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DeFelsko PosiTest

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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

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
  • 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

 

PosiTester FM / F / GM / G
FM PosiTest Instrument with FM Scale
F PosiTest Instrument with F Scale
GM PosiTest Instrument with GM Scale
G PosiTest Instrument with G Scale

Available PosiTest models

PosiTest FM PosiTest F PosiTest GM PosiTest G
PosiTest FM - Ideal for measuring coating thickness of hot dip galvanizing, hard chrome metalizing, paint, enamel, plastic coatings on steel. (mils) PosiTest F - Ideal for measuring coating thickness of hot dip galvanizing, hard chrome metalizing, paint, enamel, plastic coatings on steel. (microns) PosiTest GM - Ideal for measuring coating thickness of electroplating, thin paint films, phosphating on steel. (mils) PosiTest G - Ideal for measuring coating thickness of electroplating, thin paint films, phosphating on steel. (microns)
Application: Application: Application: Application:
Hot dip galvanizing, hard chrome metalizing, paint, enamel, plastic coatings on steel. Hot dip galvanizing, hard chrome metalizing, paint, enamel, plastic coatings on steel. Electroplating, thin paint films,  phosphating on steel. Electroplating, thin paint films,  phosphating on steel.
Scale FM Scale F Scale GM Scale G
0-80 mils 0-2000 µm 0-8 mils 0-200 µm
Tolerance: Tolerance: Tolerance: Tolerance:
+ / - 0.2 mils up to 4 mils + / - 5 percent of the reading over 4 mils + / - 5 µm up to 100 µm + / - 5 percent of the reading over 100 µm + / - 0.04 mils up to 0.8 mils + / - 5 percent of the reading over 0.8 mils + / - 1 µm up to 20 µm + / - 5 percent of the reading over 20 µm

 

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 percent 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 deg C to 60 deg C (14 deg F to 140 deg 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 deg C to 100 deg C (-58 deg F to 212 deg 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.

 

Magnetic Pull-Off

Magnetic pull-off gages use a permanent magnet, a calibrated spring, and a graduated scale. The attraction between the magnet and magnetic steel pulls the two together. As the coating thickness separating the two increases, it becomes easier to pull the magnet away. Coating thickness is determined by measuring this pull-off force. Thinner coatings will have stronger magnetic attraction while thicker films will have comparatively less magnetic attraction. Testing with magnetic gages is sensitive to surface roughness, curvature, substrate thickness, and the make up of the metal alloy.

Magnetic pull-off gages are rugged, simple, inexpensive, portable, and usually do not require any calibration adjustment. They are a good, low-cost alternative in situations where quality goals require only a few readings during production.

Rollback dial models (PosiTest shown in Fig 2) are the most common form of magnetic pull-off gage. A magnet is attached to one end of a pivoting balanced arm and connected to a calibrated hairspring. By rotating the dial with a finger, the spring increases the force on the magnet and pulls it from the surface. These gages are easy to use and have a balanced arm that allows them to work in any position, independent of gravity. They are safe in explosive environments and are commonly used by painting contractors and small powder coating operations. Typical tolerance is + 5 percent.

Coating Thickness Measurement

Fig. 2. Roll-back dial magnetic pull-off thickness gauge.

 

FM
POSITEST FM (0-80 MILS) - COATING THICKNESS GAGE
CALL 800-458-3687 X1 FOR ANY BROTHER-IN-LAW SPECIALS ON THIS DEFELSKO ITEM
Mfg. item #: FM
DEFFM
Free 2nd Day AIr for DEFELSCO orders over $599!1047
$350.00

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F
POSITEST F (0-2000 MICRONS) - COATING THICKNESS GAGE
CALL 800-458-3687 X1 FOR ANY BROTHER-IN-LAW SPECIALS ON THIS DEFELSKO ITEM
Mfg. item #: F
DEFF
Free 2nd Day AIr for DEFELSCO orders over $599!1047
$350.00

6
GM
POSITEST GM (0-8 MILS) - COATING THICKNESS GAGE
CALL 800-458-3687 X1 FOR ANY BROTHER-IN-LAW SPECIALS ON THIS DEFELSKO ITEM
Mfg. item #: GM
DEFGM
Free 2nd Day AIr for DEFELSCO orders over $599!1047
$350.00

6
G
POSITEST G (0-200 MICRONS) - COATING THICKNESS GAGE
CALL 800-458-3687 X1 FOR ANY BROTHER-IN-LAW SPECIALS ON THIS DEFELSKO ITEM
Mfg. item #: G
DEFG
Free 2nd Day AIr for DEFELSCO orders over $599!1047
$350.00

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