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Determination of Film Thickness BS EN ISO 2808: BS 3900-C5

Scope and Field of Application

BS EN ISO 2808 and BS 3900-C5 are alternative names for a number of methods that are applicable to the measurement of the thickness of both wet and dry organic coatings. None of the methods are suitable for measuring metallic coatings but some can be adapted for the measurement of detached organic films. The standard also defines a number of terms concerning the determination of film thickness.

There are no pass/fail criteria defined in the standard. This is a matter of agreement between the parties concerned.

The actual standard is a copyright-protected document and we are not able to provide you with copies. If required however, you can easily obtain copies from the British Standards Institution.

 

Summary of Methods

Listed below are those methods which appear in the standard and which we can carry out:-

Type of Film	Technique	Use on Site?	Advantages	Limitations
Wet	Comb Gauge	Yes	Cheap. Simple to use	Not very accurate
Wet	Wheel Gauge	Yes	Cheap. Simple to use	Not very accurate
Wet or Dry	Gravimetric	No	Does not require special equipment. Useful for soft films	Not very accurate
Dry	Micrometer	Yes	Fairly cheap	Destructive. Only suitable for smooth flat substrates (or wire). Need to be able to remove coating.
Dry	Microscope	Yes	Can be very accurate under laboratory conditions. Fairly cheap and simple when used in the form of a Paint Inspection Gauge (PIG).	Destructive
Dry	Magnetic Induction Meter	Yes	Non-destructive. Can make numerous measurements over a short time period. Can be used with blast-cleaned steel substrate.	Expensive. Needs magnetic metallic substrate.
Dry	Eddy Current Meter	Yes	Non-destructive. Can make numerous measurements over a short time period.	Expensive. Needs non-conductive coating on non-magnetic metallic substrate.

We will be pleased to advise on the most appropriate method to use with your samples. It is important to realise however that there are some samples for which it is impossible to obtain a realistic measure of the film thickness. Examples include highly textured coatings, coatings on uneven substrates and coating applied to substrates that are porous.

 

Sample Requirements

Detached paint flakes should be at least as large as your thumb nail and should include all layers from the one adjacent to the substrate up to the top coat. Our requirements when dealing with coated substrates vary depending on the method to be used and we will be pleased to discuss this with you.

 

Accreditation

PRA is accredited to ISO 17025 by the United Kingdom Accreditation Service (UKAS) to carry out this test.

 

Please contact Peter Collins for further details.

 

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