The authoritative public forum
  for Metal Finishing since 1989
  

  -----

Electrodeposit Zinc Plating Affecting Zinc Phosphating

2006

Hi,

I am a design engineer in the UK for a manufacturer of vibration isolation mounts, bearings, etc. Most of our products are either zinc phosphated on site or electrodeposit zinc plated at a sub-contractor.
My question is: supposing, due to the customers requirement, there are surfaces of an item that have been zinc phosphated on site, then the remaining surfaces need to be zinc plated; if masking of the zinc phosphated surfaces is impractical, what happens to these surfaces when the item is zinc plated?

Regards,

Conrad Hextall

---

If not masked, the phosphate will be degraded in at least the caustic cleaner and the acid etch. I would also expect some spot plating of zinc in those areas. No where enough information for anyone to properly answer your question.
One way to find out is to plate some test parts that you can rework.

James Watts
Navarre, Florida
2006

Conrad, the typical zinc plating process uses an alkaline cleaning and an acid activation stage. Both of these processes are capable of stripping the zinc phosphate coating off the parts. As result, after the plating process, you will no longer have any zinc phosphate present and the zinc phosphate will not interfere with the plating process.

Roy Nuss

2006