New Strategies for Natural and Artificial Weathering Tests

摘要

1. There appears to be good agreement between the ranking obtained for each product in the various tests. 2. The prEN 927-6 seems to be the most selective test allowing a clearer attribution of the performance ranking to the coatings tested. 3. The wet adhesion test carried out at the end of the artificial weathering trial, seems to be a good way of testing the performance of a coating. It is interesting to note that the specimens stressed only by the artificial weathering test passed the usual visual checks (for chalking, cracking, flaking, loss of gloss). 4. The comparison of the results, deriving from the weathering tests and the UV permeability tests, does not show any particular direct relationship. These findings suggest that this parameter can have a significant influence on the durability of a coating but it is not sufficient to predict its performance. On the other hand it could be interesting to study the UV-permeability influence for a given formulation and its variability (due to stability and persistence of the UV-absorbers in the weathered film) over time. 5. These results seem to show a simple way for a relatively rapid evaluation of the clear coatings for wooden joinery by means of accelerated weathering tests in special conditions. We should however make two concluding observations regarding the project: 1. the analysis of a coating system has to take many factors into account in order to provide a global evaluation: application properties, aesthetic characteristics, blocking resistance, etc. Resistance to ageing is clearly one of the most important features and the opportunity to test this more rapidly is of very great interest; 2. the results obtained thus far, while very encouraging, cannot of course be regarded as conclusive; they will have to be confirmed and substantiated by further experimentation. We hope this work will also show that we were justified in proceeding in this manner, with the goal of making a contribution to the definition, understanding and diffusion of objective parameters for the evaluation of coatings for wooden doors and windows.