Metal finishing Q&As since 1989
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How can I avoid over phosphating our parts?
I would like to know if there is any way to keep from over phosphating parts. I keep coming up with the violet gold color, which means I am over phosphating parts. What can I do to keep this from happening. Can I change the pH of the phosphate or rinse tanks?
Thanks,
quality engineer - KY
2007
From the description of colour ,I think you are talking about Iron Phosphating.Gold colour might be because of flash rusting of components.It all depends on ionic balance of the bath.Uniform coating will not give gold colour.Over phosphating should give more coating weight.
Call your chemical supplier and discuss.
surface coatings - Mumbai, India
2007
2007
Hi CM,
Not sure what you mean by over-phosphating. If you think that you are depositing too much coating, then you can reduce it most easily by reducing the concentration of the phosphating product or reducing the temperature of the bath.
You can adjust the pH of your phosphating bath, but that may cause more problems than it will solve. Your supplier should be able to tell you the optimal pH range for the product. It is important to keep the bath in this range.
- Naperville, Illinois
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