Media Publishing, Colour Management and Digital Proofing, Quality Control,
September 8 – 11, 2002 at the Lake of Lucerne , Switzerland ,
EMPA/Ugra, St. Gallen, 2002, pp 84-104,
ISBN 3-9520403-2-0

ABSTRACT
This article deals with some general problems related to specific conditions of university level education. The issue was elaborated on the example of the two courses at the FGA in Zagreb , Croatia . However, the approach and the results obtained could have general application in educational programs. Every year approximately 180 students that enrol FGA attend at the Chair of Mechanical Engineering the courses " Basics of Mechanical Engineering " and " Technical Mechanics " . In 1999/2000, the book that covered all the exercises in computer lab was published. In 2001/2002 this book was published at the Chair ' s web-site in three different formats (off-line PDF, on-line PDF and SHTML). Student ' s assignments were provided in form of GIF-images scanned from low quality printed items, and optimized both for web and for clearly printing. The choice of web-hosting provide, made after a sequence of trials, was crucial for accomplishing mentioned and all the other tasks provided at the web-site.

KEY WORDS:
Cross-Media Publishing, Education, Mechanical Engineering, Web Authoring, PDF


Černič Letnar, Marjeta; Hladnik, Aleš; Kropar Vančina, Vesna.
Effect of Accelerated Ageing on Degradation of Unprinted and Printed Graphic Paperboards,
Proceedings of the 29 th IARIGAI Research Conference,
Cross Media Publishing, Colour Management and Digital Proofing, Quality Control,
September 8 – 11, 2002 at the Lake of Lucerne , Switzerland ,
EMPA/Ugra, St. Gallen, 2002, pp 216 – 233,
ISBN 3-9520403-2-0

ABSTRACT
In the study we investigated the influence of surface treatment on permanence and stability of various graphic paperboard types - board for books, brochures, business cards, calendars, protection package - under the conditions of accelerated ageing with increased temperature and relative humidity in the absence of light according to ISO/5630/3, and as specified for materials on paperboard of permanent value by EN/ISO 9706 ( ∞ ). Paperboards were coated with various coating colours, and subsequently lab printed in offset technique. The effect of artificial ageing on structural and surface properties - mainly board/liquid interaction, as well as, on image optical and colour stability was monitored.
The chane observed in surface characteristics - smoothness, roughness, air permeability, absorptivity measured by classical and recent test methods, surface energy - during and after the accelerated ageing process revealed a strong influence of coating components (pigments, binders) and surface treatment type. Increasing in roughness, altering of board absorption behaviour and change in optical and colour parameters - decrease in brightness, increase in yellowness, colour shift with samples containing higher amount of optical brightening agents - were the most pronounced results.
Measured differences in colour (dE) and optical density values indicated that colour stability of offset image approached the limit values, which are set for an image of still acceptable quality. Black (K) exhibited the highest stability among CMYK colours. Image colour stability significantly depends on surface and optical board characteristics, especially on gloss and optical brightener agent, as well as, on paperboard fibre composition and coating pigments.

KEY WORDS:
Accelerated Ageing, Degradation of Graphic Paperboard, Durability and Permanence of Graphic Paperboard, Principal Component Analysis, Properties of Graphic Paperboard - Surface, Optical and Colour


Babić, Darko; Kropar-Vančina, Vesna; Černič-Letnar, Marjeta.
Investigation of the Relation Strength/Grain Direction of the Board Folding Box,
Proceedings of the 29 th International Annual Symposium,
November 13 - 15, 2002 , Bled, Slovenia ,
DITP, Ljubljana , 2002, pp 92-97,
UDK 676 (063)

ABSTRACT
The aim o this work was to investigate bearing capacity of small board boxes produced from the boards of 250 g/m 2 of different qualities. Somewhat lighter boards, than usually, were chosen with the intention that the strength of the material itself participates as little as possible in the obtained results. Small boxes were made from investigated boards; 10 boxes of each board 5 with grain direction parallel with the height of the box and 5 with grain direction perpendicular to the height of the box because such boxes has never been examined before. The testing of box strength was performed by the BCT method and Acquati ( Milan ) tester was used. Chemical, basic and mechanical properties of boards were carried out too in order to find out if there is any correlation between box strength and some properties of boards.

KEY WORDS:
BCT-Test, Board, Board Box, Box Blank, Grain Direction.


Babić, Darko; Kropar-Vančina, Vesna; Lajić, Branka.
Relation of Board Box Strength and Grain Direction,
International Conference MATRIB 2003, Conference Proceedings,
June 26-28, 2003., Vela Luka, Island Korčula, Croatia,
Croatian Society for Materials and Tribology c/o FSB, Zagreb , 2003, pp 1-6,
ISBN 953-7040-01-1

ABSTRACT
Modern food, chemical, and pharmaceutical industry pack their products in big transport corrugated board boxes, but they also use small bord boxes for individual commercial packaging. It is a common practice to make the grain direction of those small folding board boxes parallel to the box height, which creates large amounts of useless waste material in their production process in the graphic industry. This adds to box prices, but it also has negative consequences for the environment protection because it increases board consumption per box. The grain direction of big transport boxes is not the issue, but if this research proves that the folding board box strength is only slightly different when different height and grain directions are taken into account, and if the machines used in the production process react in the same way to those box types, we might be able to recommend to the graphic industry a new way of producing such boxes. The new production system would make a better use of board sheets by changing the grain direction, which, in turn, would make the production cheaper and would be ecologically better.

KEY WORDS:
BCT-Test, Box Blanks, Grain Direction, Tensile Breaking Strength.


Babić, Darko; Kropar-Vančina, Vesna; Lajić, Branka.
Impact of Cardboard Humidity on Groove Quality,
International Conference MATRIB 2004, Conference Proceedings,
June 23-25, 2004., Vela Luka, Island Korčula, Croatia,
Croatian Society for Materials and Tribology c/o FSB, Zagreb , 2004, pp 15-20,
ISBN 953-7040-01-1

ABSTRACT
Groove quality depends, among other things, on cardboard humidity. we varied cardboard humidity and quantity of grammes per square meter to se whether and to what extent cardboard humidity influences the quality of grooves. We also established the evaluation system which allows attributive qualities to be expressed through marks. Therefore, it becomes easy to assess and express through marks the quality of grooves, even in insulations and using only a graphic magnifying gas, which is a printer ' s usual tool. The research, which is an integral part our paper, was conducted through a visual analysis of photos of the grooves obtained. The results are given in tables.

KEY WORDS:
Attributive Values, Grooves, Groove Quality, Cardboard Humidity, Grain Direction.


Babić, Darko; Kropar-Vančina, Vesna; Jurečić, Denis.
Bearing Capacity of Board Box and Grain Direction,
Annals of DAAAM for 2004 & Proceedings of the 15 th International DAAAM Symposium,
3 rd -6 th November 2004 , Vienna , Austria ,
DAAAM International, Vienna, Austria, pp 017-018,
ISBN 3-901509-42-9

ABSTRACT
In this work 6 boards of small (250 g/m 2 ), medium (350 g/m 2 ) and higher (450 g/m 2 ) grammage and different qualities were investigated by Taber method (ISO 2493). Small and medium boxes were made from all investigated boards with grain direction parallel and perpendicular with the hight of the box. Bearing capacity of all boxes was performed by BCT method. From the obtained results of BCT tests it can be concluded that the box strengths are, almost, the same in both directions A (MD) and B (CD).

KEY WORDS:
BCT test, Bending Stiffness, Box, Grain Direction.


Mikota, Miroslav; Kropar-Vančina, Vesna; Mitrović Kukoč, Branka.
Usporedba dominantnih tehnika ispisa digitalne fotografije na optimalnim podlogama,
Zbornik radova 8. savjetovanja tiskarstva, dizajna i grafičkih komunikacija,
Blaž Baromić,
Lovran, 23. - 24. rujna 2004.,
Grafički fakultet Sveučilišta u Zagrebu i
Ogranak Matice Hrvatske Senj, Zagreb , str. 93-100,
ISBN 953-96020-2-5

SAŽETAK
Sustav digitalne fotografije može se definirati kroz snimanje, učitavanje i kompjutorsku obradu snimljene digitalno zapisane fotografije te njezin ispis. Ispis se digitalne fotografije danas ostvarje različitim tehnikama od kojih su dominantne ink jet, sublimacijska te ispis fotografskim printerima. Za ovaj je rad snimljena testna digitalna fotografija koja je ispisana ink jet printerom CCMMYK tehnologije,
subliaciskim te fotografskim printerom. Uz testnu su digitanu fotografiju ispisana i definirana špolja za denzitometriju i kolorimetrijsku kontrolu.
Za svaku je tehniku ispisa korištena odgovarajuća podloga (Epson in jet photo paper, olympus passport photo paper za sublimacijski ispis, fotografski papir Agfa Prestige) te ostali standardni materijali. Prije ispisa podloge su uspoređene s obzirom na površinsku masu, debljinu, glatkoću i stupanj bjeline.
Ispisane testne fotografije ocijenjene su vizualno. Na osnovi kolorimetrijskih mjerenja određena su odstupanja boja ( ∆ E) zadanih primarnih boja i crne, a denzitometrijski su određene optičke pokrivenosti za cijan, magentu, žutu i crnu boju.
Dobiveni rezultati ukazuju na različitosti ispisa digitalnih fotografija s obzirom na tehniku ispisa te problematiku odnosa fotografije prikazane na monitoru kompjutora, što je najčešće osnova u fazi obrade digitalne fotografije i finalne fotografije, tj. ispisa.

KLJUČNE RIJEČI:
digitalna fotografija, ink jet printer, sublimacijski printer, fotografski printer, razlika boja


Černič-Letnar,Marjeta; Kropar-Vančina, Vesna; Scheicher, Leopold.
Optična obstojnost grafičnih kartonov,
Grafičar, 2 (2001) 14-23.
ISSN 1318-4377

POVZETEK
Rezultati raziskave so pokazali, da je za bolj obstojno gradivo trajnejše vrednosti potrebno uporabljati karton iz kakovostnih surovin, pri optimalnih tehnoloških pogojih izdelave, ki ustrezajo standardom in priporočilom za trajnejše in arhivske namene uporabe. uporaba recikliranih vlaken nedefiniranog izvora in uporaba lesovinskih vlaken je primerna in priporočljiva za tiste vrste grafičnih papirjev in kartonov, pri katerih želena trajnost uporabe ni več kot nekaj let, medtem ko je gradivo, ki predstavlja trajno vrednost, potrebno uporabiti kakovostne primarne vlaknine pri izdelavi v nevtralnem mediju, brez prisotnosti optičkih belilnih sredstev in ob uporabi kalcijevega karbonata kot alkalne puferne rezerve.

KLJUČNE RIJEČI:
kalcijev karbonat kot alkalna rezerva, obstojnost gradiva, optička belilna sredstev, vlaknine,