Adhesion failure does not always come from the monomer. Pigmented coatings, thick films, shadowed areas and dark substrates can absorb or block UV, leaving the bottom layer undercured.
Record lamp type, wavelength, power, line speed, accumulated dose and number of passes. If the LED wavelength does not match the photoinitiator absorption, surface cure may look normal while depth cure remains incomplete.
First fix film thickness and dose, compare blank with monomer, then run a dose ladder. Failure only at low dose indicates a narrow process window; failure at high dose points back to interface or formulation compatibility.
Note: record dose with a UV radiometer; lamp power alone is not sufficient.
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