It is important that the supporting window of the XRF sample cup is transparent to all of the signals generated by the analyzes of interest, and that it is also chemically compatible with the samples.

At present, a wide range of window materials are available in many different thicknesses to contain the sample, such as Kapton, polyproylene, and Mylar®.

XRF Film Materials


Kapton is a tough polymide and has an orange/yellow color. It is stable across a wide range of temperatures and often has a thickness of 7.5 µm. While Kapton can support most samples, it is particularly affected by strong basic solutions. ASTM methods for analyzing sulfur in diesel stipulate the use of Etnom® or Kapton only.


Polypropylene is a thin-film plastic material with a large %-transmittance for light and heavy elements, even when in low concentrations. Thickness is typically 6 or 12 µm. This slightly thicker film provides additional security against tearing. Although polypropylene has better transmission than the Mylar® film, it has a lower tensile strength.


Mylar® is suitable for many routine XRF analyzes and is often used for detecting sulfur in oils, fuels, lubricants (but not diesel – see above). It is also tough and has a high tensile strength that is resistant to all liquid samples tearing through the film. One weakness of Mylar® is that it is not chemically compatible with aliphatic alcohols, esters, ketones, or aromatics. Mylar® is a trademark of E.I.DuPont de Nemours, Inc.


  • Self-adhesive protective films
  • Pre-perforated rolls available
  • Continuous rolls available
  • Pre-cut circles available
  • A wide range of materials and sizes available

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