plating, anodizing, & finishing Q&As since 1989
Aging effects on electropolished stainless steel?
I am working on a project where I am passing IR light down a stainless steel tube. In order to maximize the light transfer, the SS tube is electropolished and then gold plated. So far, I have had good success in my application. My question is one that affects production. We would like to buy the SS tube in 1000 ft increments, however, we will not use it all immediately. My question is how will the passage of time affect the electroplated tube? If the electropolished tube has to sit on a shelf for 6 months or a year before gold plating will the finish degrade? Is there a possibility of something happening to the surface that will cause a problem with the gold plating process? Are there any precautions that I should take that will prolong the shelf life or ward off any problems that I might otherwise incur?
- Newnan, Georgia
As long as the tube is stored in a conditioned space (heated in the winter and air-conditioned in the summer)it should be fine. Condensation is your biggest concern.
The passive film on the SS tube must be removed before gold plating to ensure good adhesion so a little discoloration of the film should not hurt the final product. Make sure that the gold is thick enough to stay bright (migration of the elements/metals in the SS might dull the surface with time).
Regards,Fred Mueller, CEF
- Royersford, Pennsylvania
I am working on a project that uses a photoelectric sensor to sense the presence of a particular part in the system. The sensor beam lands on one of the surface of the part being sensed. This part is made of plastic and is prone to scratches. The sensor gives wield readings when it hits the scratches, so I decided to add a steel plate on the surface. The surrounding environment is highly corrosive (this steel plate is going to be very close to the sulphuric acid bath), so I decided to use electropolished stainless steel. But when electropolished, the surface becomes so reflective that the sensor blanks out. It is unable to detect the distance. Is there a coating that I can put on the plate such that it serves both the purposes, it is electropolished to sustain in the acid/corrosive environment and the surface is opaque so that the sensor works fine?
- Portland, Oregon