Webinar15:00

Elcometer Webinar: Profiled Surface Calibration

This webinar will cover international standards, calibration methods, and answer common questions about gauging on profiled surfaces. Craig and other Technical colleagues will be available to answer your queries.

Craig Woolhouse

Published Thursday 18 February 2021

In this article

presented by

Craig Woolhouse, Elcometer

About the presenter

Craig Woolhouse Bio

Craig, a qualified Mechanical Engineer, joined Elcometer 18 years ago as Sales Manager for UK and Europe. 2009 saw the addition of India and Africa as regions within Craig's area of responsibility. Elcometer view both areas as key growth regions and thus deserving of specific management and support from the Company's Head Office. Craig is very involved in training and presenting and is very qualified to comment on latest developments within the market.

Webinar topics

The webinar will cover the following topics:

International Standards
- SSPC PA2, ASTM D 7091, ISO 8503
Calibration
- Rough and Smooth
Rough Calibration
- Determination of the "zero"
Zero Offset Calibration
Calibration Data

Date, time and RSVP

Details as follows:

Date: Thursday 18 February 2021

Time: 15:00

Platform: To be advised. Please RSVP in order to receive the link.

RSVP: If you would like to participate in the webinar please RSVP

Previous webinar recordings

If you missed the previous webinar recordings then please feel free to access them here:

The first minute is just a count down so you can start at 1 minute.

Soluble Salt Measurement Development: (41 minutes)

Video summary

Elcometer Soluble Salt Profile Gauge: Advanced Chloride Measurement on Pre-Coated Surfaces

The new Elcometer soluble salt profile gauge measures 252 individual readings per test to reveal the actual distribution of chloride contamination, rather than just reporting a single average value like traditional Bressler patch and filter paper methods
The gauge provides selectable data output modes (B mode for Bressler-equivalent results, E mode for filter paper-equivalent results) and includes 2D and 3D visualization, four-quadrant Bressler-sized area breakdowns, and pass/fail analysis against user-defined limits
Peak contamination levels are more relevant to corrosion risk than averages, since chloride salts crystallize randomly during moisture evaporation and form isolated concentrations rather than uniform layers
The test time is reduced to approximately 2.5 minutes, consumable costs per test are lower than Bressler patches, and payback of the higher initial equipment cost occurs within 320 tests when labor costs are included (roughly 3 months at 3 tests per day)
The gauge offers integration with Elcometer's data management software for automated report generation, includes a magnetic pad accessory to prevent paper evaporation and displacement, and has received recognition including NACE Product of the Year 2017

Craig Woolhouse from Elcometer presented advances in measuring soluble salt contamination on steel surfaces before coating application. Inadequate surface preparation causes 75% of in-service coating failures, and chloride salts are the most common contaminant. Two traditional methods—Bressler adhesive patches and saturated filter paper tests—both provide only single average values despite salt contamination forming in randomly distributed crystallized concentrations. The new Elcometer profile gauge measures 252 individual sensor readings per test, creating detailed maps that reveal where peak contamination exists. The gauge can display results equivalent to either traditional method, show variation across four Bressler-sized areas, or present data as 2D and 3D heat maps and pass/fail compliance graphics. A magnetic pad accessory reduces water evaporation during testing. The test takes 2.5 minutes with lower per-test costs than Bressler patches and integrates with Elcometer reporting software.

Recording Attributes of a Coating Failure as Result of an Adhesion Test: (25.15 minutes)

Video summary

Pull-Off Adhesion Testing: Failure Types and Reporting

Pull-off adhesion testing provides objective measurement of coating adhesion by recording both the force required to remove a dolly and the type and location of failure within the coating system
Failures are classified as glue failure (adhesive bond failure), cohesive failure (coating fails within itself), or adhesive failure (coating fails between two layers), each with different implications for coating application and surface preparation
Failure location and type are recorded using standardized shorthand codes (e.g., cohesive failure within a layer uses one letter; adhesive failure between layers uses two letters) and quantified as a percentage of dolly face area
Adhesive failures typically indicate poor surface preparation, contamination, moisture, or incorrect surface profile, while cohesive failures suggest improper coating mixing or curing issues
Different gauge types (106/506 pull-off vs. 108 push-off) produce different results due to different test mechanics; ISO standards require cutting the coating while ASTM standards prohibit it, though either approach should be reported

This webinar covers pull-off adhesion testing standards, primarily ASTM D4541 and ISO 16276-1, which require reporting the type and location of failure alongside the adhesion force value. The test involves bonding a metal dolly to a coated surface with adhesive, then slowly pulling it off while recording the force applied. Modern digital gauges apply load continuously at specified rates and can record failure attributes automatically. Three failure types are possible: glue failure (adhesive bond issue, typically an invalid test), cohesive failure (coating fails internally), and adhesive failure (coating fails between two different layers). Understanding failure mode helps identify root causes such as surface profile deficiencies, contamination, or improper coating mixing. The webinar also addresses common questions, including why different gauge types produce different values and why curved dollies are used only with push-off gauges.

Surface Profile Measurement Methods: (33.54 minutes)

Video summary

Surface Profile Measurement: Replica Tape vs Digital Gauge

Both replica tape and digital gauge methods are recognized in ASTM D4417 standards, but they measure different parameters and will always produce different readings
User errors are common with both methods: replica tape requires full compression and correct tape grade selection, while digital gauges must be zeroed on a flat glass plate before each use
Digital gauges (like Elcometer 224) take 10 random readings and record the average, providing statistically valid sampling that avoids bias, whereas replica tape records only the maximum depth value within a 6mm sample area
Replica tape measurements capture extreme values and ignore up to 75% of potential profile values on the structure, making average and standard deviation calculations from tape data statistically invalid for predicting overall structure condition
The Elcometer 224 has a measurement range of 0 to 500 microns with plus or minus 5% accuracy, while replica tape accuracy varies by grade and can reach maximum acceptable errors of 24.4% at lower profile depths

Surface profile depth on blasted substrates can be measured using replica tape or a digital gauge, and both methods are standards-approved. However, they are not measuring identical parameters. The replica tape creates a 10mm diameter sample but only captures the maximum profile depth within the 6mm measurement window, introducing statistical bias. The digital gauge takes 10 random readings across a similar area and calculates the average, providing statistically representative data. User errors with tape include incomplete compression and using the wrong tape grade for the expected profile range; gauge errors stem from improper zeroing or taking only single readings. When averaging maximum values from tape versus averages from all gauge readings, the results can indicate different conclusions about specification compliance, so recording the measurement method used is critical.

Selecting a High Voltage Gauge: (34.42 minutes)

Video summary

High-Voltage Porosity Detection for Coating Inspection

Porosity testing detects coating defects by applying high voltage to exploit the coating's insulative properties; when defects are present, current flows and the gauge alarms.
Test voltage must be calculated using the coating's dielectric standard and minimum specified DFT (not measured DFT), with modern Elcometer gauges having standards pre-programmed to perform this calculation automatically.
Safety is ensured through low current design (typically 0.2 milliamps maximum), ribbed structures that dissipate static charge, and safety interlocks that disable voltage if the handle is released.
Two gauge types are available: the Elcometer 266 uses continuous DC voltage and requires a physical earth return cable, suited for internal low-contaminant environments; the Elcometer 280 uses pulsed DC voltage with a trailing lead, better suited for external dusty or damp environments.

This webinar covers high-voltage porosity detection techniques used to identify defects in protective coatings. The test works by applying a voltage to a coated surface; when coating defects are present, the insulative properties break down and current flows, triggering an alarm. Proper setup requires selecting the correct dielectric standard from the coating specification and entering the minimum specified DFT, allowing the gauge to calculate the appropriate test voltage. Elcometer gauges incorporate safety features including low current output, built-in meters that continuously monitor and adjust output voltage to maintain specification, and protective design elements to prevent static shock to users. The choice between continuous DC (Elcometer 266) and pulsed DC (Elcometer 280) technologies depends on the application environment.

Got a question about this, or need help picking the right instrument for your job? , our product assistant.

About the author

Craig Woolhouse

Thursday 18 February 2021

Technical specialist at BAMR. Has spent years advising coating inspectors at industrial sites across southern Africa on instrument selection and compliance requirements.

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