{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,6]],"date-time":"2026-10-06T00:03:38Z","timestamp":1791245018276,"version":"4.1.0"},"reference-count":44,"publisher":"MDPI AG","issue":"15","license":[{"start":{"date-parts":[[2025,8,1]],"date-time":"2025-08-01T00:00:00Z","timestamp":1754006400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"UEFISCDI Romania","award":["61PCE\/2022"],"award-info":[{"award-number":["61PCE\/2022"]}]},{"name":"UEFISCDI Romania","award":["PN-III-P4-PCE2021-0885"],"award-info":[{"award-number":["PN-III-P4-PCE2021-0885"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Polymers"],"abstract":"<jats:p>Spruce wood is a natural polymeric material, consisting of cellulose, lignin, hemicelluloses and other secondary components, which gives it a unique chemical footprint and architecture. Varnishes are used in musical instruments to protect the wood against humidity variations, wood being a hygroscopic material, but also to protect the wood from dirt. The varnishes used both to protect the wood from resonance and to ensure a special aesthetic appearance are either polymeric varnishes (nitrocellulose, oil-based) or volatile solvents (spirit). In this study, the color changes, the surface morphology and the chemical spectrum produced by three types of varnishes, applied in 5, 10 and 15 layers, on resonance spruce plates were analyzed. The results revealed significant changes in the color parameters: the lightness decreased by approximately 17% after the first layer, by 50% after 5 layers, by 65% after 10 layers and by 70% after 15 layers. The color parameters are most influenced by the anatomical quality of spruce wood (annual ring width and earlywood\/latewood ratio) in the case of oil-based varnishes and least influenced in the case of nitrocellulose varnishes. The chemical fingerprint was determined by FTIR spectrum analysis, which revealed that the most pronounced absorptions were the double band 2926\u20132858 cm\u22121, corresponding to aliphatic methylene and methyl groups (asymmetric and symmetrical C-H stretch), and the bands at 1724 cm\u22121 (oil-based varnish), 1722 cm\u22121 (nitrocellulose varnish) and 1708 cm\u22121 (spirit varnish), all assigned to non-conjugated carbonyl groups in either carboxylic acids, esters aldehydes or ketones. The novelty of the study lies in the comparative analysis of three types of varnishes used in the musical instrument industry, applied to samples of spruce resonance wood with different macroscopic characteristics in three different layer thicknesses.<\/jats:p>","DOI":"10.3390\/polym17152131","type":"journal-article","created":{"date-parts":[[2025,8,4]],"date-time":"2025-08-04T10:48:08Z","timestamp":1754304488000},"page":"2131","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":5,"title":["Comparisons of the Effects of Polymer and Alcohol Varnishes on Norway Spruce Wood Surface Modifications"],"prefix":"10.3390","volume":"17","author":[{"ORCID":"https:\/\/orcid.org\/0000-0001-6414-9427","authenticated-orcid":false,"given":"Mariana Domnica","family":"Stanciu","sequence":"first","affiliation":[{"name":"Department of Mechanical Engineering, Transilvania University of Bra\u0219ov, B-dul Eroilor 29, 500036 Brasov, Romania"},{"name":"Romanian Society of Rheology, Petru Poni Institute of Macromolecular Chemistry, Room 119, 41-A, Grigore Ghica Voda Alley, 700487 Iasi, Romania"},{"name":"Romanian Society of Theoretical and Applied Mechanics, 266 Pantelimon, 2 Sector, Office 4, 021652 Bucure\u0219ti, Romania"},{"name":"Romanian Society of Acoustics, 266 Pantelimon, 2 Sector, Office 4, 021652 Bucure\u0219ti, Romania"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-6118-5139","authenticated-orcid":false,"given":"Maria Cristina","family":"Timar","sequence":"additional","affiliation":[{"name":"Faculty of Furniture Design and Wood Engineering, Transilvania University of Brasov, 500036 Brasov, Romania"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Mircea","family":"Mihalcica","sequence":"additional","affiliation":[{"name":"Department of Mechanical Engineering, Transilvania University of Bra\u0219ov, B-dul Eroilor 29, 500036 Brasov, Romania"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-6271-8814","authenticated-orcid":false,"given":"Mihaela","family":"Cosnita","sequence":"additional","affiliation":[{"name":"Department of Product Design Mechatronics and Environment, Transilvania University of Brasov, 29 Eroilor, 500036 Brasov, Romania"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-0596-3562","authenticated-orcid":false,"given":"Florin","family":"Dinulic\u0103","sequence":"additional","affiliation":[{"name":"Faculty of Silviculture and Forest Engineering, Transilvania University of Brasov, 1 Sirul Bethoven, 500123 Brasov, Romania"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2025,8,1]]},"reference":[{"key":"ref_1","first-page":"163","article-title":"Basic chemical composition of wood as a parameter in raw material selection for biocomposite production","volume":"52","year":"2018","journal-title":"Cellul. Chem. Technol."},{"key":"ref_2","unstructured":"Srndovic, A.S. (2011). Interactions between Wood Polymers in Wood Cell Walls and Cellulose\/Hemicellulose Biocomposites. [Ph.D. Thesis, Chalmers University of Technology]."},{"key":"ref_3","unstructured":"Gh, P., and Popa, V.I. (1997). Chimia \u0219i Prelucrarea Chimic\u0103 a Lemnului, Publisher Lux Libris. (In Romanian)."},{"key":"ref_4","doi-asserted-by":"crossref","unstructured":"Stanciu, M.D., Teodorescu, H.D., Vlase, S., Mihalcica, M., Cosnit\u0103, M., and Savin, A. (2024). Multiscale assessment of artificial aging treatment of polysaccharides from tonewood species. Int. J. Biol. Macromol., 274.","DOI":"10.1016\/j.ijbiomac.2024.133310"},{"key":"ref_5","first-page":"3267","article-title":"Wood-Water Interactions as Affected by Chemical Constituents of Woods","volume":"20","author":"Sahin","year":"2008","journal-title":"Asian J. Chem."},{"key":"ref_6","doi-asserted-by":"crossref","unstructured":"Zhou, J., Wang, X., He, L., Wan, K., Guo, Y., Zhang, J., Miao, Y., and Liu, Z. (2024). The Changes of Acoustic Vibration Properties of Spruce Wood During the Multi-Layered Alcohol Varnish Coating Process. Forests, 15.","DOI":"10.3390\/f15122212"},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"420","DOI":"10.1016\/j.culher.2008.03.005","article-title":"Review on the characterisation of ancient stringed musical instruments varnishes and implementation of an analytical strategy","volume":"9","author":"Echard","year":"2008","journal-title":"J. Cult. Herit."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"31","DOI":"10.1016\/j.microc.2014.04.002","article-title":"Micro-analytical identification of the components of varnishes from South Italian historical musical instruments by PLM, ESEM\u2013EDX microFTIR, GC\u2013MS, and Py\u2013GC\u2013MS","volume":"116","author":"Caruso","year":"2014","journal-title":"Microchem. J."},{"key":"ref_9","first-page":"813","article-title":"Experimental characterization of oil-colophony varnishes: A preliminary study","volume":"7","author":"Weththimuni","year":"2016","journal-title":"Int. J. Conserv. Sci."},{"key":"ref_10","doi-asserted-by":"crossref","unstructured":"Odlyha, M., Lucejko, J.J., Lluveras-Tenorio, A., di Girolamo, F., Hudziak, S., Strange, A., Bridarolli, A., Bozec, L., and Colombini, M.P. (2022). Violin Varnishes: Microstructure and Nanomechanical Analysis. Molecules, 27.","DOI":"10.3390\/molecules27196378"},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"260","DOI":"10.1007\/s00339-016-9670-1","article-title":"Relationship of vibro-mechanical properties and microstructure of wood and varnish interface in string instruments","volume":"122","author":"Pflaum","year":"2016","journal-title":"Appl. Phys. A"},{"key":"ref_12","doi-asserted-by":"crossref","unstructured":"L\u00e4mmlein, S.L., Mannes, D., Van Damme, B., Schwarze, F.W.M.R., and Burgert, I. (2019). The influence of multi-layered varnishes on moisture protection and vibrational properties of violin wood. Sci. Rep., 9.","DOI":"10.1038\/s41598-019-54991-5"},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"76","DOI":"10.1186\/s40494-022-00718-1","article-title":"Chemical modification of wood induced by the traditional making procedures of bowed string musical instruments: The effect of alkaline treatments","volume":"10","author":"Albano","year":"2022","journal-title":"Herit. Sci."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"2300781","DOI":"10.1002\/admi.202300781","article-title":"Tunable Acoustic Properties Using Different Coating Systems on Resonance Spruce Wood","volume":"1","author":"Stanciu","year":"2024","journal-title":"Adv. Mater. Interfaces"},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"222","DOI":"10.1515\/hfsg.1995.49.3.222","article-title":"Dependence of Vibrational Properties of Wood on Varnishing during Its Drying Process in Violin Manufacturing","volume":"49","author":"Minato","year":"1995","journal-title":"Holzforschung"},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"397","DOI":"10.1250\/ast.14.397","article-title":"Effects of Varnishing on Acoustical Characteristics of Wood Used for Musical Instrument Soundboards","volume":"14","author":"Ono","year":"1993","journal-title":"J. Acoust. Soc. Jpn. E"},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"1175","DOI":"10.1121\/1.1911243","article-title":"Acoustical Effects of Violin Varnish","volume":"44","author":"Schelleng","year":"1968","journal-title":"J. Acoust. Soc. Am."},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"58","DOI":"10.1016\/j.talanta.2012.11.026","article-title":"CIEL\u204ea\u204eb\u204e color space predictive models for colorimetry devices\u2014Analysis of perfume quality","volume":"104","author":"Korifi","year":"2013","journal-title":"Talanta"},{"key":"ref_19","first-page":"262","article-title":"The effect of different wood varnishes on surface color properties of heat-treated wood materials","volume":"67","author":"Pelit","year":"2017","journal-title":"J. Fac. For. Istanb. Univ."},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"75","DOI":"10.2478\/aoa-2013-0009","article-title":"Modal parameters of two violins with different varnish layers and subjective evaluation of their sound quality","volume":"38","author":"Skrodzka","year":"2013","journal-title":"Arch. Acoust."},{"key":"ref_21","first-page":"45","article-title":"SHP Studies on the vibrational modal analysis of solid woods for making the violin\u2014Part 2. The effects of coating materials on the resonant frequency of European spruce and maple","volume":"11","author":"Chung","year":"2000","journal-title":"Korea Furnit. Soc."},{"key":"ref_22","first-page":"50","article-title":"Empirical Tools in Contemporary Violin Making: Part, I. Analysis of Design, Materials, Varnish, and Normal Modes","volume":"4","author":"Schleske","year":"2002","journal-title":"Catgut Acoust. Soc. J."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"27","DOI":"10.1250\/ast.22.27","article-title":"Effects of oriental lacquer (urushi) coating on the vibrational properties of wood used for the soundboards of musical instruments","volume":"22","author":"Obataya","year":"2001","journal-title":"Acoust. Sci. Technol."},{"key":"ref_24","first-page":"75","article-title":"Physical and Chemical Properties of Varnishes and Their Vibrational Consequences","volume":"43","author":"Simonnet","year":"2002","journal-title":"PACS Ref."},{"key":"ref_25","doi-asserted-by":"crossref","unstructured":"Stanciu, M.D., and Bucur, V. (2025). Violin Manufacturing Technology. Interdisciplinary Approach to the Violin, Springer.","DOI":"10.1007\/978-3-031-81734-2"},{"key":"ref_26","unstructured":"(1976). Half\u2013Stuffs for Musical Instruments with Strings and Bow (Standard No. STAS 10824-76). Romanian standard. (In Romanian)."},{"key":"ref_27","doi-asserted-by":"crossref","unstructured":"Dinulic\u0103, F., Stanciu, M.D., and Savin, A. (2021). Correlation between Anatomical Grading and Acoustic\u2013Elastic Properties of Resonant Spruce Wood Used for Musical Instruments. Forests, 12.","DOI":"10.3390\/f12081122"},{"key":"ref_28","doi-asserted-by":"crossref","unstructured":"Stanciu, M.D., Guiman, M.V., and N\u0103stac, S.M. (2025). New Challenges in Assessment of the Acoustic Properties of Coating Polymers. Polymers, 17.","DOI":"10.3390\/polym17101418"},{"key":"ref_29","unstructured":"L\u00e4mmlein, S.L. (2020). Violin Varnishes and Tonewood: Relationships of Vibromechanical and Moisture Sorption Properties. [Ph.D. Thesis, ETH Zurich]."},{"key":"ref_30","first-page":"100137","article-title":"Frequency dependent mechanical properties of violin varnishes and their im-pact on vibro-mechanical tonewood properties","volume":"9","author":"Schwarze","year":"2020","journal-title":"Results Mater."},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"51","DOI":"10.1007\/s00107-007-0201-9","article-title":"Wood surface discoloration due to simulated indoor sunlight exposure","volume":"66","author":"Olteanu","year":"2008","journal-title":"Holz Roh Werkst."},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"357","DOI":"10.1007\/s00226-016-0867-4","article-title":"An investigation of accelerated temperature-induced ageing of four wood species: Colour and FTIR","volume":"51","author":"Liu","year":"2017","journal-title":"Wood Sci. Technol."},{"key":"ref_33","doi-asserted-by":"crossref","unstructured":"Liu, X.Y., Timar, M.C., Varodi, A.M., Nedelcu, R., and Torc\u0103toru, M.J. (2022). Colour and Surface Chemistry Changes of Wood Surfaces Coated with Two Types of Waxes after Seven Years Exposure to Natural Light in Indoor Conditions. Coatings, 12.","DOI":"10.3390\/coatings12111689"},{"key":"ref_34","doi-asserted-by":"crossref","unstructured":"Gur\u0103u, L., Timar, M.C., Co\u0219ereanu, C., Cosnita, M., and Stanciu, M.D. (2023). Aging of Wood for Musical Instruments: Analysis of Changes in Color, Surface Morphology, Chemical, and Physical-Acoustical Properties during UV and Thermal Exposure. Polymers, 15.","DOI":"10.3390\/polym15071794"},{"key":"ref_35","doi-asserted-by":"crossref","unstructured":"Manzo, G., Tippner, J., and Zatloukal, P. (2021). Relationships between the Macrostructure Features and Acoustic Parameters of Resonance Spruce for Piano Soundboards. Appl. Sci., 11.","DOI":"10.3390\/app11041749"},{"key":"ref_36","unstructured":"(2007). STATISTICA, Version 8.0, StatSoft. Available online: http:\/\/www.statsoft.com."},{"key":"ref_37","doi-asserted-by":"crossref","first-page":"152528","DOI":"10.1016\/j.apsusc.2022.152528","article-title":"Wettability performance and physicochemical properties of UV exposed superhydrophobized birch wood","volume":"584","author":"Yin","year":"2022","journal-title":"Appl. Surf. Sci."},{"key":"ref_38","doi-asserted-by":"crossref","first-page":"226","DOI":"10.1016\/j.jsb.2013.03.003","article-title":"Hysteresis in swelling and in sorption of wood tissue","volume":"182","author":"Patera","year":"2013","journal-title":"J. Struct. Biol."},{"key":"ref_39","doi-asserted-by":"crossref","first-page":"6364","DOI":"10.1039\/D4TA07564A","article-title":"Laser-drilled functional wood materials show improved dimensional stability upon humidity changes\u2013a neutron imaging analysis","volume":"13","author":"Ding","year":"2025","journal-title":"J. Mater. Chem. A"},{"key":"ref_40","doi-asserted-by":"crossref","first-page":"131233","DOI":"10.1016\/j.colsurfa.2023.131233","article-title":"Synergistic effect of tung oil and heat treatment on surface characteristics and dimensional stability of wood","volume":"665","author":"He","year":"2023","journal-title":"Colloids Surf. A Physicochem. Eng. Asp."},{"key":"ref_41","doi-asserted-by":"crossref","first-page":"435","DOI":"10.1515\/hf-2019-0176","article-title":"An effective technique for constructing wood composite with superior dimensional stability","volume":"74","author":"Han","year":"2020","journal-title":"Holzforschung"},{"key":"ref_42","doi-asserted-by":"crossref","first-page":"551","DOI":"10.1016\/j.eurpolymj.2015.01.005","article-title":"Polymeric networks based on tung oil: Reaction and modification with green oil monomers","volume":"67","author":"Meiorin","year":"2015","journal-title":"Eur. Polym. J."},{"key":"ref_43","doi-asserted-by":"crossref","first-page":"113606","DOI":"10.1016\/j.indcrop.2021.113606","article-title":"Improvement of wood against UV weathering and decay by using plant origin substances: Tannin acid and tung oil","volume":"168","author":"Peng","year":"2021","journal-title":"Ind. Crops Prod."},{"key":"ref_44","doi-asserted-by":"crossref","unstructured":"Hang, J., Yan, X., and Li, J. (2024). A Review on the Effect of Wood Surface Modification on Paint Film Adhesion Properties. Coatings, 14.","DOI":"10.3390\/coatings14101313"}],"container-title":["Polymers"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2073-4360\/17\/15\/2131\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,9]],"date-time":"2025-10-09T18:21:38Z","timestamp":1760034098000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2073-4360\/17\/15\/2131"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2025,8,1]]},"references-count":44,"journal-issue":{"issue":"15","published-online":{"date-parts":[[2025,8]]}},"alternative-id":["polym17152131"],"URL":"https:\/\/doi.org\/10.3390\/polym17152131","relation":{},"ISSN":["2073-4360"],"issn-type":[{"value":"2073-4360","type":"electronic"}],"subject":[],"published":{"date-parts":[[2025,8,1]]}}}