With reference to Air in the Solution , an overlooked area is the circulation systems. Make sure that the suction side of the pump has no leaks, and for best results put the filtration on the pressure side of the pump. this way you can eliminate cavitation of the impeller by providing a constant back pressure on the impeller. Also don't forget to pre-wet your filters to remove most of the air from them before you install them. With todays fine feature technology I don't recommend increasing the filter rating much beyond 50 micron absolute . ---------- From: Gwerder Lorenz To: [log in to unmask] Subject: [TN] Pitting Date: Saturday, April 03, 1999 3:07AM We are a PCB manufacturer and are currently dealing with the "PITTING" problem. Small holes, craters in the electrolitic copper. Is there any acceptability guideline corresponding this problem. I did not find it in the IPC-A-600. Thanks for your help Lorenz Gwerder [log in to unmask] <mailto:[log in to unmask]> www.photochemie.ch <http://www.photochemie.ch> ################################################################ TechNet E-Mail Forum provided as a free service by IPC using LISTSERV 1.8c ################################################################ To subscribe/unsubscribe, send a message to [log in to unmask] with following text in the body: To subscribe: SUBSCRIBE TechNet <your full name> To unsubscribe: SIGNOFF TechNet ################################################################ Please visit IPC's web site (http://www.ipc.org) "On-Line Services" section for additional information. For technical support contact Hugo Scaramuzza at [log in to unmask] or 847-509-9700 ext.312 ################################################################