VARNISHING PERFORMANCE OF CRIMEAN JUNIPER (Juniperus excelsa M. Bieb.)

Abstract

The purpose of this study is to determine the varnish layer hardness and the varnish adhesion strength of the varnished Crimean juniper (Juniperus excelsa M. Bieb.) wood growing naturally in the Kastamonu region of Turkey. According to ASTM-D 3023-98, test samples were varnished with Caparol ™ Yachtlack brand UV-resistant polyurethane alkyd resin high gloss varnish and Cadence ™ brand water-based acrylic resin gloss varnish. The varnish adhesion strength test was carried out by using Shimadzu brand AG-IC 20/50 KN STD universal testing machine. The varnish layer hardness was measured by using König pendulum hardness tester in accordance with ASTM D4366-14. Also, Model CM2500d Konica® Minolta spectrophotometer was used for colour evaluation. The L*a*b* colour space was used for colour test. The adhesion strength of the polyurethane varnish and the water-based varnish were determined 2.81 MPa and 2.25 MPa respectively.  Surface hardness value for water-based varnishes and polyurethane varnishes were determined 71 and 25 oscillation respectively. Colour differences between unvarnished samples and water-based varnished samples were determined 9 units. Colour differences between unvarnished samples and polyurethane varnished samples were determined 16,96, while colour differences between water based  varnished samples and polyurethane varnished samples were determined 9,05 unit. Determining the performance of polyurethane and water-based varnish applications for the Crimean juniper wood will provide guidance in determining which type of varnish will be better for varnish applications of juniper wood. As a result, in the varnishing of the Crimean juniper wood, it is recommended that water-based acrylic varnish should be used when surface hardness is required, and polyurethane alkyd varnish should be used when better surface adhesion strength is desired.