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 16-02-2004

ConclusionsBlue stain testingBiological factorsWeathering and

assessmentIntro

Joris Van Acker – Imke De Windt – Jan Van den Bulcke

IntroductionIntroduction

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 16-02-2004

ConclusionsBlue stain testingBiological factorsWeathering and

assessmentIntro

Joris Van Acker – Imke De Windt – Jan Van den Bulcke

IntroductionIntroduction

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 16-02-2004

ConclusionsBlue stain testingBiological factorsWeathering and

assessmentIntro

Joris Van Acker – Imke De Windt – Jan Van den Bulcke

IntroductionIntroduction

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 16-02-2004

ConclusionsBlue stain testingBiological factorsWeathering and

assessmentIntro

Joris Van Acker – Imke De Windt – Jan Van den Bulcke

Weathering and assessmentWeathering 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 16-02-2004

ConclusionsBlue stain testingBiological factorsWeathering and

assessmentIntro

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 16-02-2004

ConclusionsBlue stain testingBiological factorsWeathering and

assessmentIntro

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 16-02-2004

ConclusionsBlue stain testingBiological factorsWeathering and

assessmentIntro

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 16-02-2004

ConclusionsBlue stain testingBiological factorsWeathering and

assessmentIntro

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 16-02-2004

ConclusionsBlue stain testingBiological factorsWeathering and

assessmentIntro

Joris Van Acker – Imke De Windt – Jan Van den Bulcke

Weathering and assessmentWeathering 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 16-02-2004

ConclusionsBlue stain testingBiological factorsWeathering and

assessmentIntro

Joris Van Acker – Imke De Windt – Jan Van den Bulcke

Weathering and assessmentWeathering 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 16-02-2004

ConclusionsBlue stain testingBiological factorsWeathering and

assessmentIntro

Joris Van Acker – Imke De Windt – Jan Van den Bulcke

Weathering and assessmentWeathering 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 16-02-2004

ConclusionsBlue stain testingBiological factorsWeathering and

assessmentIntro

Joris Van Acker – Imke De Windt – Jan Van den Bulcke

Biological factorsBiological 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 16-02-2004

ConclusionsBlue stain testingBiological factorsWeathering and

assessmentIntro

Joris Van Acker – Imke De Windt – Jan Van den Bulcke

Biological factorsBiological 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 16-02-2004

ConclusionsBlue stain testingBiological factorsWeathering and

assessmentIntro

Joris Van Acker – Imke De Windt – Jan Van den Bulcke

Biological factorsBiological factors

Standard tests: prEN927 3-5, 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 16-02-2004

ConclusionsBlue stain testingBiological factorsWeathering and

assessmentIntro

Joris Van Acker – Imke De Windt – Jan Van den Bulcke

Biological factorsBiological 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 16-02-2004

ConclusionsBlue stain testingBiological factorsWeathering and

assessmentIntro

Joris Van Acker – Imke De Windt – Jan Van den Bulcke

Blue stain testingBlue 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 16-02-2004

ConclusionsBlue stain testingBiological factorsWeathering and

assessmentIntro

Joris Van Acker – Imke De Windt – Jan Van den Bulcke

Blue stain testingBlue 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 16-02-2004

ConclusionsBlue stain testingBiological factorsWeathering and

assessmentIntro

Joris Van Acker – Imke De Windt – Jan Van den Bulcke

Blue stain testingBlue 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 16-02-2004

ConclusionsBlue stain testingBiological factorsWeathering and

assessmentIntro

Joris Van Acker – Imke De Windt – Jan Van den Bulcke

ConclusionsConclusions

- 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...