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30 SEPTEMBER 2016 COATINGSPROMAG.COM coatings inspectors working for owners, contractors, third party agencies, and coating manufacturers. Inspector training and certification to different levels is offered through organizations such as NACE International and SSPC: e Society for Protective Coatings. Contractor certification programs maintained by SSPC, NACE, and third party coating inspection firm certifica- tion programs like SSPC-Qualification Procedure (QP) 5 contain requirements for calibrated instruments that are used to verify the quality of workmanship. While not specifically mandated by these organizations, it is prudent to have instrumentation that is used in the quality process calibrated at least annually. In fact, most instrument manufacturers will recommend a 12- to 18-month interval for re-calibration. e interval is oftentimes based on frequency of use, degree of wear and tear, the environment within which it is used, and other factors. Managing the Calibration Process Painting contractors represent a signif- icant segment of the demographic for inspection instrument sales. Maintaining an instrument calibra- tion/certification program and the associated due dates can be very challenging, even when you have a staff dedicated to the program. If you are a mid- to large-size painting contractor, it requires a significant investment in time and dollars to maintain an effec- tive calibration/certification program for inspection instruments. Keeping inspection equipment calibrated should not be considered a paperwork exercise. It helps to ensure the work truly does conform to the contract requirements, resulting in less rework and a stronger reputa- tion in the industry. Companies that sell coatings inspection instruments often have calibration programs that effectively remove the burden of managing the calibration process from contractors and other large users of inspection instruments by tracking the instruments they have and, when the calibrations are due, performing calibration and managing repairs as necessary, all while returning the calibrated equipment as efficiently as possible to minimize downtime. Some companies even offer loaner gages if the repair process is projected to be lengthy. Differentiating Calibration From Verification of Accuracy and Adjustment Our industry has defined calibration as the high-level, controlled, and documented process of obtaining measurements on traceable standards over the full operat- ing range of the gage. While we typically associate calibration with dry film thick- ness gages, most inspection equipment can be, and needs to be, calibrated. It is also important not to confuse calibra- tion with "verification of accuracy" or to use the terms synonymously. Verification of accuracy is performed far more frequently, even daily, while, as already noted, calibration is often an annual event. is difference is explained in detail a little later. Calibration should be performed by the gage manufacturer, its autho- rized agent, or by an accredited calibration laboratory. Calibration must be performed in a controlled environment that is not typically found in a shop or in the field. Verification of accuracy, on the other hand, is performed by the inspec- tor and does not need to be performed in a controlled environment. Based on the accuracy verification process, adjustments may be made to the instruments to compensate for shop or field conditions during the measure- ment process. ASTM D7091: Standard Practice for Nondestructive Measurement of Dr y Film Thickness of Nonmagnetic Coatings Applied to Ferrous Metals and Nonmagnetic, Nonconductive Coatings Applied to Non-Ferrous Metals and SSPC Paint Application (PA) 2: Procedure for Determining Conformance to Dr y Coating Thickness Requirements both contain information on calibration, verification of accuracy, and adjust- ment. Incidentally, all three of those are required prior to obtaining coating thickness measurements when one or both of these standards are invoked by the project specification. For electronic gages (known as Type 2), verification of accuracy is performed using traceable, certified coated standards or using certified shims placed on a smooth substrate. is is typically accomplished by using coated standards or shims that are slightly below and slightly above the anticipated dry film thickness range (known as two-point verification). SSPC-PA-2 states that verification of accuracy should be performed (at a minimum) at the beginning and end of each work shift, and recommends verifying accuracy during measure- ment acquisition, especially if a large number of readings are being obtained or the gage is dropped or suspected of being out of tolerance. is step makes certain that the gage is working properly, but another step, adjustment, is necessary before using the gage to measure coating thickness. Adjustment is the act of aligning a gage to correct for substrate metal- lurgy, curvature, roughness (including surface profile), and other characteris- tics that may affect the measurements. is is accomplished by placing certified or measured shims onto the prepared, uncoated substrate and adjusting the gage to align with the shim value (or measuring and deducting a base metal reading). One- or two-point