It has been some time since I used Plus-X at all, but I don't recall any problem getting it to stain in PMK. With variable contrast papers, a blue cast to the emulsion might inhibit yellow light slightly, but unless the blue color was particularly strong my guess is it wouldn't inhibit enough to make a discernable difference.(posted 8410 days ago)I'd be curious to hear other workers' comments on Plus-X in PMK.