Dimenzijska stabilnost podnih obloga od pregrijanog drva

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.Pregrijano se drvo uspješno primjenjuje za podne obloge zahvaljujući smanjenoj higroskopnosti, boljoj dimenzijskoj stabilnosti te ravnomjernoj promjeni boje u tamnije smeđe tonove. Cilj je ovog rada utvrditi higroskopski raspon i ravnotežni sadržaj vode pri sobnim uvjetima za dvije vrste pregrijanog drva za parket – za jasenovinu i bukovinu. Uzorci su tretirani pri dvije temperaturne razine – 190 i 210 °C, a svojstva uspoređena s nativnim drvom. Smanjenje dimenzijskih promjena izraženo je kao poboljšanje dimenzijske stabilnosti (engl. Anti Shrink Efficiency – ASE). Nadalje, od proba pregrijanog drva načinjene su parketne daščice, tretirane parketnim uljem i voskom, te testirane na vodoupojnost i paropropusnost. Koeficijenti utezanja pregrijanog drva nisu smanjeni u usporedbi s nativnim, ali je apsolutno smanjenje vodoupojnosti za 50% rezultiralo povećanjem dimenzijske stabilnosti za 60%. Površinska je obrada dodatno poboljšala higroskopna svojstva pregrijanog drva