Guide to Holiday Detector


The purpose of a coating or a covering layer is to isolate the underlying material by external factors like corrosion.
In order to perform a maintenance control or check the quality of a coating process Holiday Detector (or Pinholes Detector) can determine presence of micro-holes , porosity or thinning in conductive coatings.


The term “Holiday”, dates back in the era of  transoceanic navigation by sailing boat . Maintenance during long voyages was essential.
One of  the most important tasks was to maintain masts coverage that would otherwise have been exposed to weather and salt and destined to rot.
If a single part had remained uncovered it would have compromise mast integrity and navigation capacity.
When this happened sailors used to make fun saying that the sailor in charge had taken an “holiday”.
Even if steel has replaced wood, the term “Holiday” is still used  when we need quality and usury controls or we need to know the status of a coated surface.


Holiday detector is composed by a main unit that can provide a constant and adjustable voltage, an insulating handle and a probe that transfers tension to the inspected surface.

The most modern models can advise operator in many ways.


•  Audible alarm : a buzzer or headphones (included) highlight porosity
•  Visual alarm :sparking or light signals the handle





The instrument conforms to the following standards:


ANSI/AWWA C 214-89

ANSI/AWWA C 214-91

AS 3894.1

ASTM D 4787


ASTM D 5162


BS 1344-11

ISO 2746

JIS G-3491

JIS-G 3492

NACE RP 0274

NACE RP 0490-2001

NACE RP 0188-88

DIN 30672

DIN 30670




Check integrity of covering allow to detect coating discontinuities by an electrode connected to high voltage AC or to pulsed current.
In presence of a discontinuity creates an electrical discharge between the electrode and the substrate, the device alerts the operator through acoustic and optical signals



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