Durability of Coatings

The loss of adhesion is produced by the influence of microclimate and the water film on the adherent surface which leads to swelling, blister formation and cracking [120]. 

The major difference between geographical sites is the intensity of the environmental factors. It is anticipated that intense sunshine will accelerate breakdown of coatings, but the level of humidity (usually expressed in terms of rainfall) will also have a significant effect. Thus it is usual for sites to be compared in terms of the climatic conditions [96, 116, 121-123]. 

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Podgorski, L. and Roux, M. (1999). Wood modification to improve the durability of coatings. Surface Coatings, 82(12), 590-596. 

S. H. Greenfeld, The Effects of Mineral Additives on the Durability of Coating Grade Roofing Asphalts, Building Materials and Structures Report 147, National Bureau of Standards, Washington, D.C., 1956. 

Nevertheless, the principal development goal is still to secure further improvements in the quality of paint systems and to prolong the durability of coating films. The longer the renewal of a coated surface can be delayed, the less the environment is polluted, and the smaller are the amounts of waste produced and of raw materials and energy consumed. 

All of the plastics, rubbers and composites described previously for their use in the automobile industry may or may not show any health hazard, depending on their preparation and contents. In this context, certainly the ones that are used in interiors are of the utmost importance and should be considered and examined more critically. On the other hand, the ones used in exteriors, should also be considered, not for their health hazard considerations, but mainly on different grounds (i.e., the loss of light stabilisers by migration from automotive finishes, which can significantly reduce the durability of coatings on plastic substrates [14]). 

Application techniques for coatings can be considered in various ways. The stability and durability of coating is essential. Coatings fliat have normal wear and tear requirements are... 

J. E. Pickett, Photostabilization of Plastics by Additives and Coatings, in Durability of Coatings and Plastics, R. Ryntz, ed., Hanser Publishers, 2001, pp. 73-98. 

TGSting. No test is available that reliably predicts the exterior durability of coatings, partly due to the wide variety of environments and application conditions (see Weathering). The limitations of accelerated tests, the need for data based on actual field experience, and methods of building a database are described in Reference 23. Use of reliability theory using statistical distribution functions of material, process, and exposure parameters for predicting exterior durability of automotive coatings has been recommended (46). Reference 55 reviews various test methods. 

Furthermore, there is considerable interest in potentiody-namic polarization techniques to rapidly tissess the durability of coated aluminum surfaces that have been painted or given various polymeric or einodic surface treatments [32,33]. Refer also to Chapter 56 in this section of the manual. 

While the issues discussed previously may seem academic, they are of great practical importance. This is particularly so with regard to the durability of coating effects under humid conditions, where the ability of the surface to adsorb water, which may hydrolyse surface bonds, is a key issue. 

Selection of an appropriate coating system is a prerequisite for the durability of coating. What are the major factors that would influence the choice There may be several factors, some of them are more important than others. Below is a list of such factors which deserve consideration ... 

The fast cure, high gloss, low shrinkage and high durability of coatings based on the anhydride/hydroxyl technology has been successfully developed in the automotive sector. 

Application techniques for coatings can be considered in various ways. The stability and durability of coating is essential. Coatings that have normal wear and tear requirements are mainly based on oils and aldehyde resins. Higher durability or stability can be achieved by the use of one of the following one- or two-component systems. One-component ... 

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