Effects of coating ageing on the acoustic properties of Norway spruce (Picea abies)Straže, Aleš (Avtor) Žigon, Jure (Avtor) Pavlič, Matjaž (Avtor) spruce woodnitrocellulosepolyurethaneacoustic propertiesdampingcoating propertiescoating ageingNorway spruce (Picea abies L. Karst) wood is a preferred resonance material for musical instruments, but the surface coatings used to protect it also alter its acoustic behaviour. In this study, the effects of nitrocellulose and polyurethane coatings on spruce lamellas during an ageing period of 300 days were investigated. Gloss, hardness, impact resistance, resonance frequencies, vibration damping (tan δ) and acoustic conversion efficiency (ACE) were measured. Both coatings initially reduced the resonance frequencies and moduli of elasticity (E), while increasing the tan δ and reducing the ACE, with the nitrocellulose having a greater effect. Ageing led to greater hardness, lower tan δ and improved ACE, which can be attributed to the progressive curing of the coatings. The strong correlation between hardness and acoustic parameters suggests that mechanical surface properties may serve as predictors of acoustic effectiveness. Polyurethane maintained acoustic performance better than nitrocellulose, although impact resistance decreased with ageing. These results emphasize the importance of choosing coating systems that balance durability and long-term acoustic requirements in instrument making.20252025-11-04 08:22:41Članek v reviji175551sl