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The Model M/1S Holiday Detector Kit includes the following:

(1) Model M/1S Unit (085-155)

(1) Battery, 9v (010-007)

(1) Cable, Ground (026-101)

(1) Water Wetter Solution, 4oz (049-013)

(1) Wand, 16” (177-070)

(1) Sponge Assembly (ships assembled)

(1) Sponge (055-882)

(1) Holder, Yellow (076-050)

(1) Knob, sponge holder (094-030)

(1) Sponge bracket (014-195)

(1) Canvas tote bag

(1) Warranty Registration Card

(1) Instructions

The information contained in this document is subject to change without notice and does not

represent a commitment on the part of Tinker & Rasor.

Any and all reproduction or transmission of any part of this manual, in any form or by any means

and for any purpose other than the personal use by the purchaser is strictly forbidden without the

express written authorization of Tinker & Rasor.


The Model M/1S Holiday Detector is a highly sensitive device designed to locate holidays (pin

holes, voids, etc.) in thin film protective coatings of relatively high electrical resistance when such

films are applied to the surface of material of low electrical resistance. In these applications, such

as painted metal surfaces, the Model M/1S Holiday Detector will locate these points very accurately

with an audible and visual signal. This method of inspection of thin film is a non-destructive test

and will not injure the protective coating.


The Model M/1SHoliday Detector consists of a portable battery powered electronic instrument, a

wand handle, and sponge assembly (open cell sponge ships compressed, will expand with water),

and ground wire. The instrument is housed in a sturdy plastic case with provision for attachment of

optional (not included) headphones.

The detector is a “non-destructive wet sponge” type holiday detector. The basic electronic design

of the Model M/1S Holiday Detector is that of a very sensitive circuit which is energized by one 9v

battery. When current of 500 or 700 (+/- 10/%) micro-amperes flows in the circuit, an audible and

visual signal is actuated.

The test lead wire used in the ground wire can handle a minimum of 100 milliamps at 100 volts. If

replacement or additional wire is needed, make sure it meets these requirements. Up to 100’ length

of ground wire does not adversely affect the detectors operation, in most cases. If adding additional

ground wire, 14 AWG stranded or equivalent is recommended.

The exploring electrode is open-cell sponge material and is conductive when saturated with a

wetting solution. The sponge electrode is attached to the non-conductive wand handle by means

of the bolt with knob, plastic sponge holder and backing plate.

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The wetting solution should consist of potable tap water and a wetting agent. The ratio of one (1) ounce agent to one (1) gallon tap water is recommended. Tinker & Rasor WATER-WETTER© is a non-sudsing wetting agent, available in 8 oz. bottles, factory direct or through stocking distributors.


The protective coatings should be dry and free of all contamination prior to electrical holiday testing. Proper curing and drying time of the protective coating must be established prior to conducting electrical holiday testing.

Note: Solvents retained in the protective coating film can cause erroneous indications (false

holidays) during electrical testing.

The dry film thickness should not exceed 20 mils when electrical holiday testing is done with the low voltage Model M/1SHoliday Detector. Film thickness should be determined with a nondestructive dry film thickness gauge to make sure limits are not exceeded.

Special Note: Ordinary tap water will generally suffice to dampen the sponge electrode,

provided the protective coating thickness does not exceed 10 mils. The factory

recommended practice is to use a wetting agent at all times, regardless of coating

thickness to 20 mils.

Check battery voltage. This can be done by shorting the terminals of the holiday detector. If a steady, level audible signal is heard, the battery voltage is OK. If the audible signal starts to attenuate while testing, REPLACE battery.

Note: A battery output voltage drop of over 10% also indicates weak battery.


Assemble the Holiday Detector by first connecting the ground cable to the handle. Insert the ground

cable connector into the handle, and then rotate one quarter turn counter clockwise to lock. Connect

the wand handle to the front (nose) of the instrument and screw down until firmly seated. Finally,

attach the sponge bracket (aluminum piece), sponge, sponge holder (plastic piece) and the knob

with threaded bolt through all and screw down on the wand end. Saturate the sponge in a wetting



The sponge electrode should contain sufficient amount of wetting solution to assure moisture penetration from the sponge electrode into any defect that may be present in the protective coating. Excess wetting solution should be squeezed out of the sponge electrode.


Attach ground wire directly to the bare structure (substrate) under test. On coated steel structures the ground wire must be directly connected to the bare metal.


On coated concrete structures the ground wire should be connected directly to the reinforcing steel embedded in the concrete. If rebar is not present, a ground connection to the concrete can be made by placing the bare end of the ground wire against the bare concrete surface and anchor it down with a burlap bag filled with damp sand.

The ground wire can be checked quickly for proper connection by contacting the wetted sponge

electrode to the bare structure and observing an audible signal, indicating correct electrical

continuity of the holiday detector circuit.

The rate of inspection speed of the sponge electrode over the protective coated surface should not

exceed sixty (60) linear feet per minute. Using a double stroke of the sponge electrode over each

area assures better inspection coverage with less likelihood of any missed areas.


Factory calibration on Model M/1S Holiday Detectors is set at 700 micro-amperes (+/- 10%) of

current flow to complete the circuit for the audible signal to indicate a coating holiday on metal

substrates. For coatings on concrete substrates, the Model M/1S must be adjusted for current flow

of 500 micro-amperes (+/- 10%).


Model M/1S Holiday Detector sensitivity may be verified by simply depressing push buttons on the

front of the instrument. The instrument is Factory set for use on steel structures.

For use on steel structures, depress BLACK button (80K); Detector should signal and LED will

light if detector is in calibration.

Depress RED button (90K): Detector should NOT signal and LED will NOT light if detector is in


If the detector signals when either the BLACK button (80K) or the RED button (90K) is depressed,

the unit is set for concrete structures. The adjustment is a small jumper setting on the main circuit


If the BLACK button (80K) fails to signal, the instrument is not in calibration and should be sent for

Factory calibration.


Holiday Detectors returned to the factory for repairs should be sent TRANSPORTATION PREPAID.

In most cases the detector can be repaired and returned the same day it is received at the factory.



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