Performance of iron(II)-sulphate-treated Norway spruce and Siberian larch in laboratory and outdoor tests

Lesar, Boštjan (author), Humar, Miha (author)

Wood in outdoor applications is exposed to various environmental factors that cause weathering. Weathering is important, primarily from an aesthetic standpoint and predominantly in wooden claddings. However, not all parts of claddings are equally exposed to weathering. Sections exposed to UV radiation and moisture discolour faster than less exposed sections, such as wood under roof overhangs. Architects and owners seek a uniform appearance in buildings. To achieve fast and uniform greying, a surface treatment with iron(II) sulphate can be used. Such a treatment results in an appearance that is similar to that resulting from natural greying. However, iron compounds do not exert a biocidal effect; therefore, it is desirable to upgrade iron(II) sulphate aqueous solution with boric acid and quarterly ammonium compounds. To this end, spruce and larch samples were treated with varying concentrations of iron(II) sulphate and biocides. After treatment, the inherent durability, water performance and resistance dose (DRd) were determined according to the Meyer-Veltrup model. The samples were also exposed outdoor conditions. During exposure, colour changes and iron leaching were monitored. The results show that the addition of biocides does not affect the rate of colour change and the final colour, which is similar to natural greying after 36 weeks of outdoor exposure. The addition of biocides exerted a positive effect on the durability of treated wood, despite the low retention of preservative solutions. The water behaviour of the treated wood had little effect on the resistance dose, with a more considerable influence on inherent durability. The addition of biocides can increase the resistance dose up to 2.4 (Fe5B0.2Q0.2). On all spruce and larch samples treated with iron(II) sulphate and exposed to outdoor conditions, the colour change in the first week was roughly comparable to the final state. However, 40% of the iron had leached from the surface after only one week of exposure.

• Language: English
• Keywords: iron(II) sulphate, wood staining, quarterly ammonium compounds, wood decay, wetting ability, outdoor performance, Picea abies, Siberian larch
• Work type: Article
• Typology: 1.01 - Original Scientific Article
• Organization: BF - Biotechnical Faculty
• Publication status: Published
• Publication version: Version of Record
• Publication date: 15.09.2022
• Year: 2022
• Number of pages: 17 str.
• Numbering: Vol. 13, iss. 9
• PID: 20.500.12556/RUL-146683
• UDC: 630*8
• ISSN on article: 1999-4907
• DOI: 10.3390/f13091497
• COBISS.SI-ID: 121669123
• Publication date in RUL: 06.06.2023

Record is a part of a journal

• Title: Forests
• Shortened title: Forests
• Publisher: MDPI
• ISSN: 1999-4907
• COBISS.SI-ID: 3872166

Licences

• License: CC BY-NC 4.0, Creative Commons Attribution-NonCommercial 4.0 International
• Link: http://creativecommons.org/licenses/by-nc/4.0/
• Description: A creative commons license that bans commercial use, but the users don’t have to license their derivative works on the same terms.

Secondary language

• Language: Slovenian
• Keywords: železov(II) sulfat, razkroj lesa, odziv lesa na vodo, umetno staranje lesa, lastnosti lesa na prostem

Projects

• Funder: ARRS - Slovenian Research Agency
• Project number: P4-0015
• Name: Les in lignocelulozni kompoziti

• Funder: ARRS - Slovenian Research Agency
• Project number: 0481-09
• Name: IC za pripravo, staranje in terensko testiranje lesa ter lignoceluloznih materialov
• Acronym: OC LES PST