The Micro-Metrics OG204 / OG214 Dual-Measure Tooke Gage 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 microscopic observation and measurement of substrate and film defects.
The Micro-Metrics OG204 / OG214 Dual-Measure Tooke Gage is 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. This tooke Gage is virtually the only tool for measuring paint on plastics.
Other uses of the Micro-Metrics OG204 / OG214 Dual-Measure Tooke Gage include assessment of substrate conditions and coating adhesion, and observation of microscopic cracking, tendency for brittleness, cratering, or other microscopic film symptoms.
The Tooke Gage uses an illuminated 50-power microscope equipped with the new Dual-Measure microscope with a measuring reticle marked in both mils and microns. 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 Gage 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.
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 molded polycarbonate plastic Gage 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 inspectors wrist. The entire unit is designed for convenience and completeness in field inspection tasks.
Two cutting tip holders are available
The anodized Dual-Measure microscope reticle is marked in mils and microns.
A special cutting tool (the cutting tip) that is integral to the Gage is used to incise a small precision V-groove through the paint film and into the substrate.
The Gage in standard configuration mounts 1X, 2X, and 10X cutting tips. (An optional 5X tip is available.) The Gage can be ordered in any desired configuration, such as with three tips of the same size. You may also order (for a lower price) a Gage with only a single cutting tip and two blank tips (spacers).
Measurement with a Tooke Gage is a function of the cutting tip face-angle and NOT of the microscope.
One of the best things about the new Dual-Measure scopes is the return to an easy calculation system related to the cutting tip face-angle. As described in the measuring demo, and shown in the drawings in the Geometry section, below, count the hashmarks spaces for each layer of coating, and then calculate the coating depth using the the Dual-Measure scope conversion shown below.
Conversion for the Dual-Measure scope:
| Cutting tip used: | Face Ratio | Each counted hash measures: |
| 1X | 1 : 1 | 1 mil |
| 2X | 1 : 2 | 1/2 mil |
| 10X | 1 : 10 | 1/10 mil |
Cutting tip diagram and ratio of cut-width : coating-depth
A Measuring Demonstration
The zero-line of the Dual-Measure reticle at right is not lined up with the edge of a coating (nor does it need to be, as any hashmark will do). The zero-line is off onto the brown top-coat, well beyond the edge of the incision.
If needed, the top of the top-coat can be made easier to see using the black marker provided with the Tooke Gage.In this photo, the darker brown of the top is easy enough to differentiate from the lighter tan of the interior of the top coat.
Thus, in the demonstration photo above,the thickness measured for each different tip face-angle will be:
Above the line on the Dual-Measure or the old-style scope (U.S. standard-units: 1 mil per hash)
| Coating | 1mil /hashmark space | 1 tip, mils | 2 tip, mils | 5 tip, mils | 10 tip, mils |
| A-to-B substrate top (do NOT measure) | 11.25 hashmark spaces | 11.25 | 5.6 | 2.25 | 1.1 |
| B-to-C Blue primer | 3.75 hashmark spaces | 3.75 | 1.9 | 0.75 | 0.4 |
| C-to-D Tan top-coat | 5 hashmark spaces | 5 | 2.5 | 1 | 0.5 |
Below the line on the Dual-Measure or the old-style scope (metric units: 20 m per hash)
| Coating | 20 m /hashmark space | 1 tip, m | 2 tip, m | 5 tip, m | 10 tip, m |
| A-to-B substrate top (do NOT measure) | 15 hashmark spaces | 300 | 150 | 60 | 30 |
| B-to-C Blue primer | 4 hashmark spaces | 80 | 40 | 16 | 8 |
| C-to-D Tan top-coat | 7 hashmark spaces | 140 | 70 | 28 | 14 |
Precision and calibration:
Note:Every microscope is validated before sale against a certified Gage blocks traceable to the National Institute of Standards & Technology (NIST). An OEM calibration certificate can be ordered (for cost) with your new Gage or your Gage can be sent in for calibration and certification.Call or email for details.
Micro-Metrics CTH01 Cutting Tip Holder
Micro-Metrics CTH02 Cutting Tip Holder
| Micro-Metrics OG204 / OG214 Dual-Measure Tooke Gage - Data Sheet |
| Micro-Metrics OG204 / OG214 Dual-Measure Tooke Gage - Dual-Measure Scope Swap Program |
| Micro-Metrics OG204 / OG214 Dual-Measure Tooke Gage - Old Style |