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Sparks on bulk of metallic pieces during CED

In our plant, we are using Cathodic Electro Deposition (CED) to paint small steel parts. We place all the pieces in bulk, in a bucket.
On some pieces, there is a little round hole where the steel melted. This seems to be caused by a spark.
We tested in laboratory that such a spark occurs when one of the piece is "floating", thus getting to the 300V of the bath. If a movement cause this part to touch the bulk of pieces linked to 0V, this create a spark.
This phenomenon seems to happen more often at the end of the cycle, when there is more paint on the parts, causing them to be floating.
Is there a good way to eliminate those sparks?

Michel Dion
Automation engineer - Quebec, Canada
November 16, 2009