Towards durable outdoor wooden sculptures : a case study from ukanc (slovenia)

Kržišnik, Davor (author), Vuga, Martina (author), Kavkler, Katja (author), Božič, Teja (author), Vinder, Jasna (author), Humar, Miha (author)

Outdoor wooden sculptures are increasingly commissioned as part of cultural heritage and placemaking, yet their long-term performance is compromised by moisture ingress, UV-induced photodegradation, biological attack, and inadequate installation details. Building on a recent in depth case study of a three-metre oak totem sculpture installed in Ukanc (Bohinj, Slovenia), we present a practice-oriented conservation protocol that integrates diagnostics, biotic risk mitigation, surface protection, structural retrofitting, and maintenance. Diagnostics combined a condition survey, resistograph profiling, and laboratory analyses on oak samples, namely FTIR-DRIFT to assess consolidant penetration, CIELAB colourimetry to quantify visual change, and compression testing to evaluate mechanical response. Consolidants (melamine resin in three concentrations, Paraloid B72, Sokrat 2804, and a two-component epoxy) were applied by brushing or one-hour immersion. Results showed negligible dimensional changes and no significant penetration of consolidants into the core; melamine resins lightened the surface, Paraloid B72 and Sokrat 2804 caused minimal colour change, while epoxies darkened and increased gloss; compression strength did not improve, consistent with the poor penetration observed by FTIR-DRIFT. For rapid elimination of fungi and insects, we recommend microwave sterilisation (approximately 70 °C for 5-15 minutes for fungi; approximately 60 °C for 10 minutes for insects), followed by a colourless water-based biocide (e.g., borate- and QAC-containing Silvanol) and a heat-cured hydrophobic wax (Silvacera) to reduce water uptake and slow biocide leaching. Structural stabilisation is achieved by hollowing the degraded base and inserting a laminated oak block (grain-aligned), enabling a robust mounting system (stainless-steel sleeve, ventilated gap, drainage features, and protective metal caps) that promotes drying and prevents water entrapment. To reduce moisture risk, the installation is designed to meet EN 335 Class 2 conditions (raised from the ground, protected from direct wetting) and is complemented by a simple, auditable maintenance plan (biannual inspection and documentation; annual dry cleaning and biocide reapplication; hydrophobisation every one to two years). The protocol bridges the gap between diagnosis and execution for outdoor sculptures and can be adapted to other heritage objects exposed to similar hazards, aligning good conservation practice with modern performance-based wood protection.

• Language: English
• Keywords: outdoor wooden sculpture, fungal decay, microwave sterilisation, biocide, hydrophobic wax, maintenance
• Work type: Other
• Typology: 1.08 - Published Scientific Conference Contribution
• Organization: BF - Biotechnical Faculty; ALUO - Academy of Fine Arts and Design
• Publication status: Published
• Publication version: Author Accepted Manuscript
• Year: 2026
• Number of pages: 41
• PID: 20.500.12556/RUL-183295
• UDC: 630*8
• COBISS.SI-ID: 280922627
• Publication date in RUL: 10.06.2026

Record is a part of a monograph

• Title: IRG documents database and compendium
• Place of publishing: Stockholm
• Publisher: IRG Secretariat
• Year: 2004
• COBISS.SI-ID: 82640387

Secondary language

• Language: Slovenian
• Keywords: lesene strukture na prostem, glive razkrojevalke lesa, mikrovalovna sterilizacija, biocidi, hidrofobni vosek, vzdrževanje