I have ran into similar issues quite some time back. My issue was obviously connected to the design and my racking used. I had stainless Steel racks that either had a "galvanic" condition taking place or some sort of thermal absorption into the rack from the signal layer. The whole thing was strange because some jobs had it and some didn't. (NahNu NahNu????) Anyways....We increased the agitation in the oxide bath to something from nothing and plastisol coated our racks and the problem went away. (Poooof!) Good Luck! Stay in touch! [log in to unmask] ______________________________ Reply Separator _________________________________ Subject: Periodic Problems With Oxiding Author: [log in to unmask] at SMTPLINK-HADCO Date: 11/27/95 3:49 AM Does anybody have a definitive Cause and Corrective Action for a problem that seems to occue infrequently with oxiding? Specifically a detail with a power or ground plane and a signal layer opposite will oxide fine on the power/ground side, but will occasionally oxide incompletely on the other side. I've always thought it was basically a cleaning problem, and I know it has occurred on a variety of coppers and substrates. But on occasion it has been very persistent, unable to be improved by strip and re-oxide for example. Very frustrating to the PWB producer and both the laminator and the chemical supplier get accused of having something wrong with their products. Any ideas?