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This paper presents the results of research conducted within R&D project. The primary goal was to apply the current state of the art technology in aluminium to a timber-based frames, but also to improve the energy performance of the building envelope and create environmentally friendly product, which physical, structural and aesthetic performances are equal to or even better than equivalent aluminium systems. The developed TimberCW is an innovative structurally glazed curtain wall system entirely comprised of laminated timber profiles incorporated in a fully prefabricated unitised curtain wall design, where glass panes are bonded by the structural silicone to timber frames. While most current timber curtain wall systems are stick designs, combined with aluminium elements, this new concept introduces timber split mullions and entirely eliminates aluminium structural members, whilst maintaining high weathertightness performance. In order to retain thin cross sections, as they are common for aluminium design, specialised corner connections in timber frame and stainless-steel bracketry has been developed and laboratory tested. Comparative energy efficiency analysis and condensation risk assessment of the TimberCW vs fully unitised aluminium systems of identical overall geometry and structural performance are presented. Full scale laboratory testing has been undertaken and certification obtained, proving the TimberCW concept suitable for project application.

The roof of the Zagreb Cathedral, dating from the general reconstruction in 1890-ties, withstood the 2020 earthquake in Croatia with remarkably good resilience. However, the restructuration project after the quake initiated extensive activities on the condition survey and consideration of possible measures for ensuring the future longevity, structural stability, and seismic resistance of the structure. The assessment encompassed the determination of wood species, anatomical structure, hygrotechnical conditions, as well as physical, mechanical, and biological properties of wood and load-bearing capacity of timber. It was demonstrated that visual grading and density measurements on drill cores proved adequately chosen main inputs for determining mechanical properties. The (quasi) nondestructive testing (NDT) - stress-wave, screw withdrawal and resistance drilling - proved useful additional methods yet fully effective only in combination with microscopic evidence on cores. A newly developed method of fairly invasive but completely re- constructive sample withdrawal of 50×50×800 mm beams yielded the MOEstat and standard test values on small clear samples (bending, MOEstat, shear ǁ and compression ǁ). NDT tests and small clear samples varied in conformity and measurement uncertainty but usefully complemented the main results and indicated the required corrections in mechanical classification. Special attention was paid to the detailed survey and analysis of timber joints and the consequent stability of the structure in the future. Dead loads, snow loads, and wind loads were considered in structural analysis models. Also, the history of seismic responses was also analysed. Such analyses form a sound base for the technical design of reinforcements as well as necessary repair and reconstruction measures of the roof structure.

Hrastovina predstavlja izuzetno vrijedno turopoljsko prirodno bogatstvo, a njezina uporaba za gradnju je pogotovo važna zbog izvrsnih mehaničkih svojstava i visoke postojanosti prema vremenskim djelovanjima i biološkoj razgradnji, što osigurava dugotrajnost drvenih građevina ili dijelova njihovih konstrukcija. Kakogod, i ovako visoka trajnost zahtijeva tehnički nadzor i mjere održavanja, pogotovo na građevinama koje predstavljaju spomeničku baštinu. Pristup ocjeni stanja povijesnog drva je specifičan kako po metodologiji, tako i po interpretaciji rezultata, jer o njemu ovisi projektiranje nosivosti i funkcionalnosti klasičnih drvenih konstrukcija. Primjeri analize stanja krovišta baroknih crkava u nekim turopoljskim mjestima demonstriraju osnovne korake u ocjeni stanja povijenoga drva: identifikaciju vrste drva, mjerenje fizičkih i mehaničkih svojstava drva radi izračuna nosivosti elemenata, analizu biološke razgradnje i iskaz zaostalog nosivog presjeka elemenata, te ocjenu geometrijske pravilnosti i tehničke ispravnosti konstrukcije i pojedinih spojeva. Odabrani rezultati trebaju prikazati s kojom se brigom i predviđenim zahvatima obnove proučava stanje hrastovih krovnih konstrukcija u postupcima potresne obnove nakon 2020. godine.

Laboratorij za drvo u graditeljstvu (LDG) Fakulteta šumarstva i drvne tehnologije Sveučilišta u Zagrebu akreditiran je za ispitivanja drvnih građevnih proizvoda, boja, lakova i ljepila. Nakon potresa 2020 godine, međutim, laboratorij je naglo proširio i razvio djelatnosti u području dijagnostike drva i drvenih konstrukcija u postupcima obnove, u kojima zaštićena kulturna dobra predstavljaju posebno značajan segment graditeljstva radi specifičnosti pristupa njihovoj obnovi i zaštiti. S jedne strane, kulturno dobro se treba, po mogućnosti, sačuvati u izvornom obliku i stanju te u maksimalnoj mogućoj ili dopuštenoj mjeri. U tom smislu metode koje se ovdje primjenjuju moraju biti bilo neinvazivne, bilo minimalno invazivne odnosno praktično nerazorne, s mogućnošću zadržavanja izvornog oblika konstrukcije i stanja materijala. S druge strane, sve praktično primjenjive mjerne ili ispitne metode imaju ograničen doseg djelovanja, pa je donošenje zaključaka o stanju cjelokupne konstrukcije na temelju lokalnih mjerenja komplicirano i zahtijeva posebno razmatranje vrste i broja uzoraka, načina izuzimanja uzoraka i njihovog baratanja te smislenu analizu značenja dobivenih rezultata. Naposlijetku, nerazorne metode često imaju vrlo malu pouzdanost, pa je neophodno razmotriti značaj njihovih pokazatelja i rabiti usporedbu više metoda za ishođenje relevantnih zaključaka. Velik dio ispitivanja i mjerenja, kao i izuzimanje uzoraka, provodi se na zgradama, i to metodama koje nisu akreditirane, a neke nisu niti normirane. Prezentacija prikazuje kako iskustva stečena u postupku akreditacije laboratorija pomažu u kreiranju i provođenju neakreditiranih ili nestandardnih ispitivanja. Primjerice, način validacije metoda, razmatranje rizika, kontrola mjerne točnosti i pouzdanosti rezultata stečeni u laboratorijskoj praksi i rigoroznom usavršavanju u postupcima akreditacijskih nadzora, pomažu prilagodbi akreditiranih metoda mjerenjima in situ, međusobnoj usporedbi i vrednovanju rezultata dobivenih različitim metodama, te mogućnosti iskazivanja ocjene stanja drva i konstrukcije radi izrade projekta obnove. Neke akreditirane metode se pažljivo modificiraju za mjerenje izvan laboratorijskih uvjeta: normirano mjerenje sadržaja vode drva, njegove gustoće te mehaničkih svojstava prilagođavaju se zatečenim izvan- laboratorijskim uvjetima ili nestandardnim uzorcima (izvrtcima iz specijalnih krunskih svrdala, izradi mikro-mehaničkih uzoraka i slično). Mjerenje anatomskih i bioloških svojstava drva mora se prilagoditi dostupnosti ispitivanih dijelova zgrade, specifičnim uvjetima klime, osvjetljenja, stanja površine i slično. Naposlijetku, potrebno je razmotriti uspješnost posrednih metoda u iskazivanju svojstava drva: primjerice, rezistografskim mjerenjem zaključiti o svojstvima gustoće i mehaničke cjelovitosti, čvrstoćom izvlačenja vijaka zaključiti o gustoći drva, akustičkim ili vibracijskim metodama zaključiti o mehaničkim svojstvima drva potrebnima za budući izračun nosivosti konstrukcije. Sustav akreditacije uvelike pomaže da se ovakve aktivnosti provode s najvećom mogućom savjesnošću i pouzdanošću te time podiže renome i prepoznatljivost laboratorija u važnoj ulozi osiguranja podloge projektiranju sanacije i osiguranju trajnosti drvenih dijelova oštećenih zgrada.

Pojmovnik hrvatskog drvnotehnološkog nazivlja rezultat je rada na projektu Izgradnja hrvatskog drvnotehnološkog nazivlja (DRVNA), koji je financiran u okviru programa Izgradnja hrvatskoga strukovnog nazivlja (STRUNA-05- 2016). Pojmovnik sadrži 1445 preporučenih hrvatskih naziva iz područja drvne tehnologije i još 930 hrvatskih istoznačnica (dopušteni, nepreporučeni i zastarjeli nazivi te žargonizmi), a riječ je ujedno i o trojezičnom pojmovniku drvnotehnološkoga nazivlja jer su svi pojmovi popraćeni i s 1886 ekvivalenata na engleskome jeziku i 1770 na njemačkome jeziku.

Durability of wood windows is especially important issue in times when energy efficiency, natural resources management and carbon cycle of products have great value. It greatly depends on several important factors: material selection, physical protection and detailing, surface protection, installation and regular maintenance. Moisture content and its distribution over the cross section of window frames directly influences dimensional (in)stability, particularly bowing and distortion. Therefore, the scope of this work was to monitor the distribution of moisture content of wood windows during one year period in order to get detailed insight into the influence of site orientation to the risk of degradation of wood.

TimberCW is an innovative structurally glazed timber curtain wall system entirely comprised of glued laminated timber profiles incorporated in a fully prefabricated unitised curtain wall design. The system eliminates aluminium elements whilst maintaining high weathertightness performance. Specialised corner connections and stainless steel bracketry has been developed and laboratory tested. The target in the research of the TimberCW was to apply the current state of the art technology in aluminium to wooden based frames and to improve the energy performance of the building envelope. The developed system is an environmental friendly, with physical, structural and aesthetic performance equal to or better than equivalent aluminium systems.

Heat treated wood (HTW) is successfully applied for floorings due to its better moisture resistance, increased dimensional stability, and uniform colour change to darker, brownish colours. The aim of this work was to define the hygroscopic range and equilibrium moisture content at ambient conditions of heat treated wood of two wood species – ash and beech. Material was treated at two temperature levels, 190 and 210 °C, and the properties were compared with native wood. The reduction in dimensional changes is expressed by volumetric shrinking and Anti Shrink Efficiency (ASE). Additionally, parquet elements were made out of such HTW, oil-impregnated and waxed, and subsequently tested for water vapour and liquid water permeability. Shrinking gradients of HTW were not reduced in comparison with native beech wood, but the absolute reduction in water uptake resulted in cca 50 % lower EMC values and up to cca 60 % improved ASE values. Surface treatment further improved the hygroscopic properties of HTW.

The scope of this research was to monitor the distribution of moisture content of wood windows during one year period in continental part of Croatia. Measurements were taken on several different windows placed on comparable positions of the family house facing east, west, north and south. All the windows were partially protected with the roof overhang, leaving their lower parts exposed to weathering. There were 6 measuring positions along each window frame. In order to get the insight into the moisture content distribution over the cross section of the frame, three pairs of electrodes with insulated shafts were used at each measuring position. The results of the measurements in the outer zone of the frame indicate that, during one year period, the lowest maximum moisture content was detected on the window facing south (14, 5%), east (16, 5%), west (19, 5%) and the highest maximum was measured on the window facing north (21%). Minimum moisture content values also differ significantly, depending on the side of exposure. The lowest and the most uniform moisture content in inner zone is measured in south position (10 - 12 %), and the highest and widest moisture content range was detected in north (13 - 17 %). The distribution of moisture content between the outer, mid and inner zone also depends on the exposure side, the lowest differences were measured in south and the greatest in the north side. The greatest differences over the cross-section (up to 6%) were detected during winter period and the smallest (1 - 2 %) in summer. To minimise seasonal fluctuations of moisture content in wooden windows it is essential to follow the basic rules of physical protection, and pay due attention to proper installation and maintenance.

Numerous studies of wood weathering phenomena led to good general knowledge regarding principle breakdown processes during exposures. However, results obtained using different methods are incoherent and dependent on the particularities of the testing method applied. In order to better understand the processes which happen on and under the wood surface during weathering as well as to identify the most influential wavebands of light causing photodegradation of wood, several weathering tests (artificial and natural) were performed. Batches of thin strips of fir wood, assembled in packs of matching three strips (thus forming a 240 m thick surface layer), were exposed to irradiation behind a set of cut-on glass filters that transmitted selected regions of the UV and visible spectrum in the range of wavelengths from 295 up to 515 nm. Weathering regimes included different light sources and various levels of climatic conditions (temperature and relative humidity of air). Discoloration developed disproportionally faster in early phases of exposure ; finite span microtensile strength reached saturation in the middle of the exposure period, whereas zero span strength and chemical changes reached their maxima at the end of exposures. This practically means that, different methods revealed different nature and extent of "damage" in specific phases of exposure and only the combination of results can give a complete image of the process.

Utjecaj vlažnosti zraka na kvalitetu drvenih podova česta je tema profesionalnih diskusija među podopolagačima, građevinarima i drvnim tehnolozima. Zna se da drvo, kao higroskopski materijal, prima vlagu iz zraka, a posljedice mogu biti bubrenje i deformacije - kako elemenata, tako i cijele podne plohe. Često se, međutim, ne zna točno koliko je značajno (tj. izraženo), te koliko je jako i brzo (tj. intenzivno) djelovanje povišene vlage zraka na drvo. Problem je naročito izražen pri polaganju drvenih podova, tj. potrebom utemeljene ocjene podobnosti uvjeta za pravilnu izradu poda, ali ćemo vidjeti da njegov značaj ne prestaje niti u uvjetima u uporabi.

Determination and estimation of the moisture content in the wood is of the great importance for the proper and efficient conducting of wood production processes, and thus the achievement of desired quality of final products. Electric resistance type wood moisture meter is the most commonly used in production process for estimation of moisture content in wood, so it derived an idea to find a simple way for control of its accuracy and reliability. The precision of electrical resistance type wood moisture meter is measured by gravimetric method for the determination of moisture content. This simple method is designed, developed and tested at the Faculty of Forestry, University of Zagreb within the European IPA project Increasing competitiveness of Croatian industry of wood flooring on the EU market. The paper presents the method developed for control of accuracy of wood moisture meter, and the results of interlaboratory control of accuracy of electrical resistance wood moisture meters according to developed method.

Hrvatska drvna industrija proizvodi drvene podove visoke kvalitete, no da bi zauzela ravnopravno mjesto na tržištu potrebno je zadovoljiti neke formalne zahtjeve. Iz toga razloga se javila potreba za unapređenjem postojećih sustava kontrole u proizvodnji koji su jedan od preduvjeta u postupku CE označavanja proizvoda. Na projektu vrijednom gotovo pola milijuna eura pod nazivom „ Povećanje konkurentnosti hrvatske industrije drvenih podova na EU tržištu“ surađuju Laboratorij za drvo u graditeljstvu Šumarskog fakulteta Sveučilišta u Zagrebu (LDG) i proizvođači drvenih podova u Republici Hrvatskoj. Uz razvoj novih ispitnih metoda, iz projekta je financirano i opremanje novog Laboratorija za drvo u graditeljstvu, edukacija proizvođača drvenih podova, provedba ispitivanja u tvornicama drvenih podnih obloga te međulaboratorijska ispitivanja sa Sveučilištem u Grazu i Sveučilištem u Ljubljani. Projekt odgovara i općim i specifičnim ciljevima IPA programa za regionalni razvoj jer osigurava izravan prijenos znanja i tehnologije sa Šumarskog fakulteta u drvnu industriju jer se povećanjem istraživačkih i komercijalnih kapaciteta fakulteta poboljšava suradnja između znanosti i industrije u radi ispunjenja njezinih izravnih potreba. LDG predstavlja najvažniji javni i neovisni ispitni i tehnički centar za industriju drvenih podova u Hrvatskoj, s glavnim fokusom na razvoj tehnologije. LDG je dobro upoznat s potrebama industrije drvenih podnih obloga i drugih građevnih proizvoda od drva jer uspješno njeguje dugogodišnju suradnju s 14 tvrtki od kojih se njih 10 bavi proizvodnjom drvenih podova. Regionalni aspekt je posebice izražen imajući na umu da šume prekrivaju preko 40% teritorija Republike Hrvatske, stavljajući sektor šumarstva u jedan od najvažnijih tradicionalnih industrijskih faktora nužnih za gospodarski razvitak i ekonomski rast. Industrijske ciljne skupine obuhvaćaju proizvođače drvenih podnih obloga od kojih je većina smještena u područjima od posebne državne skrbi sjeverne i istočne Hrvatske. S približno 1000 zaposlenih, ova industrija zadržava većinu stanovništva u regijama orijentiranim preradi drva i predstavlja vitalan ekonomski faktor za lokalnu zajednicu i njezinu dobrobit.

Hardness and density of the wood are considered to be among the most important technical properties of wood flooring. There are standardized methods for determining specified properties, but in factory conditions they are rarely used. The reason is that they require expensive specialized equipment, a large number of test samples, trained staff, and they are relatively long lasting. For these reasons, there was a need for simpler, faster and less expensive method to determine the above mentioned properties of wood. This paper explores the possibility of substitution of the standard methods for determining Brinell hardness with the method of the relative size of the impression (RSI), and also the possibility of substitution of standard test methods for determine wood density (ISO 3131: 1975) with method of measuring the mass of floor elements whose volume is known. The aim of the research is finding a scientifically based, simpler, faster and cheaper ways of determining the aforementioned properties of wood. Innovative methods have proven to be very simple and useful with satisfactory results for practical use.

Formulacija, uvođenje i poboljšanje tvorničke kontrole kvalitete (FPC) izravno poboljšava tehnički i tržišnu moć hrvatske industrije drvenih podova. Vanjska institucija koja je upoznata s važećim zakonskim propisima može ponuditi potrebnu pomoć putem obrazovanja, tehničkog savjetovanja i uspostavljanjem boljih industrijskih postupaka ispitivanja/kontrole. Očekuje se da će šira profesionalna zajednica usvojiti upute za FPC i primijeniti sustav kontrole u svojim tvornicama.

TimberCW - a frame system of spatially laminated wood profiles was designed that enabled the construction of fully unitised structurally glazed curtain wall units for the envelope of high-rise buildings. The system was analysed, full-scale laboratory tested and certified. The goal in the development of the TimberCW was to develop an environmental friendly system with 0% aluminium content, having physical, structural and aesthetic performance equal to or better than equivalent aluminium systems. Comparative thermal transmittance analysis and condensation risk assessment of the TimberCW vs fully unitised aluminium systems of identical overall geometry and structural performance are presented.

Osnovni pokazatelji kvalitete površine svih masivnih drvenih lakiranih podova su adhezija (EN 14354), otpornost na udar (EN 13696), elastičnost (EN 13696), otpornost na trošenje (EN 13696), otpornost na ogrebotine (EN 438-2) i otpornost na razne tekućine (EN 13442). Iako su ispitivanja normirana, njihovi rezultati sami po sebi malo govore o kvaliteti proizvoda krajnjem korisniku jer predmetne norme u pravilu ne propisuju referentne vrijednosti. Ispitni laboratorij stoga ima dvojaku ulogu u procesu ispitivaja: da provede tražena ispitivanja, te da po potrebi načini interpretaciju rezultata i razredbu prema normama za srodne proizvode kako bi krajnji korisnik lakše donio odluku prilikom odlučivanja o kupnji. Srodni proizvod u predmetnom slučaju mogu biti furnirane drvene podne obloge (EN 13454). One se ispituju po istom principu kao i masivni podovi, a njihova norma ujedno donosi i kriterje za razvrstavanje proizvoda u dva osnovna razreda uporabe - privatni i javni, te još tri podkategorije s obzirom na intenzitet opterećenja prostora - umjeren, normalan i jak. Primjerice, spavaće sobe predstavljaju primjer umjerenog privanog (kućnog) prometa, dnevni boravci su primjer normalng, a blagovaonice i hodnici primjer privatnog prostora jakog intenziteta.

The aim of this work was to define the influence of density of beech wood of different densities to hygroscopic range, equilibrium moisture content (EMC) at ambient conditions, shrinking and swelling coefficients as well as to anti shrink efficiency. For the experimental purposes samples were prepared to form the following variables: wood species of different density, ring orientation (structure), and treatment level. For density tests beech wood samples were prepared from material of distinctively different density ranges marked as B1: (0, 612 – 0, 642 – 0, 666) g/cm3, and B2: (0, 705 – 0, 715 – 0, 734) g/cm3. Laboratory tests implied weight measurements, along with length and width measurements in three pre-defined positions on every sample. Separate panels of tangential and radial structure served for measurements of dimensional changes over their width. Shrinking coefficients of HTW were not reduced in comparison with native beech wood. However, the significant reduction in absolute water uptake resulted in significantly lower EMC values and improved ASE values of HTW. Heat treatment only slightly reduced the density, and the paper brings its influence to physical properties of wood floorings.

This paper describes an investigation into the influence of temperature on photodegradation rates in wood. Ten different softwood species were subjected to artificial weathering in the Xenotest 1200 at temperatures of 25, 35, 45 and 55 C for periods of up to 400 hours. The rates of photodegradation were determined for each species at the different temperatures by monitoring the loss in microtensile strength. Photodegradation rates for the different species were shown to be temperature dependent and to increase with rising temperature. The tests appeared capable of discriminating between the photoresistance of the various species. Arrhenius plots for the species were linear with activation energies in the range 5, 9-24, 8 kj/mol. It is concluded that the test methodology has the potential to differentiate the susceptibility of different wood species to photodegradation.

To attain and emphasize natural aesthetic advantages of both native and modified wood, its surface should be protected with transparent or semi transparent finishing systems whose durability should be improved. Particularly the identification of wavelengths of ultraviolet and visible light during weathering that cause the changes in colour and micromechanical properties of wood, was chosen to be the principal interest in this research. Batches of thin strips of fir wood, assembled in packs of matching three strips (thus forming a 240 m thick surface layer), were exposed to irradiation behind a set of cut-on glass filters that transmitted selected regions of the UV and visible spectrum. Disassembling the pack of three strips after withdrawals from exposure enabled monitoring of the relevant changes in each particular strip i.e. in the depth of the wood surface during weathering. Depth profiles of colour and microtensile changes develop in time and are specific to observed properties. Relatively narrow waveband of most active wavelengths is causing greatest proportion of all recorded damages (360 – 435 nm). However, visible light of wavelengths up to 510 nm was shown to contribute significantly to surface damaging. Efficient protection of wood from light would demand screening not only UV light, but also some violet and blue light wavebands. The light protection must be efficient over prolonged periods of time in order to secure long-lasting stability of wood surface.

Effects of standard artificial radiation sources (xenon-arc and fluorescent-UV) were compared with natural sunlight to determine activation spectra of four parameters of wood surface photodegradation. Photodegradation effects regarding colour, microtensile strength at zero and finite initial span, as well as chemical changes developed with different intensities in various stages of exposure. Discoloration developed disproportionally faster in early phases of eposure ; finite span microtensile strength reached saturation in the middle of the exposure period, whereas zero span strength and chemical changes reached their maxima at the end of exposures. This practically means that, despite very similar character and extent of colour changes, different light sources produced different activation spectra in specific phases of exposure. Activation spectra for retained zero span strength of top strips were very similar in all three exposures. Activation spectra of lower strips were not well differentiated. Relatively narrow wavebands of most active wavelengths between 360 and 435 nm caused greatest proportion of damages. However, visible light of wavelengths up to 510 nm was shown to contribute significantly to surface damages. The observation of interrelationships of different weathering regimes and assessment methods of photochemical processes gave valuable insight into the complexity of the process and brought new findings about the nature of light-induced breakdown of unprotected wood. This knowledge may be employed in further studies of the degradation of this natural polymer, but also in finding new solutions for enhancing light fastness of wood and formulations of protective chemicals and coatings.

Service life of wood building products should be understood as carbon sink and extended to its possible maximum. Surface deterioration presents one of major problems. Identification of most detrimental wavebands of UV and visible light causing the complex chemical and physical changes involved in the photodegradation process is essential for a development of efficient light protective systems. Batches of thin strips of fir wood were exposed to irradiation behind a set of filters that selectively blocked UV and visible light. Depth profiles of color, microtensile and chemical changes develop in time and are specific to observed properties. Waveband from 360 to 435 nm is causing greatest proportion of all recorded damages, but visible light of wavelengths up to 510 nm should not be neglected. This shows that filtering only narrow wavebands of light may improve efficiency of light protection of a wood product and directly extend its service life and more sustainable living environment.

The wavelength sensitivity of unprotected fir wood surfaces was assessed using a series of glass cut-off filters under which three 80 μm thick radial wood strips formed a composite surface layer of wood exposed to xenon light. Colour and microtensile changes in the different layers followed different patterns and intensities. During exposure, the colour and microtensile changes shifted ever deeper into the surface and further into the visible region of the spectrum. A relatively narrow waveband of most active wavelengths was causing the greatest proportion of the recorded photodegradation (360 – 435 nm), whereas visible light of wavelengths up to 515 nm also contributed significantly to surface damaging. This is an important finding, assuming that the current knowledge implicitly assumes that the actinic effect of light progressively increases with a reduction in wavelength. As a consequence, an efficient protection of wood from photodegradation would demand also screening longer wavelengths of UVA light and some violet and blue light wavebands of the visible part of the spectrum.

Rad donosi pregled svih relevantnih činitelja kvalitete lakiranih podnih obloga, načine ispitivanja i tumačenje ispitnih rezultata s ciljem boljeg razumijevanja ispitnih izvješća od strane proizvođača materijala, distributera proizvoda, podopolagača i krajnjih korisnika proizvoda.

Testing methods that simulate the traffic loads of lacquered surfaces in use are standardized, but not all of them define minimal requirements or reference values of particular properties in use. This creates problems for technologists and end consumers in meeting and understanding the quality criteria for particular products. The paper presents the survey of the characteristic test methods and respective testing results for most important properties of the lacquered wood flooring element according to new Croatian standards. The presentation should aim at better understanding of results and contribute to the formulation of the classification tables for relevant properties of wood flooring elements.

Heat treated wood (HTW) can be successfully appllied for floorings due to its better moisture resistance, increased dimensional stability, and uniform colour change to darker, brownish colours. The aim of this work was to define the hygroscopic range, equilibrium moisture content (EMC) at ambient conditions, density and biological durability of heat treated parquet elements of hornbeam, ash and beech. Material was treated at two temperature levels, 190 °C and 210 °C, and the properties were compared with native wood. The reduction in dimensional changes was expressed by volumetric shrinking and Anti Shrink Efficiency (ASE). Additionally, parquet elements, produced from HTW, were oil-impregnated and waxed, and subsequently tested for water vapor and liquid water permeability. Shrinking coefficients of HTW were not reduced in comparison with native beech wood. However, the significant reduction in absolute water uptake resulted in ca 50 % lower EMC values and up to ca 60 % improved ASE values of HTW. Heat treatment only slightly reduced the density of all species tested, but significantly improved their biological durability. This biological resistance was drastically influenced by treatment temperatures above 190 °C. Surface treatment with flooring oil and wax further improved the hygroscopic properties of HTW parquet elements.

This paper shows the microscopic evidence (obtained by scanning electron microscopy - SEM) of the structural degradation of wood caused by weathering. Typical damage on radial and tangential surfaces of softwoods due to natural or artificial exposure is presented. The order of appearance of particular structural changes enables the distinguishing between various levels of degradation according to the occurrance and intensity of the changes on certain anatomical features. Subsequently the conditions of the coating, of the substrate and of their link were assessed after exposure of coated samples. Two types of European softwood species were used as a substrate, namely pine and spruce, and they were used either as coated panels or as microtomed wood sections ('thin strips'), which were exposed behind a detached film of a coating. Solvent borne (sb) coatings were compared with modern water-borne (wb) coatings. Semitransparent stains were compared with opaque white paints. The paints did not penetrate the cell wall but firmly adhered to the S3 layer of the lumina. The solvent-borne coatings (both paint and stain) penetrated deeper into the wood surface than the water-borne coatings.The opaque paints fully protect the wood from the effect of light through a 14-month period of natural exposure and maintain the coherent protective coating. The water-borne paint exhibits more brittle characteristics on the fractured transverse surface than the solvent-borne paint. The stains vary in their protective effectiveness. The thick water-borne stain shows a tough, sound failure mode, good adhesion but very poor penetration into wood surface. The thin coating of the solvent-borne stain is degraded by light, and the interface with the wood is affected, resulting in the development of brittleness of both wood and coating and leading to adhesion failures preceding the detachment of the film.

The article presents a new method for determination of the optimum surface tension in adhesives (glues and wood varnishes). The criterion employed is maximum work of adhesion. In view of the fact that work of adhesion depends, among other things, on the free surface energy of wood and the surface tension of the adhesive, and that the free surface energy changes in relation to roughness, this experiment was carried out on three groups of specimens of beech wood with radial surface. One group of specimens thus had a sanded surface, the second group consisted of planed pieces, while those in the third group had a surface worked out with a steel hand scraper.Work of adhesion can be good criterium for determination of optimum surface tension because it take into consideration adhesiv, adherent and their interaction. The roughness of wood surface was measured and expressed as the average arithmetic deviation of the surface roughness profile Ra. The wetting angle Q was also measured for nine liquids with different levels of surface tension. On the basis of the wetting angle and surface tension the critical surface energy of wood (gC) was calculated, as well as the work of adhesion (Wa), the optimum surface tension of the liquid wetting the wood surface in question ( gL, G, opt) and the maximum work of adhesion (Wa, max).

Iako pregrijano drvo iskazuje izuzetne prednosti u smislu estetskih svojstava (jednolična i efektna promjena boje) te nekih tehničkih značajki (jako smanjeno bubrenje i utezanje te poboljšana otpornost na gljlive), treba biti svjestan i njegovih nedostataka u odnosu na normalno drvo. Mehanička svojstva bitno su smanjena, tako da se ovaj materijal uglavnom rabi za nenosive konstrukcije i za parket, a površina je osjetljiva na izbjeljivanje na svjetlu i pojavu pukotina. U svakom slučaju potrebno je razviti iskustva o reakciji svake vrste drva na pregrijavanje, jer se pokazalo da reagiraju vrlo različito, te na odnos fizikalnih odrednica postupka obrade i posljedičnih promjena na drvu.

This paper presents the results of testing of several transparent exterior wood finishing systems with increased hydrophobic and light-stabilizing properties. The assessment of protective efficacy was based on natural exposure with evaluation of colour change and other aspects of general appearance. Contact angle measurements were done on the coated surfaces and the water vapour permeability and the liquid water permeability of coating materials were assessed. It has been established that the contact angle values do not fully express the behaviour of the surface in moist conditions. Only one of the tested materials exhibits the level of water impermeability that would enable its use for dimensionally stable wood products (such as windows and doors) where a limit for water absorption is set to 175 g/m2.

U radu je dan pregled izlaganja i komentari sa skupa o drvnim premazima "Enhancing Service Life" održanom 2006. godine u Pragu.

Several surface treatments for transparent protection of exterior wood have been tested in natural and artificial weathering by measurements of contact angle, liquid water and vapour absorption, colour change and mechanical properties ("thin strip" method). Pine and spruce wood was impregnated with HALS-containing primer and subsequently treated with UV-modified, nano-scaled hydrophobic emulsion, or by application of several transparent coatings. Hydrophobic properties ("pearling effect" and high contact angles) did not correlate well with water absorption, and the weathering resistance depended on the amount of UV additives and film thickness. Providing that sufficient depth of primer penetration and resistance to vapour transport are assured, transparent coating systems containing HALS, UV absorber and nano-based water repellent offer very promising enhancement of exterior wood service life.

Heat treated wood is successfully appllied for floorings due to its better moisture resistance, increased dimensional stability, and uniform colour change to darker, brownish colours (tones). The aim of this work was to define the hygroscopic range and equilibrium moisture content at ambient conditions of heat treated wood prepared for parquet elements out of two wood species – ash and beech, heated at two temperature levels. The reduction in dimensional changes of heat treated wood compared to untreated is expressed by volumetric swelling and shrinking.

Europske norme postavljaju strože zahtjeve na odrednice kvalitete drvenih podnih elemenata. Predlaže se razvoj povećanjem tehničke kvalitete parketa, razvoja proizvodnje predgotovljenih, površinski obrađenih podnih elemenata, parketa od pregrijanog, kemijski modificiranog, svjetlozaštitno obrađenog drva.

Posljednjih godina intenzivno se radi na razvoju metoda poboljšanja svojstava i trajnosti drva i sustava prevlaka-drvo. Svojstva drva poput dimenzionalne stabilnosti, vodoodbojnosti, otpornosti prema biološkoj razgradnji te otpornosti prema ultraljubičastoj i vidljivoj svjetlosti, pa čak i mehanička svojstva drva mogu se poboljš ati modifikacijskim (toplinskim i kemijskim) postupcima. Nadalje, uvođenjem novih materijala za površinsku obradu s nanočesticama može se povećati vodoodbojnost, a dodatno i otpornost prema ultraljubičastom zračenju. Postupci toplinske modifikacije i acetilacija u inozemstvu se već komercijalno primjenjuju, dok se djelotvornost ostalih pokusnih postupaka, kao što je obrada površine nano premazima, tek treba potvrditi u praktičnoj primjeni. Zbog poboljšanih svojstava drvo ostaje konkurentan materijal u graditeljstvu, posebno za drvena pročelja, ograde, prozore i vrata, vrtni namještaj, ali i kao materijal za podove i namještaj u interijeru.

Die Fotodegradation von Holz ist im Wesentlichen ein Oberflaechenphaenomen und hat somit keinen direkten Einfluss auf die mechanischen Eigenschaften von Holzbauteilen. Stark beeintraechtigt werden hingegen die aesthetischen Eigenschaften und damit auch die Unterhaltsanforderungen. Der vorliegende Beitrag berichtet ueber aktuelle Untersuchungen der Empa gemeinsam mit der University of Zagreb zum Einfluss des Lichtspektrums und die Empfindlichkeit einzelner Holzarten gegenueber Fotodegradation.

Rad prikazuje usporedbu temeljnih odrednica kvalitete elemenata drvenih podnih obloga – masivnog parketa, kako ih definiraju trenutno važeće hrvatske i europske norme, kako bi se ocijenile potrebe naših proizvođača podnih elemenata u prilagodbi zahtjevima europskoga tržišta. Uspoređeni su zahtjevi fizikalnih, oblikovnih i estetskih odrednica kvalitete parketnih daščica prema HRN D.D5.020 (1980): Parket: Masivne parketne daščice, i DIN EN 13226 (2002): Masivne parketne daščice s utorom i perom. Analizom je procijenjeno koji od zahtjeva kvalitete su strožiji u europskoj nego u hrvatskoj normi, te kako im se treba udovoljiti. Razmatraju se prijedlozi tehnoloških poboljšanja kojima bi se lakše dosegle zahtijevane razine europske kvalitete.

Several surface treatments for transparent protection of exterior wood have been tested in natural and artificial weathering by measurements of contact angle, liquid water and vapour absorption, colour change and mechanical properties (« ; thin strip» ; method). Spruce wood was impregnated with HALS-containing primer and subsequently treated with UV-modified, nano-scaled hydrophobic emulsion, or by application of several transparent coatings. Hydrophobic properties (« ; pearling effect» ; and high contact angles) did not correlate well with water absorption, and the weathering resistance depended on the amount of UV additives and film thickness. Providing that sufficient depth of primer penetration and resistance to vapour transport are assured, transparent coating systems containing HALS, UV absorber and nano-based water repellent offer very promising enhancement of exterior wood service life.

Na hrvatskom tržištu nalazi se velik broj proizvoda drvene, plastične, metalne i kombinirane građevne stolarije (prozora i balkonskih vrata) različitih svojstava, kvalitete izrade i cijene. U radu se govori o užem izboru materijala za izradu prozorskih okvirnica kako bi se dobio pregled dostupnih materijala, njihovih svojstava i cijena. Prozori se danas komercijalno, industrijski izrađuju poglavito od drva, plastike, aluminija, čelika te od kombinacije drva i aluminija. Ovdje se razmatraju svojstva ove četiri vrste materijala s aspekta njihovih različitih mehaničkih i izolacijskih svojstava bitnih za izradu prozora, trajnosti, nabavne cijene, te mogućnosti i teškoća obnavljanja u životnom vijeku proizvoda. Drvo-aluminijski prozori predstavljaju tehnički najpovoljniji izbor za stambenu gradnju u Hrvatskoj.

An intensive research on the development of materials and methods of application which can improve the durability of wood and woodcoatings is being performed in recent years. Wood properties such as dimensional stability, water repellency, resistance to biological attack, UV- and visible light stability and even mechanical properties can be significantly improved by applying chemical and thermal treatments which are briefly presented in this work. Wood properties can be improved by heat treatment, acetylation, and plasma treatment or by application of nanocoatings. Heat treated and acetylated wood are commercially applied abroad, while possibilities for commercial usage of other modification methods need yet to be confirmed. Because the properties of modified wood are significantly improved, it can be successfully used for cladding and fencing, for noise reduction barriers, for joinery and furniture in exterior, and also for flooring and furniture in interior applications.

An ESEM (Environmental Scanning Electron Microscopy) technique has been applied to wood objects. ESEM investigations can be performed through several operational modes that offer various sets of environmental and imaging conditions. The comparison of ESEM micrographs with conventional SEM images revealed specific advantages and shortcomings of ESEM technique in studies on genuine and painted wood objects. Merits of the application of ESEM technique for wood are related to the absence of preparation artifacts, such as sputtering irregularities or defects due to shrinkage in vacuum drying. Great ESEM advantages over high-vacuum SEM, such as conduction of dynamic experiments within the chamber, are represented with a sequence of condensation, freezing and drying on a wood specimen. The wood imaging using ESEM proved inferior to that of SEM in terms of lower magnification, sharpness and contrast. However, the article offers guidance for assessment of influential operating parameters and their selection for the optimization of the ESEM work with wood. It may result in micrographs of sufficient resolution, definition and optical quality for study of wood structure on cellular and even intra-cellular level.