Extech Instruments NON-DISPLAY PORTABLE Specifications download pdf (Page 10)

CG204-EU-EN v2.2 8/13

CalibratingforShot‐blastedsurfaces

Thephysicalnatureofshot‐blastedsurfacesresultsinhigherthannormalcoatingthicknessreadings.The

meanthicknessoverthepeakscanbedeterminedasfollows:

1. Themetershouldbecalibratedaccordingtothecalibrationinstructions.Useasmoothcalibration

samplewiththesamecurvatureradiusandthesamesubstrate

asthedevicetobetested.

2. Takeapprox.10readingsontheuncoated,shot‐blastedsampletoproducethemeanvalueXo.

3. Takeanadditional10readingsonthecoated,shotblastedtestsampletoproducethemeanvalueXm

4. Thedifferencebetweenthetwomeanvalues

isthemeancoatingthicknessXeffoverthepeaks.The

greaterstandarddeviation‘S’ofthetwovaluesXmandXoshouldalsobetakenintoconsideration:Xeff

=(Xm‐Xo)±S



NOTE:Forcoatingsthickerthan300µm,theinfluenceofroughnessgenerallyisofnoimportanceand

thereforeitisnotnecessarytoapplytheabovecalibrationmethods.

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Extech Instruments NON-DISPLAY PORTABLE Specifications Page 10