PCWI Compact Wet Sponge Pinhole Detector

This Holiday detector uses the low voltage wet sponge method to detect pinholes (holidays) in coatings.

Model available: 9, 67,5 and 90 volt Selectable.

Proudly manufactured in Australia by PCWI.

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PCWI Compact Wet Sponge Pinhole Detector

These units are also known as wet sponge testers, low voltage holiday detectors, low voltage porosity detectors and pin hole detectors.

Complies with the requirements of

AS3894.1-2002 (Wet Sponge Testing); ASTM G62-07; ASTM G60-07; ASTM D5162-08; Nace Standards: RP0274-2004 & SP0188-2006


  • Uses the wet sponge method to detect pinholes in coatings


  • LED display of voltage
  • Internally mounted 9V battery
  • Low battery condition LED indicator
  • Audible and visual fault alarms
  • Telescopic handle for user comfort (extends to 1.2m)
  • Large probe head (230 x 40mm) and wider sponge allows for faster testing
  • Earphone jack to allow testing in noisy environments (earphone not supplied)

Kit Comprises

  • Unit and Handle including Sponge
  • Belt / pocket clip
  • Seven metre earth lead and clip
  • Carry case
  • Instruction manual with Calibration certificate


The video below compares wet sponge detectors with high voltage detectors and is worth watching when considering the purchase of a wet sponge detector.



Proudly manufactured in Australia by PCWI.

View FileDatasheet - PCWI Wet Sponge Pinhole Detector    Size: (292.47 KB)
View FileProduct Manual - PCWI Wet Sponge Pinhole Detector    Size: (1.9 MB)

View all FAQ's

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  • What is the function of PCWI Detectors?

    PCWI Detectors are test instruments that detect and indicate the location of pinholes and bare spots (Holidays) in non-conductive coatings, linings or films that have been applied for corrosion protection on metal and concrete surfaces.

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  • What types of non-conductive coatings are applied in corrosion prevention?

    Thin epoxies, vinyls, paints, polyethylene, rubber, porcelain, enamels etc, hot applied coal tar, asphalt, and heavy mastic materials. Most anti-corrosive coatings are of a dielectric material and in order to detect defects through these surfaces a suitable test voltage is applied.

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  • What is corrosion and how is it caused?

    Corrosion is the gradual wearing away to destruction of material. It can be caused by atmospheric exposure or by chemical reaction with corrosive agents – hence the necessity to apply complete sealing coatings to eliminate moisture permeable defects.

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  • When would a PCWI Detector be used?

    PCWI Detector would be used both pre and post installation by the contractor (manufacturer), to confirm the efficiency of his original sealing coat, and by the maintenance engineers in periodic examinations.

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  • In what industries is corrosion of major concern?

    Because corrosion is of serious concern over almost all aspects of industry, both operationally and cost-wise, a short list of major industries would include: Mining: Fabrication: Engineering and Construction: Paint Companies: Oils and Petrochemicals: Municipal and Government Authorities such as City Councils, Electricity, Water and Sewerage, Defence: and so on.

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  • How is the testing of coatings by PCWI Detectors cost effective?

    For newly constructed tanks, pipelines and other installations where corrosion prevention coatings have had to be applied, specifications will normally call for a specific coating to a specific thickness. With the use of a PCWI Detector in verification of the competency of the sealing coating, the contractor can be assured that his coatings responsibility has been met. In terms of cost effectiveness, with the low capital and operating costs of PCWI Detectors, the contractor will have substantial freedom from claims at a very low price. The approximate labour time in PCWI Detector checking should be no longer than the time taken for a single spray coating application by power equipment.

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  • It is noted that the PCWI High Voltage Detector employs wire brush inspection electrodes and not wet sponges. What are the advantages of the wire brush electrodes and the limitations of the wet sponge detectors?

    High voltage testers with wire brush electrodes are faster to use, larger areas can be covered and there is no contamination from the water.

    Wet Sponge (cellulose) electrodes are used in low-voltage detectors, having an output of less than 100VDC. The wet sponge method is not satisfactory for the detection of other than gross faults in thin film coatings, and is unsuitable for use where thicker coatings in excess of 150µm have been applied.

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  • It is stated that under practical conditions, it is impossible to obtain an absolutely uniform thickness of an applied coating to a metallic surface, due to unevenness, mill-scale or other surface blemishes. Using a “dry testing technique” by applying a high test-voltage to locate faults over the thickest section of the film, the thin areas of film could be ruptured due to excessive test voltage, even though these thinner film areas are perfectly homogeneous. Under these circumstances wet sponge testing utilising a low voltage can be effective - True or false?

    This is False! Rupturing will only occur if far too high a voltage is applied when testing. Passing the electrode over a test panel with similar (thinner) coating thickness will quickly determine whether the voltage is set to a level that will cause rupturing in the thinner areas.

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  • Does the PCWI Detector have earphones?

    Yes – Air operated.

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  • How are the Detectors cleaned?

    By wiping with a mild detergent or isopropyl alcohol. Do not use solvents or aggressive chemicals, turpentine etc as the housing is PVC based.

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  • On what principle does the low voltage wet sponge unit operate?

    The low voltage instrument employs a cellulose sponge as an inspection electrode. When moistened with water, the electrode is moved over the coated surface under inspection: when the electrode passes a void or bare spot, moisture from the wet sponge (electrode) penetrates the coating making contact with the conductive substrate, resulting in a drop in electrical resistance. As a result, a small current flow activates an audible alarm enabling identification of the defect location.

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  • Is the applied voltage user selectable?

    Yes, each unit has three settings: 9, 67.5 and 90 volts.

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  • What are the important operational features of the Low Voltage Units?

     •   Digital Display of voltage
     •   Unique correction system to minimise output voltage drop during testing
     •   Selectable output voltage: 9, 67.5, 90V
     •   Battery condition displayed in volts
     •   Auto shut down after 20 minutes to save batteries (can be overridden)
     •   Earphones for uses in noisy environments
     •   Light weight – single hand operation
     •   Telescopic probe handle – to 1.2m
     •   Internally mounted 9v replaceable battery
     •   Wide sponge probe head - faster testing

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  • Will Wet Sponge electrodes ensure good inspection in corners and around irregular shapes?

    Yes. The flexibility of the sponge ensures good inspection.

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  • What user comfort and safety do low voltage units provide?

     •   Economically designed handle for easy use – single handed
     •   Large brush for faster testing
     •   Audible and visual alarm
     •   Seven metre earth lead & clip
     •   Belt/packet clip
     •   Weight 350gm (excl probe)

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  • Can Wet Sponge units be used in corrosive environments?

    Definitely not recommended.

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  • Does the PCWI Thin Film unit carry the CE marking?

    Yes: Together with other relevant International Standards. (see compliances)

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  • What certifications of compliance do PCWI Detectors carry?

    Australian Standard AS3894.1-2002. This standard sets the guidelines for equipment type, voltages for specific coating types and voltages applied. The Detectors also meets the EMC directive 89/336/EEC, amended 92/31/EEC & 93/68/EEC and carry the CE marking.

    However, due to the method of operation, PCWI Detectors will generate broadband RF emissions when a spark is produced at the probe, i.e.: when a defect in the coating is located. These emissions may interfere with the operation of sensitive electronic apparatus in the vicinity.

    In the extreme case of a continuous spark of length 5mm the magnitude of the emissions at a distance of 3m was found to be approximately 60dBµV/m from 30MHz to 1000MHz.

    It is therefore recommended that this equipment is not operated within 30m of known sensitive electronic equipment and that the user does not deliberately generate continuous sparks.

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  • Is AS3894.1-2002 accepted and/or would the Australian Standard comply with a relative International (ISO) Standard acceptable in other countries?

    We believe that AS3894.1 is the world leader in Porosity Standards and should satisfy all International criteria, as there is no equivalent International Standard for Porosity Detection.

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  • It is understood that the Australian Standard AS3894.1-2002 permits both DC high-voltage and DC pulse units for testing coatings of a depth thickness less than 500µm (micron)!

    The PCWI Detector has constant test voltage and current.

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Range 0 to 500 µm
Operating Temperature Range 0 °C to 50°C
Test Voltage 9, 67.5 and 90V
Telescopic Probe Length 350mm to 1.2m
Power 9V Battery
Dimensions 210 x 75 x 35mm
Weight 350g


Certification available.

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