Difficulties to combine biological degradation factors with artificial weathering Focussing on how to measure and evaluate

Difficulties to combine biological degradation factors with artificial weathering - focussing on how to measure and evaluate COST E18 Symposium Copenhagen Intro Weathering and assessment Biological factorsBlue stain testingConclusions Joris Van Acker – Imke De Windt – Jan Van den Bulcke Introduction Standardised methods: European: EN 927 International: ISO  Problems: critical values performance assessment

Difficulties to combine biological degradation factors with artificial weathering - focussing on how to measure and evaluate COST E18 Symposium Copenhagen Intro Weathering and assessment Biological factorsBlue stain testingConclusions Joris Van Acker – Imke De Windt – Jan Van den Bulcke Introduction Natural weathering, CEN/TC139/WG2: accelerated natural exposure Climatic Index + mimicry - transfer of biological degradation patterns Artificial ageing: UVS equipment (UV-CON, QUV with spray option) Wheater-O-meter (WOM) + fast - physico-mechanical

Difficulties to combine biological degradation factors with artificial weathering - focussing on how to measure and evaluate COST E18 Symposium Copenhagen Intro Weathering and assessment Biological factorsBlue stain testingConclusions Joris Van Acker – Imke De Windt – Jan Van den Bulcke Introduction Solution: combined or sequential testing of physico-mechanical and biological ageing short-term critical levels special focus on biological performance

Difficulties to combine biological degradation factors with artificial weathering - focussing on how to measure and evaluate COST E18 Symposium Copenhagen Intro Weathering and assessment Biological factorsBlue stain testingConclusions Joris Van Acker – Imke De Windt – Jan Van den Bulcke Weathering and assessment Natural weathering: - mimicry disadvantages: weather sample variability - harmonisation of specimens and exposition disadvantages: macro- and microclimate

Difficulties to combine biological degradation factors with artificial weathering - focussing on how to measure and evaluate COST E18 Symposium Copenhagen Intro Weathering and assessment Biological factorsBlue stain testingConclusions Joris Van Acker – Imke De Windt – Jan Van den Bulcke

Difficulties to combine biological degradation factors with artificial weathering - focussing on how to measure and evaluate COST E18 Symposium Copenhagen Intro Weathering and assessment Biological factorsBlue stain testingConclusions Joris Van Acker – Imke De Windt – Jan Van den Bulcke

Difficulties to combine biological degradation factors with artificial weathering - focussing on how to measure and evaluate COST E18 Symposium Copenhagen Intro Weathering and assessment Biological factorsBlue stain testingConclusions Joris Van Acker – Imke De Windt – Jan Van den Bulcke

Difficulties to combine biological degradation factors with artificial weathering - focussing on how to measure and evaluate COST E18 Symposium Copenhagen Intro Weathering and assessment Biological factorsBlue stain testingConclusions Joris Van Acker – Imke De Windt – Jan Van den Bulcke

Difficulties to combine biological degradation factors with artificial weathering - focussing on how to measure and evaluate COST E18 Symposium Copenhagen Intro Weathering and assessment Biological factorsBlue stain testingConclusions Joris Van Acker – Imke De Windt – Jan Van den Bulcke Weathering and assessment Artificial weathering: higher reproducibility more confidence in:  machines  ageing cycles less time consuming better control

dark & dry cold period water spray UV light

Difficulties to combine biological degradation factors with artificial weathering - focussing on how to measure and evaluate COST E18 Symposium Copenhagen Intro Weathering and assessment Biological factorsBlue stain testingConclusions Joris Van Acker – Imke De Windt – Jan Van den Bulcke Weathering and assessment Assessment parameters: chalking flaking blistering cracking adhesion Not necessary critical for all coatings degradation phenomena on wood ‘missing’: biological erosion additional

Difficulties to combine biological degradation factors with artificial weathering - focussing on how to measure and evaluate COST E18 Symposium Copenhagen Intro Weathering and assessment Biological factorsBlue stain testingConclusions Joris Van Acker – Imke De Windt – Jan Van den Bulcke Weathering and assessment Needs for methodology: optimisation prioriy of parameters substrate:  hardwood  softwood  porosity, vessel grouping  dimensional stability  extractives sample size: boards  window frame corners

Difficulties to combine biological degradation factors with artificial weathering - focussing on how to measure and evaluate COST E18 Symposium Copenhagen Intro Weathering and assessment Biological factorsBlue stain testingConclusions Joris Van Acker – Imke De Windt – Jan Van den Bulcke Biological factors Biological factors can be essential part of paint degradation:

Difficulties to combine biological degradation factors with artificial weathering - focussing on how to measure and evaluate COST E18 Symposium Copenhagen Intro Weathering and assessment Biological factorsBlue stain testingConclusions Joris Van Acker – Imke De Windt – Jan Van den Bulcke Biological factors Biological factors can be essential part of paint degradation:

Difficulties to combine biological degradation factors with artificial weathering - focussing on how to measure and evaluate COST E18 Symposium Copenhagen Intro Weathering and assessment Biological factorsBlue stain testingConclusions Joris Van Acker – Imke De Windt – Jan Van den Bulcke Biological factors Standard tests: prEN , EN152  artificial weathering Alternative tests: susceptibility fungal growth on, through, in the coating and the substrate impact analysis

Difficulties to combine biological degradation factors with artificial weathering - focussing on how to measure and evaluate COST E18 Symposium Copenhagen Intro Weathering and assessment Biological factorsBlue stain testingConclusions Joris Van Acker – Imke De Windt – Jan Van den Bulcke Biological factors Additional parameters: film thickness water and water vapour permeability porosity surface roughness

Difficulties to combine biological degradation factors with artificial weathering - focussing on how to measure and evaluate COST E18 Symposium Copenhagen Intro Weathering and assessment Biological factorsBlue stain testingConclusions Joris Van Acker – Imke De Windt – Jan Van den Bulcke Blue stain testing Blue stain testing basics EN152: + WOM coating not on the vermiculite medium (contact with uncoated side) Aureobasidium pullullans and Sclerophoma pithyophila evaluation of surface blue staining and zone free of blue stain

Difficulties to combine biological degradation factors with artificial weathering - focussing on how to measure and evaluate COST E18 Symposium Copenhagen Intro Weathering and assessment Biological factorsBlue stain testingConclusions Joris Van Acker – Imke De Windt – Jan Van den Bulcke Blue stain testing Reversed method: coating on the vermiculite medium, other sides sealed Aureobasidium pullullans and Sclerophoma pithyophila evaluation of surface blue staining and interior presence of blue stain

Difficulties to combine biological degradation factors with artificial weathering - focussing on how to measure and evaluate COST E18 Symposium Copenhagen Intro Weathering and assessment Biological factorsBlue stain testingConclusions Joris Van Acker – Imke De Windt – Jan Van den Bulcke Blue stain testing Internal presence of blue stain in service: not just a blue free zone

Difficulties to combine biological degradation factors with artificial weathering - focussing on how to measure and evaluate COST E18 Symposium Copenhagen Intro Weathering and assessment Biological factorsBlue stain testingConclusions Joris Van Acker – Imke De Windt – Jan Van den Bulcke Conclusions - Modern coatings: low VOC + low biocidal content - Increased impact of biological factors - Yearly changes in impact of biological coating degradation - Reproducible testing: artificial ageing + laboratory test method - Artificial ageing should be specific for wood - Wood coatings mainly fail due to moisture impact (swelling / shrinkage) - Blue stain in service testing of coatings differs testing fungicidal impact - Modern water- borne wood coatings should be able to resist biological factors... by means non-biocidal components or parameters...