Black spot observed on electroless nickel plated steel

A. Hi Mahendra. Every possible defect has multiple possible causes, so answers offered before any data has been supplied can be like shooting off a scattergun and suggesting that you follow each pellet as a possibility.

Instead, please give us some basic data: do these black spots appear on every piece you produce and they always have and they uniformly cover the articles? ... or can you tell us that they recently started, or effect only one particular component, or only one specific area, etc.? Have you examined the components before plating and assured yourself that they are free of pits and problems?

Is this a commercial electroless nickel plating bath from a recognized supplier, and have all parameters been rigorously checked and found to be within the range specified on technical data sheet? Larry Durney's caution is always make sure to "Obey the Letter of the Law" before attempting any troubleshooting.

Please send pics of the defect to mooney@finishing.com for posting here. A picture is worth a thousand words, especially when describing a defect. Thanks!

Regards,