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PosiTest®

Magnetic Coating Thickness Gages for Non-Magnetic Coatings on Steel

PosiTest magnetic pull-off thickness gage (banana gauge) for the non-destructive measurement of non-magnetic coatings (paint, enamel, galvanizing, metalizing, plating, etc.) on steel.
  • Highly wear resistant Carbide Probe for longest life and continuous accuracy
  • Extra rugged housing, not affected by mechanical shock, water, acid or solvents
  • Unique overall design, fully supported, positive positioning, no pivoting tendencies during measurement
  • Positive visual and audible indicators to designate when thickness reading is established
  • “V” grooves in probe housing and gage base allow correct positioning on cylindrical objects
  • Certificate of Calibration showing traceability to PTB included (Long Form)
Conforms to ASTM D7091/B499, ISO 2808 and others
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Features

Accurate

  • Certificate of Calibration showing traceability to PTB included with every gage
  • Matching Calibration Standards and Procedures available for every model
  • Highly wear resistant Carbide Probe for longest life and continuous accuracy
  • Remove center of dial cover for easy calibration adjustment
  • Conforms to national and international standards

Durable

  • Extra rugged housing, not affected by mechanical shock, water, acid or solvents
  • Unique overall design, fully supported, positive positioning, no pivoting tendencies during measurement
  • Can be used fully supported or with only the front probe area contacting the surface
  • Functions on a permanent rare-earth cobalt magnet
  • No batteries/electronics
  • 2 year warranty
The PosiTest easily measures small parts of almost any shape
Easily measures small parts of almost any shape

Simple

  • Positive visual and audible indicators to designate when thickness reading is established
  • “V” grooves in probe housing and Gage base allow correct positioning on cylindrical objects
  • Compact, lightweight, precisely balanced, independent of gravity – can be used in any position
  • GO/NO-GO button can be pre-set for rapid measurement
  • Probe contact and dial rotation all in a one-finger operation
  • Furnished with wrist strap and instructions in a high quality leather case with belt loops for your convenience
carbide measuring probe for long life
Carbide measuring probe for long life

Models

Choose from four models:

illustration of PosiTest FM scale
PosiTest FM
Application
Hot dip galvanizing, hard chrome metalizing, paint, enamel, plastic coatings on steel.
Scale FM
0-80 mils
Tolerance:
± 0.2 mils up to 4 mils
±5% of the reading over 4 mils
View PDFAdd To Quote
illustration of PosiTest F scale
PosiTest F
Application
Hot dip galvanizing, hard chrome metalizing, paint, enamel, plastic coatings on steel.
Scale F
0-2000 µm
Tolerance:
±5 µm up to 100 µm
±5% of the reading over 100 µm
View PDFAdd To Quote
illustration of PosiTest GM scale
PosiTest GM
Application
Electroplating,
thin paint films, 
phosphating on steel.
Scale gM
0-8 mils
Tolerance:
±0.04 mils up to 0.8 mils
±5% of the reading over 0.8 mils
View PDFAdd To Quote
illustration of PosiTest G scale
PosiTest G
Application
Electroplating,
thin paint films, 
phosphating on steel.
Scale g
0-200 µm
Tolerance:
±1 µm up to 20 µm
±5% of the reading over 20 µm
View PDFAdd To Quote

Videos

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PosiTest - Magnetic Pull-off Thickness Gage
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Coating Thickness Instruments Overview

F.A.Q.

Is the PosiTest calibrated at the factory?

The PosiTest arrives fully calibrated and ready to measure. A Long-Form Certificate of Calibration traceable to NIST or PTB is included, which documents actual readings taken by your instrument at our calibration laboratory on standards traceable to a national metrology institute. Beware of ‘Certificates’ or ‘Certificates of Conformance’ offered by competitors. These typically do not include actual instrument readings, and are often insufficient to meet common quality requirements. The PosiTest features a rare-earth permanent magnet that prevents any kind of drift over time. A PosiTest gage that sits unused on a shelf for several years will not drift or lose its calibration.

Is the PosiTest intrinsically safe?

“Intrinsically Safe” (I.S.) is commonly used to describe electronic products destined for a hazardous (explosive) operating environment. Owing to the mechanical (non-electronic) design of the PosiTest, it does not require certification as an “intrinsically safe” device.

Why should I purchase the PosiTest over the PosiPen?

Compared with the PosiPen, the PosiTest provides superior accuracy and improved ease-of-use by using a large dial to increase spring pressure, and by holding the displayed gage reading after being removed from the coated part. The PosiPen is ideal for small, hot or hard-to-reach surfaces.

Is the PosiTest affected by the roughness of the steel substrate below the coating?

All coating thickness gages are influenced to some degree by substrate roughness. It is generally accepted that coating thickness should be measured from the highest ‘peaks’ in the rough surface thus ensuring they are covered by the protective coating. However, coating thickness gages will instead measure the coating thickness from the effective magnetic surface, which is located somewhere between the highest peaks and deepest valleys of the profile.

To compensate for the influence of substrate conditions (including roughness), measure the uncoated substrate/part at a number of spots to obtain a representative average value. This average value is called the “base metal reading” or “BMR”. Subtract the BMR from subsequent coating thickness measurements to obtain the thickness of the coating over the ‘peaks’ of the rough surface.

Can the PosiTest measure nickel on steel?

Yes, but it depends upon the particular type of nickel coating that has been applied to the steel.

When nickel plating is deposited by a process of electrolysis (employing an electric current in the nickel bath), the resultant coating – commonly called “e-nickel” – is always conductive and magnetic to some degree and cannot be accurately measured by our gages when applied to ferrous or non-ferrous metals.

Electroless nickel coatings are deposited by an autocatalytic process which does not involve the addition of an electric current. If the nickel bath in this process contains a minimum concentration of ~8% phosphorus, the resulting nickel plating is effectively non-magnetic and its thickness can be accurately measured on ferrous steel with a magnetic principle coating thickness gage such as the PosiTest.

Does the PosiTest measure on hot surfaces?

The operating temperature range of the PosiTest depends on the use case. The first case is where the measurement surface and the gage are both at the same temperature;  in this case the operating range would be -10°C to 60°C (14°F to 140°F). The other case is where the PosiTest is at a “normal” room temperature but the measurement sample may be at a different temperature. In this case the PosiTest can measure on surfaces with temperatures ranging from -50°C to 100°C (-58°F to 212°F), so long as the instrument itself is kept within its operating range.

Can the PosiTest be used underwater?

Yes. The PosiTest features corrosion-resistant brass construction and can be immersed in fresh or saltwater. When used in saltwater, it is recommended to rinse with freshwater after use.

Can the PosiTest be adjusted?

While the PosiTest can be adjusted, this is not recommended for most applications. The permanent rare-earth magnet eliminates the need for adjustment, unlike other mechanical instruments. If a PosiTest is not functioning properly in accordance with NIST / PTB calibration standards we recommend the Gage be returned to us for a no-cost evaluation. Opening the PosiTest for purposes of cleaning, re-balancing and recalibration is not recommended.

Does the PosiTest measure on non-ferrous metals, like aluminum?

No. As a magnetic principle instrument, the PosiTest will measure the thickness of non-magnetic coatings applied to ferrous metals. Our popular PosiTest DFT Combo and powerful PosiTector 6000 N gage models are ideal for measuring the thickness of paint, anodize and other non-conductive coatings applied to non-ferrous metals.

Is the PosiTest ‘automatic’?

The PosiTest is a simple, manually-operated coating thickness gage. The GO/NO-GO button can be preset for taking rapid, accurate measurements.

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Is the PosiTector 6000 calibrated at the factory?

PosiTector 6000 instruments arrive fully calibrated and include a Long-Form Certificate of Calibration traceable to NIST or PTB. The Certificate of Calibration documents actual readings taken by your instrument at our calibration laboratory, on standards traceable to a national metrology institute. Beware of ‘Certificates’ or ‘Certificates of Conformance’ offered by competitors. These typically do not include actual instrument readings, and are often insufficient to meet common quality requirements.

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Does the PosiTector 6000 need to be ‘calibrated’ or ‘adjusted prior’ prior to use? Do I need to perform a two-point adjustment prior to measuring?

The innovative probe technology and factory calibration in the PosiTector 6000 means that it arrives ready-to-measure — usually there is no need to perform a two-point calibration adjustment. Ruby or alumina probe tips on standard probe models eliminate wear, meaning that the factory calibration is maintained throughout the lifetime of the probe. Whether out of the box or after years of use, PosiTector 6000 will continue to provide accurate results.

For highest confidence and best measurement accuracy, observe our “golden rule” — simply check ZERO (or the known thickness of a shim) on the uncoated part, adjust if necessary, and then measure the coated part. This ensures that the probe is properly adjusted for substrate characteristics including mass, metallurgy, curvature, temperature and roughness.

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Do your instruments require any formal training for use? Do you offer ‘demo’ models?

No. Our instruments are designed for simple operation, feature easy-to-use menus, both full and quick instruction manuals, and helpful videos. In lieu of demonstration models, we provide unlimited technical support via telephone and/or email, and a limited 30-day money back guarantee.

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How often should the PosiTector 6000 be recalibrated?

PosiTector 6000 probes include a Certificate of Calibration with no expiry or end date. They have no shelf life, therefore the length of time in the field is not a good indicator for recalibration intervals. Many organizations with quality programs and recertification programs require annual recalibrations, and this is a good starting point for most users. DeFelsko recommends that customers establish calibration intervals based upon their own experience and work environment. Based on our product knowledge, data and customer feedback, a one year calibration interval from the date the instrument was placed in service is a good starting point.

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What can the PosiTector 6000 measure?

PosiTector 6000 probes have different capabilities depending on the model.

  • ‘Ferrous’ model probes (order code beginning in ‘F’ ex. FS1) can measure non-magnetic coatings applied to ferrous (magnetic) metals, typically carbon steel.
  • ‘Non-ferrous’ model probes (order code beginning in ‘N’ ex. NRS3) can measure non-conductive coatings applied to non-ferrous metals.
  • ‘Combination model probes (order code beginning in ‘FN’ ex. FNTS1) can measure non-magnetic coatings applied to ferrous (magnetic) metals, AND non-conductive coatings applied to non-ferrous metals
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Is the PosiTector 6000 affected by the surface roughness (profile) of the metal substrate below the coating?

All coating thickness gages are influenced to some degree by substrate roughness, as shown in the below image. It is generally accepted that coating thickness should be measured from the highest ‘peaks’ in the rough surface thus ensuring they are covered by the protective coating. However, coating thickness gages will instead measure the coating thickness from the ‘effective magnetic plane, which is located somewhere between the highest peaks and deepest valleys of the profile.

SSPC-PA 2 proposes several solutions depending upon the instrument type and the particular situation. Similar methods are suggested by ASTM D7091 and ISO 19840.

One option is to verify the gage reads zero on the uncoated steel substrate, and adjust to zero if necessary. This is a popular solution when the metal surface is relatively smooth.

Since it is difficult to ensure that the probe tip is sitting on the highest peaks of the surface profile, another option is to place a plastic shim of a known thickness that is close to the expected thickness of the applied coating between the probe and substrate and adjust to the stated thickness of the shim- referred to as a 1-point adjustment. The plastic shim sits on the peaks of the surface profile over a greater area than the probe tip, ensuring that the adjustment is being taken ‘over the peaks’. This best simulates a coating covering the peaks of the surface profile.

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Can the PosiTector 6000 measure coatings on stainless steel?

"Stainless steel" is a term used to generally categorize a wide variety of corrosion and heat-resistant alloys. In specific terms of metallurgy, a “stainless steel” is any iron-based alloy containing a minimum of 10.5% chromium content by mass. Some stainless steel alloys have a relatively low magnetic response (often called “partially/weakly magnetic”). Others have no magnetic response whatsoever, and some possess a ferromagnetic response similar to carbon steel.

The PosiTector 6000 is uniquely able to measure partially magnetic stainless steel alloys, an application that is challenging for many competitive instruments. PosiTector 6000 FN (combination ferrous/non-ferrous) probe models can often measure consistently on partially magnetic substrates with a simple Zero adjustment. For more challenging applications, the “N-Lock” measurement mode permits accurate measurement of non-conductive coatings applied to partially magnetic substrates.

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Can the PosiTector 6000 measure coatings on hot surfaces?

The PosiTector 6000 FXS and FHXS Xtreme probes are ideal for measuring coating thickness on hot and/or rough surfaces (250°C, 500°F maximum). All PosiTector 6000 probe are capable of measuring on hot surfaces. Standard probe models can operate at environments up to 50˚C (120˚F). However, if the probe is lifted clear of the surface as soon as a reading is taken and is allowed to cool, measurements can be taken at higher temperatures. Simply ensure that the probe remains at a temperature of less than 50˚C (120˚F), and cool enough to handle with an unprotected hand.

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What is the minimum part size required to take a reading?

To ensure a part’s dimensions are suitable for a PosiTector 6000 probe, simply check ZERO on the uncoated part and adjust if necessary. Verify accuracy by measuring a plastic shim placed on the uncoated part. If the measurement is within the combined tolerances of the shim and probe, the probe is suitable for measuring the coated part.

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Can the PosiTector 6000 be used underwater?

While the PosiTector gage body and probe connector are not suitable for immersion in water, PosiTector 6000 regular cabled probes are hermetically sealed and ideal for underwater use. Extended cables are available (up to 75 m/250 ft) for underwater or remote measuring.

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Is the PosiTector 6000 intrinsically safe?

While the PosiTector 6000 is not designed as an intrinsically safe device, our PosiTest mechanical gages are ideal for measuring coating thickness in hazardous operating environments.

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Can the PosiTector 6000 measure nickel on steel?

Yes, but it depends upon the particular type of nickel coating that has been applied to the steel.

  • ‍When nickel plating is deposited by a process of electrolysis (employing an electric current in the nickel bath), the resultant coating – commonly called “e-nickel” – is always conductive and magnetic to some degree and cannot be accurately measured by our gages when applied to ferrous or non-ferrous metals.
  • Electroless nickel coatings are deposited by an autocatalytic process which does not involve the addition of an electric current. If the nickel bath in this process contains a minimum concentration of ~8% phosphorus, the resulting nickel plating is effectively non-magnetic and its thickness can be accurately measured on ferrous steel with a magnetic principle coating thickness gage such as a PosiTector 6000 F model.

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