I am facing one problem in silver plating Ours is a conventional silver plating bath contains 150g/l kcn & 25 g/l ag we have improved our acidconc of acid cleaning to 25%.Alkaline cleaning bath conc is also increased to8%.still we are getting yellow patches Our process sequence is as fallows hot soak(5min),anodic(3min)rinsing,acid cleaning,rinse ,copper plating(rochelle),cyanide dip,silver strike , silver plating ,rinse ,passivation (chrome) rinse hot rinse.
Please tell what could be the reasons. also please write us ideal conc of plating bath & cleaning conc to get quality finish.
A P Barve.Avinash P Barve
First you have to check your brighteners if you don't use you must.
You can give the pice a niquel coated after the copper
The ideal bath of silver is 125 to 150 gr/L. kcm 26 to 32gr/L. Ag
Please if you have any result, post it.
You might want to try turning off the heat on your final rinse. On matte finish cyanide silver this is a must to eliminate yellowing. It takes longer to dry the parts, but the appearance is much better. Also, are your spots appearing after you handle them. This can also be a trouble spot.Phil Pace
- Tulsa, Oklahoma
DEAR SIR, ADVISED PL TO USE BEST QUALITY OF brighteners AND MAINTAIN PROPER CONCENTRATION OF brighteners. UTILISATION SYSTEM OF CYANIDE WILL SOLVE YOUR PROBLEM.SHAH JANAT
AHMEDABAD/ GUJ/ INDIA
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