Conclusion
- Overall we can identify a bleaching effect over time with a trend for all species and treatments and an increase of the weathering equivalent of around 50 from 0 hours to the end of 800 hours.
- For the species is weathering trend generally steeper for the first 400 hours and is decreasing and flatten down after that.
- A comparable trend for all four tested wood species with a significant difference between some of the species.
- Almost no significant difference between the treatments and to the untreated control sample in general and also specific for each tested wood species, except Populus tremuloides
- Minimize bleaching effect through the treatments, which is not significant.
- High variance within the test samples.
1) Which wood species and coatings are useful to prevent the buildings from weathering?
2) Which coating is useful to make the buildings look original aged at their state of construction?
We can conclude that the species have a significant effect and Larix larcinia has the lowest weathering equivalent and Populus tremuloides the highest, but all species have the same weathering trend. So, for weathering on a darker level we should use Larix and on a lighter level we should use Populus or Picea.
Coatings have, especially after 800 hours, no significant effect on the weathering process. Over all species compared, THOMP and TWP are the only coatings which have an effect only at the beginning (time 0 hours) of the weathering process. Populus is the only tested wood species, where TWP as the only coating has a significant effect on the weathering.
Based on the second question there is no treatment or wood species which keeps the weathering process on one level, so make the buildings looking same aged all the time from the construction to the end.
The accelerated weathering is not comparable with a natural weathering. Natural weathering has a lot more, not simulatable, influencing factors like different UV-radiation spectrum, seasons etc. (Deflorian et al. 2007). It's still interesting if the results of the laboratory test have at least a comparable trend for the species and treatments or if the results are completely different.