## 4 Conclusions  
It was possible to achieve the same color using different processes of thermal modification at 160 \({}^{\circ}\)C in a closed system and 210 \({}^{\circ}\)C in an open system.  
Thermal modification reduced wood lightness (L*), red-green chromaticity coordinate (a*), and yellow-blue chromaticity coordinate (b*). L* and a* had the biggest and smallest variations, respectively. The color of thermally modified wood was significantly changed, even at the mildest condition tested: 185 \({}^{\circ}\)C, open system, and 0.33% corrected mass loss.  
Even at a lower temperature (160 \({}^{\circ}\)C), the corrected mass loss was higher (18.47%) in the closed system than in the open system (185 \({}^{\circ}\)C: 0.33% and 210 \({}^{\circ}\)C: 2.44%), indicating that the type of process had more influence on mass loss than the temperature. This resulted in different effects on the chemical composition, with a higher effect at 160 \({}^{\circ}\)C in the closed system on the hemicellulose content (reduced) and the extractive content (increased for all solvents). The hemicellulose were the most susceptible components of the cell wall to thermal modification.  
There was no difference in the chemical composition of untreated wood and thermally modified wood in an open system at 185 \({}^{\circ}\)C, except for the extractive content in dichloromethane, which was reduced in the latter.  
We suggest that more studies are needed to clarify the effect of extractive content (in different solvents) on the color of thermally modified wood, mainly in cases where different processes are used. These studies could include the identification of the different extractives using chromatographic techniques.  
**Author Contributions:** Conceptualization, D.C.B., P.H.G.d.C., H.F.N. and J.B.P.; Methodology, D.C.B., F.d.S.G., M.d.S.R., A.C.O.R. and L.d.C.D.; Software, P.H.d.S.S., A.C.O.R. and J.P.S.M.; Validation, D.C.B., P.H.G.d.C., H.F.N. and J.B.P.; Formal analysis, F.d.S.G., J.S.d.S.F. and P.H.d.S.S.; Investigation, F.d.S.G., M.d.S.R., A.C.O.R. and L.d.C.D.; Data curation, D.C.B., F.d.S.G. and P.H.d.S.S.; Writing--original draft preparation, F.d.S.G., P.H.d.S.S. and J.S.d.S.F.; Writing--review and editing, D.C.B., J.S.d.S.F., P.H.d.S.S., P.H.G.d.C., H.F.N. and J.B.P.; Supervision, D.C.B., P.H.G.d.C., H.F.N. and J.B.P.; Project administration, D.C.B.; Funding acquisition, D.C.B. All authors have read and agreed to the published version of the manuscript.  
**Funding:** This research was financed in part by the Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior, Brasil (CAPES), Finance Code 001, scholarship to F.d. S.G.; the National Council for Scientific and Technological Development, CNPq, grant number 422637/2018-1; and CAPES/Fundacao de Amparo a Pesquisa e Inovacao do Espirito Santo (FAPES), through the \"Programa de Desenvolvimento da Pos-graduacao\" (PDPG), Consolidacao dos Programas de Pos-graduacao da Area de Ciencias Aggrarias do Estado do Espirito Santo, Ciencias Florestais, call FAPES/CNPq N\({}^{\circ}\) 23/2018--PRONEM, process number 2021-FDGS5 and grant agreement 131/2021.  
**Institutional Review Board Statement:** Not applicable.  
**Infrared Consent Statement:** Not applicable.  
**Data Availability Statement:** The data presented in this study are available on request from the corresponding author. The data are not publicly available because they are part of a project funded by a Brazilian Government funding agency. Therefore, before sharing the data, the authors would need prior authorization.  
**Acknowledgments:** The authors express their gratitude to the company TWBrazil for donating the material, thermally modifying it in closed system, and shipping it to the execution institution.  
**Conflicts of Interest:** The authors declare no conflict of interest.