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Sudden High pH in E-Coat Bath

My e-coat bath jumped from a PH 6.1 TO 6.7 in one day. My DI water appears good. My paint supplier is performing bacteria test. Any other ideas?

Chet Sweatman
Paint Manager - Georgia
September 19, 2008

Hi Chet,
Has there been a change in the appearance or thickness of the coating or opacity of the bath? If not I would suspect the pH meter. ED resins can cause severe fouling of pH electrodes and subsequent significant errors.

If the coating quality/properties are unchanged, I suspect the pH meter. Electrodes are easily contaminated and give errors.

Harry Parkes
- Birmingham, UK
September 24, 2008

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