A new method of monitoring the cure of resins in paper laminates is described. Samples of high pressure decorative phenolic laminates, with degrees of cure ranging from 75 to 100 per cent, have been scanned with 3 cm microwaves. It has been shown that the amplitude of through-transmitted waves decreases linearly with increasing cure, the correlation being such that the degree of cure of a given sample should be obtainable virtually instantaneously to a standard deviation of ± 2 per cent.