The performance of any coating is directly dependent upon the correct and thorough preparation of the surface prior to painting. This is why a NACE or ICorr coating inspector is vital to ensure your painting contractor operates within the coating specification given. It is even more so of a requirement when the area to be prepared and painted is at a height, out of reach of easy maintenance. The most expensive and technologically advanced coatings systems will fail prematurely if the surface preparation is incorrect or incomplete.
The moisture content of the air influences painting operations and is indicated by relative humidity at a particular temperature. Relative humidity is important during paint application since the amount of moisture in the air and temperature of the metallic steel surface may lead to condensation forming on the substrate which inevitably will lead to adhesion problems with most coatings. Industrial paints are normally sensitive to humidity during their curing, for instance, the surface of amine cured epoxy based coatings will be affected by high humidity conditions, and although the coating layer itself is undamaged after curing, it will be susceptible to cohesion problems should this be over-coated. Such coating can develop a surface oiliness or whitish spots often referred to as amine-blush, sweating or bloom, needing to be rectified usually under the correct supervisison of a coating inspector.
While other such paints like some zinc silicate coatings will not cure completely under low humidity conditions. The conditions applicable to various industrial coatings should be provided by the paint manufacturer and can usually be found in technical data sheets for the specific painting product being applied.
Thats why at Dangle we highly recommend that you let us take the hassle and costly re-work out of painting contracts using our highly skilled and knowledgeable rope access NACE coating inspectors and ICORR inspection services personnel.
From the preparation of the surface to be coated, through to climatic condition monitoring to the dry film thickness evaluation post cure, visual assessment and non destructive gauge-based testing we will ensure an adequate process control is in place.
For steel surface preparation, the removal of rust and other contamination and the creation of a surface profile is required to enhance the adhesion of the applied coatings. We can provide you with a range of services for rust removal and a simple test for dust on blast-cleaned surfaces. In order to determine the level of soluble salt contamination of a blast cleaned surface, a range of salt contamination methods are available including the Bresle Patch Method, the Saturated Filter Paper method and the Chloride-Specific titration tube method.
For climatic condition monitoring we can offer paint inspectors to conduct bi-metallic magnetic thermometer readings and electronic thermometers for temperature measurement using digital equipment, with wet and dry bulb hygrometers and electronic dewpoint meters for the measurement and data-logging of relative humidity and dewpoint temperatures also. Oven temperature logging and wind velocity measurement are also available using anemometer.
For coating thickness checks we can offer our inspection services on wet film combs, mechanical and electronic non-destructive testing dry film thickness gauges and the destructive paint inspection gauge (PIG).
Finally for those post curing assessments of adhesion and porosity we highly recommend our coating inspection services offering a full range of adhesion testers and low and high voltage holiday detectors.
