Elenor’s notes: I’ve put the files and graphics up on the web here:

http://www.snowstarjean.com/Dual-Measure_web/ A file named: Clean.html and a directory with the graphics to download.

This file is really basic HTML/CSS.

I did include some links and anchors (added referrals within the page and to the M-M site for info, e.g. the Microgroover); and a link to the “Measuring” white paper on my site for cutting tip and measuring info. That paper is not yet updated – haven’t fixed it for the new Dual-Measure stuff.…

New in 2020: Dual-Measure Tooke® Gage!

Meets ASTM D4138-82; ISO 2808

OG2012 OG214

Direct measurement of total coating thickness, and thickness of individual coats of paint is a unique capability of the Tooke Gage. It features a Dual-Measure scope, with a reticle marked with 1 mil per hashmark space above the line and 20 microns below the line. Thus, in addition to routine use, it often serves as a “referee” instrument to calibrate indirect or non-destructive thickness measuring instruments. Other uses include assessment of substrate conditions and coating adhesion, and direct observation of microscopic cracking, tendency for brittleness, blistering, cratering, or other microscopic film symptoms.


  • Dual-Measure scope, with 1 mil per hashmark space above the line and 20 microns below the line scale.
  • Measures thickness of coatings applied to wood, plastic, cement, glass, ceramics, mirror backings, metal, etc.
  • Assists in measuring brittleness and adhesion of coatings and materials.
  • Models OG212 & OG214 are supplied with 1×, 2×, and 10× cutting tips installed in the gauge body. The 2× tip is shown extended to working position. An optional 5× cutting tip is available.
  • Gauges come in a rugged plastic carrying case with cutting tip wrench, indelible marker, spare LED bulb, and spare batteries

Dual-Measure scope testimonial

Oct 2019: Peter M., Product Quality Manager at a major industrial client:

The new reticles are AMAZING!
I have 2 more [gauges for scope swaps] in the mail for you and would like to purchase a new gauge as well.

FYI, I plan to purchase one more new one after this and will also send another 2 for new scopes after I get these back; that should take care of us.
Thanks again, these are AWESOME!

I can add that I took the Tooke to the line and watching my inspectors use the new gauge was like watching my kids at Christmas.

Measuring Procedure

Open the carrying case and remove the instrument. Check the positioning of the cutting tips. Ensure that the curved cut-out on the side of each cutting tip, the relief cut, is oriented toward the guide studs. This relief cut allows the coating(s) being incised to curl up and away from your incision, making for a cleaner incision. For field use, secure the safety lanyard to the wrist to prevent accidental dropping. As originally supplied, the tip positions will be from top to bottom 1×, 2×, and 10×. The numerals 1, 2, and 10 are engraved in the body alongside each tip respectively. The 1× and 10× tips will be bottomed in the slot. The operable tip should be extended into working position: in the photo below, the 2× tip is extended and secured so the narrow face of the gauge will be parallel to the surface to be incised. In general, the 2× tip extended is the correct configuration for making an initial measurement on a film.

extended operable tip

For detailed information on cutting tips and the measuring and calculating procedures, please see the PDF paper available here:
Measuring: the Geometry of the Tooke® Gage.
using tip wrench to switch cutting tip

An indelible marker is included in the Tooke Gage kit. Marking the top before incising in not required; however it may help determine where to stop counting hashmarks. If you can easily differentiate between the “slope“ formed by the incision and the edge marking the top of the coating, marking may not be helpful and can be skipped. Depending, too, on the coating color, other markers may be useful: Wite-Out® for dark colors or a silver- or gold-Sharpie® marker rather than the black one provided, may provided a clearer differentiation. Make a small mark with the marker, if used, at the desired measurement location on the coated surface. Grasp the instrument with the cutting tip down as shown below at left. Place the cutter tip and guide studs in firm contact with the surface with the tip slightly above the mark and aligned to scribe across the mark. (Note, at right below, the guide stud is not directly on the surface, so the cutting tip will not draw a correct incision.)

Align the forearm with the intended cutting direction to assure a straight cut. Draw the cutter tip straight across the mark, applying just sufficient pressure for the tip to cleanly penetrate through the film into the substrate. In this operation, the cutter trails midway between the two guide studs, and continuous 3-point surface contact should be maintained to ensure precise vertical alignment of the groove. Excessive pressure on the guide studs should be avoided. The incision does not need to cut deeply into the substrate; merely ensure the substrate is incised along your entire cut.

correct cutting position
Gauge held in correct cutting position
 wrong cutting position
Gauge held in INCORRECT cutting position

Turn on the microscope lamp with the slide switch on top of the case next to the eyepiece. Center the foot of the microscope on the scribed line with the mark about one-quarter inch from the foot directly under the microscope objective. Check the microscope for focus. If the image is not clear, it may be brought into sharp focus by turning the focusing screw in the body below the microscope. This may be quickly accomplished by using the supplied hex key wrench to loosen the tip set screws. Allow all three tips to bottom in their slots, then pull the selected tip out >to the correct height, matching the height of the guide studs and retighten all tips with moderate finger pressure.

Some users are required to have their Quality offices set the cutting tips. This varies depending on auditors and acceptable tolerances. If changing tips requires returning the gauge to a Quality office, a CTH01 or CTH02 – the single-tip and two-tip cutting tip holders – will allow the Quality office to set two or three tips at the required precision: one in the Tooke Gage itself, and either one or two in a holder. See the cutting tip holder section below for pictures and information.

With focusing accomplished, view the intersection of the mark and the cut as shown in Fig. 4a, below. Note how the “zero-line” of the reticle is not lined up with the edge of the primer coating (the white line to the left of the zero-line); it is approximately centered in the substrate (gray/silver line). (This was not intentional; lining up the camera moved the gauge slightly. Nor does it need to be lined up; any hashmark will do.)


A measuring demonstration

The universal scope is no longer available: all Tooke Gages now come with the Dual-Measure scope. However, since the cutting tip face angle determines your calculations, using the view through the universal gauge, left, shows the same process as through a Dual-Measure scope.

  • “Line A” is on the edge between the substrate and the beginning of the primer-coating: begin your measurement there.
  • “Line B” marks the top of the primer coating/beginning of the top coating (light blue).
  • “Line C” is the incision into the top coating, made easier to see by using the black marker provided with the Tooke Gage.

Count the hashmark spaces for each layer of coating. (For instance the top coat, B-to-C is 5 hash wide.) Important: The type of microscope your Tooke Gage is fitted with makes an absolute difference in calculating your measurement.

  • Using the mils-scale on the new Dual-Measure reticle, divide the number of hashmark spaces by the number designation of the cutting tip. So, if you used the 2× tip to draw your incision, you would divide the 5 hash by 2, which gives your your coating depth in mils (2.5mils). If you used the 1× tip (45-degree face), the ratio is 1:1, so the coating depth would be 5 mils.
  • Using the micron scale on the new Dual-Measure reticle, use the same division (1× tip = 1:1; 2× tip = 1/2 the counted hash; 10× tip = 1/10 the counted hash) but multiply your calculated count by 20 microns to get your coating depth.
    • Using the older “universal” scope, with its reticle marked in 50microns per hash, you use the same division (1× tip = 1:1; 2× tip = 1/2 the counted hash; 10× tip = 1/10 the counted hash) but multiply your calculated count by 50 microns to get your coating depth.
  • Measurements made using the Tooke Gage are a function of the cutting tip geometry (and not of the microscope). A detailed explanation of the geometry of the Tooke Gage called “Measuring: the Geometry of the Tooke Gage” is available.

Measurement with a Tooke Gage is a function of
the cutting tip’s precision-ground face angle
NOT of the microscope.

Measuring demo using universal scope

Dual-Measure reticle scale

Dual-Measure scope testimonials

NACE International instructor: April 2018 wrote:

It looks awesome. Love the new optics and the really easy-to-read scales.

Dual-Measure reticle scale



Measurement with a Tooke Gage is a function of the cutting tip 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 above, you 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:Each counted hash =
1×1 mil
2×1/2 mil
10×1/10 mil


For the scope conversion for the discontinued “universal” scope, see the Reticles section below.

The easiest example to follow in understanding the principle is demonstrated using the 1× cutting tip. In essence, you are incising a triangle into your coating by cutting the hypotenuse of a right-angle triangle. With the 45° 1× tip, you’re drawing an equi-lateral triangle. (See 1× figure below.) That is, the side of the triangle (the bottom of your view through the microscope), which you are measuring by counting the hashmarks across the ‘cut-width,’ equals the triangle-side that is your coating depth. That is, a 1 : 1 ratio with the 1× tip. With the 10× tip, you’re drawing a right-angle triangle, and one-tenth (1/10) the number of hashmarks across the cut-width is your coating depth. (See 10× figure below.)

The 1× tip with its cutting face of 45-degrees has a ratio of
1 : 1 so, A = A′ (i.e., measured cut A′ : calculated coating
thickness A) (“what you see is what you measure”).
The 10× tip with its cutting face of 5° 42′ has a ratio of
1 : 0.1 so, A = 1/10th of A′ (measured cut A′ : calculated
coating thickness A)
Ratio: 1× tip: A = A′
Ratio: 10× tip: A = (0.1) A′


Cutting tip details, including diagrams for the other two available tips, are available in the white paper called
Measuring: the Geometry of the Tooke Gage.”


Tip Angle Representation

Diagram of an incision made using a 1× (45°) cutting tip
drawing of incision
Diagram of incisions cut by three different cutting tips




Important note: Tooke Gages produced after November 2019 now have the new, custom-designed, custom-manufactured Dual-Measure scope and reticle. Tooke Gages produced between June 2010 and November 2019 are fitted with the “universal” reticle. The “universal” scope can be swapped out for the new Dual-Measure scope: contact your Tooke Gage distributor for information. Scopes from earlier than June 2010 (wht the green-anodized barrel) have the old-style English or metric reticles, and identical to the new Dual-Measure reticles.

Dual-Measure reticle
“Universal” reticle

The chart below shows the conversion basis for hashmarks on the “universal” scale produced between June 2010 and November 2019. For the hashmark conversion using the new Dual-Measure scope, see the Principles section above.

Calculating your coating depth as above, using counted hashmarks of the cut-width, visualized through the “universal” scope, each hashmark for the three main cutting tips will equal:

The (discontinued) “universal” scope conversion

Note that this table applies ONLY to the discontinued “universal” scope,
and NOT to the new Dual-Measure scope.

Calculating your coating depth as in Principles above, counting hashmarks of
the cut-width, visualized through the “universal” scope,
each hashmark for the three main cutting tips will equal:

Tip used: 1× 2× 10×
Mils 2 (1.97) 1 (.984) .2 (.197)
Microns 50 (50.0) 25 (25.0) 5 (05.0)
Millimeters .05 (.050) .025 (.025) .005 (.005)

Dual-Measure scope testimonials

NACE International instructor: May 2018 wrote:

As for the new gauge, I just ran it past another set of instructors yesterday. Same feedback as the team last week – they all love it. Sterling reviews. They love the optics and the lack of edge-to-edge distortion.


labeled OG212


The OG212 body is made of machined and anodized aluminum. The OG214 gauge body is made of injection molded high-impact plastic. The body holds the microscope and lamp batteries as well as the tungsten-carbide cutting tips mounted on the narrow side.

The tripod formed by the two guide studs and the extended / operable cutting tip provides for precise alignment of the cutting tip with the coating surface to be incised. A lanyard and keeper looped through the body secure the instrument to the inspector’s wrist. A plastic (polypropylene) carry case with foam inserts to carry your Tooke Gage and spare parts: marker, wrench, LED bulb, and spare batteries. The entire unit is designed for convenience and completeness in field inspection tasks.



Original factory/OEM calibration of the optics is performed on all gauges when assembled. If OEM certification is desired, it can be ordered at additional cost. Repeat calibration with certification is also available. Contact your Micro-Metrics distributor for details.


Suggestions to Users


Special Applications

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. As indicated above, the quality of the incision in the film discloses much about characteristics of brittleness and adhesion of the material. In addition to the benefits as a dry film thickness gauge, the Tooke Paint Inspection Gage offers the advantages of a close visual inspection tool.

Abnormalities that would otherwise go undetected by conventional electronic or magnetic gauges include pinholes, adhesion faults, deteriorated substrate conditions, and lack of overall coating integrity. Consider the Tooke Gage as an excellent adjunct to the conventional DFG and even more useful as a verification tool for the more exotic ultrasonic instruments.


CTH01 & CTH02 Cutting Tip Holders

CTH01 Cutting Tip Holder

double cutting tip holder

The CTH01 Cutting Tip Holder, at a little under two inches (4.1cm) long, allows easy use of a carbide cutting tip without having to manipulate the Tooke Gage to make the incision and then manipulate the gauge again to view the incision through the microscope. Make multiple incisions with your most-used tip without having to return the gauge to viewing position multiple times.

The cutting tip is secured by two set screws, one on the short end of the holder and one in the side. The wrench provided with OG212 and OG214 Tooke Gage fits these set screws. The two set screws give 90-degree support to the cutting tip. The cutting tip storage compartment on the opposite end holds two tips secured by a compartment retaining screw. double cutting tip holder

The CTH02 Double Cutting Tip Holder allows two tips to be mounted on opposite sides and, like the shorter, single cutting tip holder (CTH01), allows easy use of the cutting tips without having to manipulate the Tooke Gage to make the incision and then manipulate the gauge again to view the incision through the microscope. With this tip holder you can:

  • Make multiple incisions with your most-used tip(s) without having to keep switching the gage to viewing position.
  • Mounting Mount two of the same tips to allow for checking two incisions against each other.
  • "Bracket" your incisions by mounting two different tips to create different incising geometries.


Replacement tungsten-carbide cutting tips.

Available in 1× (45°), 2× (26.6°) and 10× (5.7°) configurations. An optional 5× tip (11.18°) and blank unfaced tips are also available. (The blank tips provides lateral stability for the operable tip, if only one faced tip is used.)

cutting tips


Carry cases

The Tooke Gage carry case – (included with gauge) is made of polypropylene with foam inserts to carry your OG212 or OG214 Tooke Gage and spare parts. With a convenient carry handle, the case closes securely with two latches and stands upright on two molded feet.




  1. “A Paint Inspection Gage” by Raymond Tooke, Jr., OFFICIAL DIGEST, July 1963, 35, pp. 691–698.
  2. “Coatings Adherence Measurement By An Angular Scribe-Stripping Technique” by W. R. Tooke, Jr. and J. Montalvo, JOURNAL OF PAINT TECHNOLOGY, January 1966, 38, pp. 18–28.
  3. “Development of Specifications For Measurement of Paint Thickness On Structural Steel” by J. D. Keene and T. L. Shoemaker, JOURNAL OF PAINT TECHNOLOGY, 45, No. 585, October 1973, pp. 46–67.
  4. “How Instruments Boost Coatings Application Productivity” by W. R. Tooke, Jr., PROFESSIONAL DECORATING AND COATING ACTION, October 1976, pp. 16,18.
  5. “Standard Method of Measurement of Dry Film Thickness of Protective Coatings Systems by Destructive Means,” Designation: D 4138-82, 1988 ANNUAL BOOK OF ASTM STANDARDS, pp. 695–697.
  6. “Method and Device for Measuring the Thickness of Films” by W. R. Tooke, Jr.