Surface contamination from salts such as chlorides, sulphates and nitrates have been shown to lead to blistering of organic coatings, particularly in immersion conditions.
It is not sufficient, however to only measure the cleanliness of the substrate. In a multi-layer coating process, it is necessary to monitor and record the cleanliness of each layer prior to applying the next coating.
When using amine cured epoxy coatings, for example, in low ambient temperatures or in high humidity, a surface oiliness or exudate may cause inter-coating adhesion failure.
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