The idea of etching PET with an alkali metal hydroxide seems common enough in the patent literature and there is also mention of resin coating and, of course, corona discharge. The corona discharge method appears to be considered the state of the art for maybe the past 20 or so years, likely because it may be more controllable and easily able to be done as an in-line process step without chemicals.

Tonight, I did try a quick experiment with a 10% solution of sodium hydroxide in water, which brings the first problem: PET is hydrophobic so the solution runs right off. (duh!) What's an appropriate solvent for the NaOH? Perhaps ethanol or methanol? Would a wetting agent like photo-flo help? There were some references to ethylene glycol as a solvent as well.

-- Jason