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    DETERMINATION OF PENDULUM HARDNESS (KONIG METHOD) VALUES AGAINST ARTIFICIAL WEATHERING IN WATER-BASED VARNISHES APPLIED TO SOME WOOD SPECIES AFTER HEAT TREATMENT (THERMOWOOD)
    (Inst Technol Drewna, 2021) Ayata, Umit; Cakicier, Nevzat
    Scots pine, beech, and oak are the most important tree species in the furniture sector in Turkey. In this study, the aim is to determine pendulum hardness (Konig method) values against artificial aging in water-based varnishes applied to some wood species after heat treatment. For this purpose, Scots pine (Pinus sylvestris L.), sessile oak (Quercus petreae L.), and Eastern beech (Fagus orientalis L.) wood samples were heat-treated at 190 degrees C for 2 h and at 212 degrees C for 1-2 h according to the ThermoWood method. Later, one- and two-component water-based varnishes (WBVOne-Comp. and WBVTwo-Comp.) were applied to the material surfaces in accordance with the manufacturer's recommendations for layer thickness for industrial applications. The materials were exposed to UV light using UV-A 340 nm fluorescent lamps for 144, 288, and 432 h in a QUV accelerated weathering tester. After these weathering periods, pendulum hardness values were determined. It was found that hardness values increased after weathering, and that WBVTwo-Comp. gave higher values than WBVOne-Comp..
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    Drewno. Prace naukowe. Doniesienia. Komunikaty Wood. Research papers. Reports. Announcements
    (Lukasiewicz Research Network, Poznan Inst Technology, 2026) Akter, Mete; Ulay, Goksel; Peker, Huseyin; Cakicier, Nevzat; Atilgan, Abdi; Ayata, Umit
    Pendulum hardness test is important for determining the mechanical durability and long-term performance of the film layer formed on the surface of wood thermally treated at high temperatures and coated with water-based varnish (WBV). In this study, the effect of artificial weathering conditions on the pendulum hardness (K & ouml;nig method) of ash (Fraxinus angustifolia Vahl.) wood samples varnished with polyurethane modified WBV was investigated. The samples were thermally treated under two conditions (190 degrees C for 1.5 h and 212 degrees C for 2 h) and compared with untreated control samples. The samples were exposed to artificial weathering conditions (for periods of 0, 168, 336 and 504 h). Pendulum hardness values were measured at the end of each weathering period. According to the results, increases in hardness values were observed in both heat-treated and untreated ash wood samples treated with varnish after weathering. In the varnished samples treated at 212 degrees C for 2 h, the post-weathering hardness increases were lower compared to the samples treated at 190 degrees C for 1.5 hand the control group. Additionally, analysis of variance for the pendulum hardness test, heat treatment, weathering time and their interaction were determined to be statistically significant. The significant increases in hardness values observed in the unweathered samples highlight the importance of the wood, varnish, and weathering process.
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    EFFECT OF ACCELERATED AGEING ON SOME SURFACE PROPERTIES OF UV-COATED HACKBERRY (Celtis australis L.) WOOD PARQUET
    (Inst Technol Drewna, 2021) Ayata, Umit; Esteves, Bruno; Gurleyen, Levent; Cakicier, Nevzat; Ferreira, Jose; Domingos, Idalina; Turk, Mutlu
    The importance of UV-curable coatings is currently increasing. In the parquet industry, where UV systems are applied, it is beneficial to investigate new tree species as potential raw materials. This study was carried out to determine the effect of accelerated ageing on some surface properties of hackberry (Celtis australis L.) wood treated with UV system parquet varnish. UV system parquet varnishes were applied to hackberry wood surfaces in three and five layers, according to the requirements of industrial applications. The varnished surfaces were then exposed to UV rays for 252 and 504 h using UVA-340 lamps in a QUV ageing device. Glossiness, colour parameters, pendulum hardness and adhesion strength (pull-off) (MPa) were determined for the coated samples before and after ageing, and the results for the aged and unaged test samples were compared. Analysis of variance showed that the results were significant for all tests. The results for all tests varied by ageing time.
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    Investigation of Use of Linden (Tilia tomentosa Moench.) Wood with UV System Varnish Application IN INDOOR Parquet Flooring
    (Inst Technol Drewna, 2023) Ayata, Umit; Esteves, Bruno; Domingos, Idalina; Ferreira, Jose; Efe, Fatih Tuncay; Turk, Mutlu; Cakicier, Nevzat
    Linden wood is used in the making of musical instruments, agricultural hand tools, and in the furniture sector. In this study, the changes in glossiness (parallel (//) and perpendicular (perpendicular to) to the fibers at 20o, 60o, and 85o), the pull -off adhesion test, color parameters (CIEL) and pendulum hardness (K & ouml;nig method) of two different UV curable varnishes applied to linden (Tilia tomentosa Moench.) according to industrial application techniques and exposed to artificial weathering were investigated. According to the research results, while L*, Delta H*, and ho decreased with increasing weathering time in both varnish layers, Delta C*, b*, Delta E*, a*, and C* rose. The pendulum hardness grew for Method B but dwindled for Method A. A decrease was found in the adhesion tests for both varnish methods after artificial weathering. The glossiness was generally reduced due to artificial weathering for all the angles and for both directions, with the exception of 85 degrees in Method A. The variance analysis and homogeneity groups showed that the changes in the adhesion, pendulum hardness, L*, a*, ho, C*, perpendicular and parallel to the fibers for 60o and 85o were found to be significantly different with artificial weathering for both methods.
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    The Effect of Weathering on Color and Glossiness Properties of Polyurethane-Modified Water-Based Varnish Layers Applied to Thermally Treated Ash Wood
    (North Carolina State Univ Dept Wood & Paper Sci, 2025) Ulay, Goksel; Akter, Mete; Cakicier, Nevzat; Peker, Huseyin; Ayata, Umit; Atilgan, Abdi; Ciftci, Seymen
    The effects of artificial weathering (168, 336, and 504 h) on the glossiness values and color parameters of varnished, polyurethane-modified ash wood were investigated. Samples included control samples without treatment and thermally treated samples under two different conditions (190 degrees C for 1.5 h and 212 degrees C for 2 h), all coated with a polyurethane-modified water-based varnish. In non-thermally treated and varnished samples, decreases in L* values were observed after weathering, while increases were noted in h(o), C*, b*, and glossiness at 60 degrees in both perpendicular and parallel directions to the fibers. After weathering, for samples thermally treated at 190 degrees C for 1.5 h and varnished, increases were observed in glossiness values at 20 degrees and 60 degrees in both directions, as well as in L*, b*, and h(o) values. Conversely, decreases were noted in a* and C* values. In samples thermally treated at 212 degrees C for 2 h and varnished, increases in a*, L*, h(o), b*, and C* values were detected after weathering, whereas decreases were observed in glossiness at all angles (20 degrees and 60 degrees) in both directions. The triangle E* values showed a decreasing trend in non-thermally treated varnished samples after weathering, while an increase was observed in samples thermally treated at 212 degrees C for 2 h and varnished.
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    Weathering effects on pendulum hardness, and pull-off adhesion testing of water-based varnish on thermally treated iroko wood
    (Taylor & Francis Ltd, 2026) Ulay, Goksel; Akter, Mete; Cakicier, Nevzat; Ayata, Umit
    This study evaluated the effects of different weathering durations (168, 336, and 504 h) on surface hardness and adhesion strength of both heat-treated (1.5 h at 190 degrees C and 2 h at 212 degrees C) and untreated iroko (Chlorophora excelsa) wood surfaces after application of water-based varnish (WBV). Pendulum hardness (s) and pull-off adhesion (MPa) tests were performed after weathering. According to the results, in the untreated control group, hardness increased from 30 s to 45 s after 504 h of weathering, showing a 48% increase. In the samples treated at 190 degrees C, hardness increased from 25 s to 41 s after 504 h, showing a 61% increase. The highest increase was observed in the samples treated at 212 degrees C. Here, the hardness increased from 23 s to 44 s, representing a 91% increase after 504 h of weathering. The highest initial surface adhesion strength (5.30 MPa) was obtained in the unheated samples; however, this value decreased significantly after weathering. Although the initial adhesion strength was lower in the heat-treated samples, those treated at 212 degrees C for 2 h exhibited more stable weathering performance. The results show that the acceleration of weathering and the application of heat significantly affect the effectiveness of the varnish coating.