Micro-Metrics OG202 / OG212 Tooke Paint Inspection Gauge II

Price: $ 975.00 up to $ 1,160.00
Tooke Paint Inspection Gage II
The original Micro-Metrics OG202 / OG212 Tooke Paint Inspection Gauge II / Gauge is made of machined aluminum.
In accordance with ASTM D4138

The Micro-Metrics OG202 Tooke Paint Inspection Gauge II is a precision tool for inspection and dry-film thickness measurement (in accordance with ASTM D4138) of single or multiple coats on any substrate, and for micro-scopic observation and measurement of substrate and film defects.

The Tooke Gage uses an illuminated 50-power microscope equipped with a “universal scope” with a measuring reticle that accommodates measurement in mils, microns, and millimeters. The gage mounts three tungsten carbide cutting tips for precise incision of the work surface. Standard cutting tips are 1X, 2X, and 10X. (An optional 5X tip is available.) Also, a gauge can be ordered with any three tips desired, or with a single precision-ground tip and two blanks.

Direct measurement of total dry-film coating thickness and thickness of individual coats of paint is a unique capability of the Tooke Paint Inspection Gage. Thus, in addition to routine use, it often serves as a “referee” instrument to calibrate indirect or non-destructive thickness measuring instruments.

(Note: Each universal microscope is validated before sale against a certified gage block traceable to the National Institute of Standards & Technology (NIST). An OEM calibration certificate is available for an additional fee.)


The Tooke Gage has been used to assess sandblast cleaning work, to measure plating and paint thickness on ceramics, metal, wood, and concrete, and even to measure protective backing thickness on mirrors. It is virtually the only tool for measuring paint on plastics. The quality of the incision in the film discloses much about the characteristics of the brittleness and adhesion of the material.

Other uses include assessment of substrate conditions and coating adhesion, and observation of microscopic cracking, tendency for brittleness, cratering, or other microscopic film symptoms.


The anodized OG202 with the universal microscope with a reticle selected to allow measurement in terms of mils, microns, and millimeters.

The aluminum gauge body contains an illuminated microscope and mounts three tungsten-carbide cutting tips (that incise the “V-groove” for measuring) on the narrow side. Two guide studs project from the body on the same side as the cutting tips. The tripod thus formed by the three legs (guide studs and cutting tip) provides precise alignment of the tool with the surface to be grooved. A lanyard with keeper looped through the body secures the instrument to the inspector’s wrist. The entire unit is designed for convenience and completeness in field inspection tasks.


  • A special cutting tool (the cutting tip) that is integral to the gauge is used to incise a small precision V-groove through the paint film and into the substrate.
  • Incising the V-groove with the anodized OG202 Tooke Gage
  • Using an older version of the OG202 Tooke Gage with a universal scope
  • Tooke Gage cutting tips are precision-ground from tungsten-carbide blanks.
  • Cutting tips are precision-ground from tungsten-carbide blanks.
  • The gauge in standard configuration mounts 1X, 2X, and 10X cutting tips. (An optional 5X tip is available.)
  • The gauge can be ordered in any desired configuration, such as with three tips of the same size.

Cutting tip ratios: A to A'

TipFace angleRatio
1X45° 0'A : A' = 1 : 1
2X26° 34'A : A' = 1 : 0.5
5X11° 18'A : A' = 1 : 0.2
10X5° 42'A : A' = 1 : 0.1

The tip slot is marked for the standard tip arrangement (in the anodized body).


Close-up of a non-standard arrangement of tips, a 1X tip extended for use and two blanks, mounted in a (very) old-style gauge body.

Principle: using the universal microscope

The incised V-groove is observed vertically through an illuminated microscope bearing a measuring reticle (scale). The OG202 is equipped with a “universal scope” that has a reticle that accommodates measurement in mils, microns, and millimeters. (The universal scale is metric, so conversion is necessary for English units.)

The universal microscope reticle is marked in 0.05mm (50µm) per hashmark

Reading the universal microscope

Note that in the photo below, the zero-line of the reticle is not lined up for the actual measurement (nor does it need to be; any hashmark will do). The gray/silver-colored “line” is the metal substrate; the white “line” is the (inside of the) green coating, which is what is measured visually through the scope. (See below for a different annotated version.) The cutting tip “draws” the (specifically-angled, depending on the chosen tip face) incision, which allows for calculation of the coating thickness. In this photo, the black marker has not been used to make the edge (top) of the green coating more easily seen.

Annotated close-up through universal scope

Thus, in this photo and using a “universal” scope (0.05mm hashmark space), the thickness measured for each tip equals:

1 X tip “white primer” = 2 reticle/hashmark spaces = 100 µm
“blue topcoat” = 5 reticle/hashmark spaces = 250 µm
2X tip

“white primer” = 2 reticle/hashmark spaces = 50 µm

“blue topcoat” = 5 reticle/hashmark spaces = 125 µm

10X tip

“white primer” = 2 reticle/hashmark spaces = 10 µm

“blue topcoat” = 5 reticle/hashmark spaces = 25 µm


Smallest hashmark measures in:
1X tip - Mils*2(1.97)
1X tip - Microns**50(50.0)
1X tip - Millimeters0.05(0.050)
2X tip - Mils*1(0.984)
2X tip - Microns**25(25.0)
2X tip - Millimeters0.025(0.025)
10X tip - Mils*0.2(0.197)
10X tip - Microns**5(5.0)
10X tip - Millimeters0.005(0.005)
* 1.0 mil = 0.001" = one thousandth of an inch 
**micron = micrometer (µm) = 1,000,000th of a meter

Universal reticle specifications

The machined aluminum Tooke Gage comes ready for use in a polycarbonate plastic carry case with two spare batteries, a spare LED bulb, a marking pen, a hex wrench, and a technical data sheet.

  • Standard cutting tip configuration is 1X, 2X, and 10X.
  • An optional 5X cutting tip is available.
  • Any configuration of tips may be requested (for example, three 10X tips; or a 1X, 2X, and 5X).
  • You may also order (for a lower price) a gauge with only a single cutting tip and two blank tips (spacers).
MaterialMachined anodized aluminum body
Overall dimensions4.5" x 3.5" x1"
11.4cm x 8.9cm x 2.5cm
Microscope50-power, 45-degree, illuminated
PowerTwo 15V AA drycells in the gauge, 
plus two spares
LampLED 222 bulb plus a spare bulb
Cutting tipsPrecision-ground tungsten-carbide:
1X, 2X, and 10X (or as desired)
Shipping Weight~2 pounds (0.9 kg)

Photo Gallery

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