Holiday testing: define the coating continuity check

Identify the continuity decision in the specification

For a Saskatoon commercial facility purchasing a new protective coating on steel, start with the inspection requirement in the proposed system. Ask the specifier which components require continuity testing and what acceptance decision the results support. Do not add this inspection to every decorative repaint merely because an instrument is available.

DeFelsko describes holidays as small regions of thin or missing protective coating. Its guidance notes that discontinuities can remain where dry-film thickness is sufficient and may escape visual detection. This explains why a thickness report or attractive finish does not answer the same question as a specified continuity check.

Give the inspector a component list and the proposed coating documents. Identify whether the work is a new system or an existing coating that has already been in service. Keep ordinary architectural finishes and unidentified existing layers outside an assumed test scope until the responsible specialist reviews them.

Reference: DeFelsko: discontinuities can exist despite sufficient film thickness

Obtain a system-specific inspection proposal

ASTM's public D5162-24 overview concerns electrical discontinuity testing of nonconductive protective coatings on metal. It calls for an agreed allowable discontinuity count before testing and manufacturer consultation about cure and conductive ingredients. Its discussion also cautions that testing previously immersed linings can produce misleading results or damage. These limits make system identity and service history part of commissioning.

Request the inspector's method reference, applicable edition, suitability rationale and readiness requirements. Have the coating supplier resolve any uncertainty about the specified system. Leave instrument selection, settings and execution with qualified personnel. This buyer guide supplies no test voltage, operating procedure or acceptance threshold.

Ask who arranges safe access and controls the work area. Price inspection separately from any access equipment, corrective coating work and return visits. A general inspection allowance should identify which of those responsibilities it includes. The public standard overview is background for these questions; it does not replace the complete method or a project-specific inspection plan.

Reference: ASTM D5162-24: public scope and significance, particularly 4.2, 4.5 and 4.6

Make tested coverage and repair locations traceable

Request a component map that distinguishes tested surfaces, inaccessible areas and work excluded from the assignment. Have the reviewer state whether those limits satisfy the agreed requirement. A report saying no indications were found needs its coverage boundary beside it; the owner should not have to infer that every concealed face was examined.

For an illustrative commercial steel assembly, one face might remain obstructed during the first inspection. Record that face as unresolved and agree how access and review will be completed. The example does not establish a sampling rule or authorize acceptance of an untested surface.

Where an indication requires correction, give it a location reference that follows the repair proposal and subsequent inspection. Ask who specifies the compatible repair, who performs it and what evidence closes it. Keep the original finding visible alongside the later result so a repair invoice cannot silently become a passed retest.

Close continuity without expanding the conclusion

Have the responsible reviewer reconcile the original inspection, repaired locations, follow-up results and any remaining exclusions. Record the decision against the agreed continuity requirement. Obtain separate decisions for other specified properties; a completed continuity assignment does not by itself establish adhesion, chemical suitability or an operating release.

Retain the coating identity, inspection plan, location records and closing decision together. Bring these requirements into an industrial coating discussion with PainterzRus and confirm the services actually offered. Specialist testing and interpretation require explicit arrangements. This article makes no claim that PainterzRus owns holiday detectors, provides certified inspections or guarantees protective-coating performance.

Does an acceptable thickness report remove the need for specified holiday testing?

No. Thickness and continuity answer different questions. Ask the responsible specifier to resolve the inspection requirement explicitly; do not omit it merely because the thickness results are acceptable.

Put the planning into practice

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Discuss your commercial project

For warehouse or light-industrial work, explore the access, surface-condition and downtime questions covered by our industrial and warehouse coating planning service.

Have a location and a rough scope? Request a commercial painting quote with the details you have. Access, timing and project requirements can then be reviewed for your property.