Vol.67: e24231048, 2024 https://doi.org/10.1590/1678-4324-2024231048 ISSN 1678-4324 Online Edition Brazilian Archives of Biology and Technology. Vol.67: e24231048, 2024 www.scielo.br/babt Article - Engineering, Technology and Techniques. Performance of Spray-Dried Nanofibrillated Cellulose as Wood Varnish Reinforcement in Outdoor Environment Ana Paula Namikata da Fonte 1 https://orcid.org/0000-0003-2932-3172 Bruna Mulinari Cabral 1 https://orcid.org/0000-0002-8879-2537 Tarcila Rosa da Silva Lins 1 https://orcid.org/0000-0002-5809-6741 Mayara Elita Carneiro 1 https://orcid.org/0000-0001-7676-5868 Elaine Cristina Lengowski 2 https://orcid.org/0000-0002-7336-7626 Eraldo Antonio Bonfatti Júnior 1 * https://orcid.org/0000-0002-2730-7681 Umberto Klock 1 https://orcid.org/0000-0003-3946-3320 Alan Sulato de Andrade 1 https://orcid.org/0000-0003-1574-9623 Dimas Agostinho da Silva 1 https://orcid.org/0000-0002-5433-1927 1 Universidade Federal do Paraná, Setor de Ciências Agrárias, Departamento de Engenharia e Tecnologia Florestal, Curitiba, Paraná, Brasil; 2 Universidade Federal do Mato Grosso, Faculdade de Engenharia Florestal, Departamento de Engenharia Florestal, Cuiabá, Mato Grosso, Brasil. Editor-in-Chief: Alexandre Rasi Aoki Associate Editor: Alexandre Rasi Aoki Received: 16-Oct-2023; Accepted: 12-Jan-2024 *Correspondence: bonfattieraldo@gmail.com; Tel.: +55-41-998302630 (E.A.B.J.). Abstract: The outdoor use of wood can be improved by coating the wood surface with varnish to reduce the effects of natural weathering. However, some varnishes quickly lose their ability to protect wood, and nanoscale additives have been used to mitigate this negative effect, preferably renewable and biodegradable. Therefore, the objective of this study was to evaluate the performance of varnishes reinforced with spray- dried nanofibrillated cellulose (NFC) in a natural weathering test. For this purpose, two varnishes, waterborne and non-waterborne, with 0, 5, and 10% (w/w) NFC addition were applied to Pinus taeda tangential wood samples, which were exposed to natural weathering for half a year, during the period from January to June 2019, in Curitiba, PR, Brazil. Adherence and impact resistance tests were performed to evaluate the surface properties of the varnishes, and the effect of natural weathering on the wood surface was evaluated using quantitative colorimetric analyses (CIELab System). The varnishes did not perform well in the adhesion and HIGHLIGHTS • The addition of nanocellulose showed no effects on the varnish properties. • All changes in color caused by natural weathering were noticeable. • Exposure to natural weathering caused wood color to become gray. • Addition of 5% nanocellulose reduced the variation in wood color.