Performance of Exterior Wood Coatings in Temperate Climates

Davis, K. J.; Leavengood, Scott; Morrell, Jeffrey J.

doi:10.3390/coatings11030325

Cited by 10 publications

(15 citation statements)

References 22 publications

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“…The selection of the most appropriate coating, in terms of composition, features and performance, as well as the most suitable application techniques depends on many factors, such as the nature and characteristics of the substrate, the exposure site and climate, specific requirements. Once applied to the substrate to protect, it is essential to analyze the durability of the coating, either by natural exposure and accelerated aging, to assess after how long its performance decays, and therefore it must be replaced [39][40][41].…”

Section: Comparison Between On Field Durability Tests With Accelerated Proceduresmentioning

confidence: 99%

Can Accelerated Aging Procedures Predict the Long Term Behavior of Polymers Exposed to Different Environments?

Frigione

Rodríguez-Prieto

2021

Polymers

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During their useful life, polymers are subject to degradation processes due to exposure to specific environmental conditions over long times. These processes generally lead to changes, almost always irreversible, of properties and performances of polymers, changes which would be useful to be able to predict in advance. To meet this need, numerous investigations have been focused on the possibility to predict the long-term performance of polymers, if exposed to specific environments, by the so called “accelerated aging” tests. In such procedures, the long-term behavior of polymeric materials is typically predicted by subjecting them to cycles of radiations, temperatures, vapor condensation, and other external agents, at levels well above those found in true conditions in order to accelerate the degradation of polymers: this can produce effects that substantially deviate from those observable under natural exposure. Even following the standard codes, different environmental parameters are often used in the diverse studies, making it difficult to compare different investigations. The correlation of results from accelerated procedures with data collected after natural exposure is still a debated matter. Furthermore, since the environmental conditions are a function of the season and the geographical position, and are also characteristic of the type of exposure area, the environmental parameters to be used in accelerated aging tests should also consider these variables. These and other issues concerning accelerated aging tests applied to polymers are analyzed in the present work. However, bearing in mind the limitations of these practices, they can find useful applications for rating the durability of polymeric materials.

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Section: Comparison Between On Field Durability Tests With Accelerated Proceduresmentioning

confidence: 99%

Can Accelerated Aging Procedures Predict the Long Term Behavior of Polymers Exposed to Different Environments?

Frigione

Rodríguez-Prieto

2021

Polymers

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“…It was found that RGB and HSL paraments measured on uncoated acetylated wood samples revealed noticeable alterations after just one month of exposure. Similar research on the natural weathering performance of five wood species coated with 12 diverse formulations was conducted in Oregon (US) for a period of 18 months [38]. It was reported that most of the tested coatings lost their protective effects within the first year of exposure due to combinations of diverse biological and abiotic factors.…”

Section: Discussionmentioning

confidence: 75%

Hybrid Approach for Wood Modification: Characterization and Evaluation of Weathering Resistance of Coatings on Acetylated Wood

Sandak

Földvári-Nagy²,

Poohphajai

et al. 2021

Coatings

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Wood, as a biological material, is sensitive to environmental conditions and microorganisms; therefore, wood products require protective measures to extend their service life in outdoor applications. Several modification processes are available for the improvement of wood properties, including commercially available solutions. Among the chemical treatments, acetylation by acetic anhydride is one of the most effective methods to induce chemical changes in the constitutive polymers at the cellular wall level. Acetylation reduces wood shrinkage-swelling, increases its durability against biotic agents, improves UV resistance and reduces surface erosion. However, even if the expected service life for external cladding of acetylated wood is estimated to be 60 years, the aesthetics change rapidly during the first years of exposure. Hybrid, or fusion, modification includes processes where the positive effect of a single treatment can be multiplied by merging with additional follow-up modifications. This report presents results of the performance tests of wood samples that, besides the modification by means of acetylation, were additionally protected with seven commercially available coatings. Natural weathering was conducted in Northern Italy for 15 months. Samples were characterized with numerous instruments by measuring samples collected from the stand every three months. Superior performance was observed on samples that merged both treatments. It is due to the combined effect of the wood acetylation and surface coating. Limited shrinkage/swelling of the bulk substrate due to chemical treatment substantially reduced stresses of the coating film. Hybrid process, compared to sole acetylation of wood, assured superior visual performance of the wood surface by preserving its original appearance.

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“…The samples were prepared as previously described by Davis et al, [11]. Briefly, kiln-dried lumber was cut into clear, knot-free coupons 19 mm thick, 75 mm wide, and 150 mm long.…”

Section: Coatings and Wood Speciesmentioning

confidence: 99%

“…A total of 36 coupons were produced for each species and allocated into 6 treatment groups, each containing 6 samples for both studies [11]; however, a subset of wood species (presented above) and coatings was selected for comparison between the sites. The coatings (Table 1) selected represent three of the major coating types that are commercially available (i.e., film-forming, penetrating oil, and water-based).…”

Section: Coatings and Wood Speciesmentioning

confidence: 99%

“…Although related, this study focused on the comparison of coating performance in two dramatically different climates. This study used methods developed by Davis et al, [11], with a relatively inexpensive flatbed scanner and standard image analysis procedures to measure color change on 2 species treated with 3 coatings over 25 months of natural weathering in the semi-arid climate of central Oregon (Davis et al, [11]).…”

Section: Introductionmentioning

confidence: 99%

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Effects of Climate on Exterior Wood Coating Performance: A Comparison of Three Industrial Coatings in a Warm-Summer Mediterranean and a Semi-Arid Climate in Oregon, USA

Davis¹,

Leavengood

Morrell

2022

Coatings

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Wood exposed in exterior applications degrades and changes color due to weathering and fungal growth. Wood coatings can reduce the effects of weathering by reducing the damaging effects of ultraviolet light, reducing water absorption, and slowing fungal growth on the surface. Coating performance depends on the blend of resins, oils, and pigments and varies considerably among different wood species and conditions. Specific information describing expected service for different wood species and exposure conditions is not commonly available; certain combinations may work well in one climate or on one timber species, but underperform elsewhere. This study compared the performance of three industrial wood coatings on two wood species for two temperate climates under natural weathering conditions. Most of the coatings/species combinations lost their protective properties within 12 to 15 months; however, fungal growth was more prevalent at the wetter site than at the drier site for several combinations. Film-forming coatings often peeled and cracked, while penetrating coatings weathered and changed color relatively uniformly during the study. While no coating was completely effective, the results illustrate the benefits of using coatings that promote the development of natural, uniform-patinaed wood surfaces. The findings also guide coating maintenance programs for mass timber structures exposed to natural weathering conditions.

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Performance of Exterior Wood Coatings in Temperate Climates

Cited by 10 publications

References 22 publications

Can Accelerated Aging Procedures Predict the Long Term Behavior of Polymers Exposed to Different Environments?

Can Accelerated Aging Procedures Predict the Long Term Behavior of Polymers Exposed to Different Environments?

Hybrid Approach for Wood Modification: Characterization and Evaluation of Weathering Resistance of Coatings on Acetylated Wood

Effects of Climate on Exterior Wood Coating Performance: A Comparison of Three Industrial Coatings in a Warm-Summer Mediterranean and a Semi-Arid Climate in Oregon, USA

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