PEER-REVIEWED ARTICLE bioresources.com Leggate et al. (2021). “Darwin stringybark joining,” BioResources 16(1), 302-323. 302 The Influence of Mechanical Surface Preparation Method, Adhesive Type, and Curing Temperature on the Bonding of Darwin Stringybark William Leggate, a,b, * Robert L. McGavin, b,c Andrew Outhwaite, b Jack Dorries, b Rhianna Robinson, b Chandan Kumar, b Adam Faircloth, b and Mark Knackstedt a Darwin stringybark (Eucalyptus tetrodonta) is one of Northern Australia’s most important commercial forest resources. The wood exhibits desirable wood properties including high strength, natural durability, and visual appeal. The production of engineered wood products (EWPs) such as glulam from this resource represents a significant commercial opportunity for the timber industry in northern Australia. However, a major challenge to overcome is the achievement of satisfactory glue bond performance. This study evaluated the effects of different surface machining preparations, adhesive types, and curing temperatures on the bonding characteristics of Darwin stringybark. The pre-gluing surface machining method significantly influenced the timber wettability, roughness, permeability and tensile shear strength of adhesive bonds. Planing resulted in the lowest wettability, roughness, and permeability, while bonded planed samples produced the poorest tensile shear strength. Alternative surface machining methods including face milling and sanding post-planing were shown to significantly improve the timber wettability, roughness, and permeability, and also to increase the tensile shear strength of bonded samples. The resorcinol formaldehyde adhesive resulted in slightly improved tensile shear strength in most cases compared to the polyurethane adhesive. There was no significant improvement in tensile shear strength with the use of elevated temperature curing. Keywords: Wood surface machining; Wood wettability; Wood permeability; Wood adhesion; Wood roughness; Eucalyptus tetrodonta; Darwin stringybark Contact information: a: Research School of Physics and Engineering, The Australian National University, Canberra, ACT 0200, Australia; b: Queensland Department of Agriculture and Fisheries, Horticulture and Forestry Science, Salisbury Research Facility, 50 Evans Rd, Salisbury, Qld 4107, Australia; c: School of Civil Engineering, The University of Queensland, St. Lucia, Queensland, 4072, Australia; * Corresponding author: william.leggate@daf.qld.gov.au INTRODUCTION The demand for and use of engineered wood products (EWPs) continues to increase globally as consumers are increasingly favouring sustainable, low-embodied energy building products that are straighter, more stable, and uniform in size, exceed the performance capabilities of traditional timber products, are lighter in weight and have certified structural performance with reduced variability (Leggate 2018; Leggate et al. 2020a; Market Research Future 2020). The northern Australian timber industry is well placed to service a niche market for EWPs with performance properties that are superior to products manufactured from common commercial timber species on the international market. Australia’s native