A Slight Scientific Approach

[intern21]

So here is an intersting one:

I am currently an intern working for a company that deals with EDM wire. We have some wire samples that have an outside coating we cannot see well when we use the SEM (scanning electron microscope). My supervisor suggested we plate the samples with nickel so when we prep the samples, we don't accidently grind off the outside layer.

These samples are brass wires with a high concentration of zinc on the outside (so I have been told). I have purchased the Mini Electroless Ni plating kit and have done initial platings samples. Instead of the .001"/hr I am supposed to get I am getting .0001"/hr (I have access to micrometers). How can this be fixed? Do I have zinc contamination? The samples are very small.

I should say that the wire samples are suspended from galvinized steel wire with most of the zinc sanded off (I think). It is hard to tell of the wire samples pass the water break test, due to how thin they are.

Also, will I need to use new steel wire everytime I need to plate a different wire sample? Does the Ni that plates to the steel affect its "activating" properties?

Also, I have stripped the zinc from the sopporting wire using muriatic acid and then plated directly on the supporting wire. That got me the .001"/hr that the manual states I should be getting. The next test I ran, though, with the stripped wire supporting the sample, I still only got .0001"/hr. I could really use some experienced help here.

Finally, what color is the final solution supposed to be after the final preparation for disposal? I still have a blue solution with what looks like fine white solids. The manual mentioned "water white".

[CarWiz]

I suspect that your measurement is the net of the Ni plating and the striping of the zinc coating on the EDM wire. The EN plating solution will strip (dissolve) zinc to the base metal before plating will occur. You can't plate directly over zinc. If you subject the solution to excessive zinc, it will become contaminated and lead to spotting and uneven plating.

You should follow the directions for "plate-out" before disposing of the batch. Simply adding the disposal chemical does not render the solution disposable. You need to insert the steel wool pad in the solution to "plate-out" the nickel remaining in the batch.

As a side bar: You should be able to "recharge" an existing batch using the "Credits" formula up to about 10 times. It's not necessary to mix a new batch for each use. If you keep accurate records of the credits, the solution can be reused or stored until needed.