Letter 20080

Pink spotting on brass parts  

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We are experiencing pink spotting on our brass parts after annealing and oven exposure. Prior to this they are being formed with two different draw lubes, washed with hot city water(1.0 ppm free chlorine prior to heating) and eventually annealed and oven baked. Small amounts of draw lube sometimes make it past the hot water rinse, but from my past experience something acidic usually is needed to produce the pink spotting, so I doubt the drawing compounds are the problem. Can the free chlorine from the city water be the culprit? Any suggestions?

Dan Buehler
- Antigo, WI

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