Professional Detailing2 min read

Doubling Weathering Intensity Does Not Automatically Halve the Required Test Time

Increasing irradiance and reducing exposure time by the same factor does not automatically produce an equivalent coating result. A shorter, more intense test needs a technical justification appropriate to the material and failure mechanism.

Updated · NANOLAB Knowledge

The key distinction

Q-Lab cautions against assuming simple reciprocity in weathering. The practical consequence is that a laboratory schedule cannot be compressed solely by keeping an energy calculation constant. Other exposure conditions and material responses remain relevant, so any proposed change should be reviewed as a change to the test method.

Practical checks

  1. Ask why the revised intensity is appropriate for the material and decision.
  2. Keep the original and modified exposure conditions separately identified.
  3. Require the laboratory to explain what comparison the revised test can and cannot support.

Example

Illustrative example: a product launch is approaching and a buyer asks to double the exposure intensity to finish in half the time. Matching a calculated dose is not sufficient evidence that the new schedule reproduces the original outcome. The project needs a justified method or a narrower claim.

Scope and limits

Do not present an abbreviated screening exercise as completion of an unchanged qualification programme. This guide does not prescribe a replacement schedule. The responsible laboratory should evaluate the proposed acceleration and document the limitations before results become purchasing or marketing evidence.

Related guidance

Technical references: Q-Lab: The myth of reciprocity. These sources describe their stated methods or products; they do not certify NANOLAB products or establish compatibility with an unlisted surface.

Ask NANOLAB about the exact product and intended use. Use the current product documentation for formulation-specific instructions.

Professional Detailing2 min read

Weathering Spectrum Changes: Equal Intensity Does Not Mean Equal Exposure

Two weathering exposures can have similar reported intensity while differing in the wavelengths reaching the sample. A coating comparison should retain the spectral information relevant to the method instead of treating one intensity number as the complete exposure description.