PE often has a plasticized chemical residue left on it from the etching process. The residue is similar to a light clear coat, and can sometimes interfere with CA adhesion. Acetone, lacquer thinner, or a light sanding will remove it. You can also remove it by annealing the PE over a low flame, which has the added benefit of making PE easier to bend. However, use caution, as too much heat can melt or deform the metal part. I always clean my PE parts with lacquer thinner after annealing if I use a candle flame to anneal, as it produces soot. More often, I use a Bernz-O-Matic torch to anneal with, but I’m very careful to keep the flame on low, and just pass the PE quickly through the flame. But you don’t want to do this with really tiny PE parts.
VR, Russ