Restoring - General discussions that span across many different groups of years and models > Processes, Products & Techniques

Zinc Plating -

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jwc66k:
I picked up some parts I had zinc plated a little while ago, and got a relatively new finish (two years for this plate shop) on some items. It's referred to as "dull zinc", as opposed to "clear zinc". A comparison picture of two trunk strikers shows the difference. The dull finish replicates cadmium plating, aka soft silver, Ford finish code -S7. Finish code -S8 does not specify "chromate", see finish code -S9 and others, or dichromate, see -S35 and others. However, a chromate treatment does provide additional corrosion protection and is a good surface preparation for painting. Specifying zinc dichromate may result in a yellowish tint per its industry standards. My plater, Bob (a long time Silicon Valley business owner, over 50 years) recommends to get the correct zinc finish, use the terms "clear", "dull" or "gold". He also does black zinc but says that process is more expensive, higher materials and labor costs.
Jim

CharlesTurner:
Considering Cadmium plating is probably becoming obsolete, it seems like the only alternative.  Here are some parts that I had Cad plated about 10 years back... more silvery looking.  Unlike zinc plating, I had found Cad to be relatively consistent in the final finish.  Zinc could vary with either shiny silver or silver with bluish hues.

Bob Gaines:
With my home plating set up it is easy to get the dull zinc. Sometimes too easy as in when you want it shiny it comes out dull. You have to have the correct brightener agent added to the plating brew for it to come out shiny.

J_Speegle:

--- Quote from: jwc66k on July 27, 2017, 03:03:58 PM ---.................. My plater, Bob (a long time Silicon Valley business owner, over 50 years) recommends to get the correct zinc finish, use the terms "clear", "dull" or "gold". He also does black zinc but says that process is more expensive, higher materials and labor costs.
Jim

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Yes the terms seem to be the challenge at times depending on where you are located. Suggest that anyone having someone do this for them to ask to see samples first and then confirm what the platters terms are for each so that you get what you expected to get. Also on more recent batches have found that allot fo local platers are now doing parts in baskets  rather than manually tying each part along a strand of bailing wire as was typical years ago. Often could save a few bucks if you just told the platter to leave them on the string and you would remove them. Also found some batches benefited by coating them in some oil to deduct the chance of oxidation over time 

Just what has worked for me

jwc66k:

--- Quote from: J_Speegle on July 27, 2017, 06:03:27 PM ---Also on more recent batches have found that allot fo local platers are now doing parts in baskets  rather than manually tying each part along a strand of bailing wire as was typical years ago.

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The "basket" process does not always give good results as it is "static", not moving. Electrical continuity is required to get an even look, and even more important, a consistent thickness (it's not much, 0.00015 to 0.0002). A more common process is "tumble plating". It has its drawbacks as scratches may develop and parts sometimes get lost in the tumbler. My plater currently wires most everything, but that process occasionally leaves a "bald spot" where the wire was attached. Almost all thicknesses are measured by elapsed time by a lot of platers along with voltages, temperature and acidity of the bath.
Back when I worked for a living, I preferred to have the tumble process used and specified as such. That was for very large quantities of the same small part. Times have changed.

--- Quote from: J_Speegle on July 27, 2017, 06:03:27 PM ---Also foudn some batches benefited by coating them in some oil to deduct the chance of oxidation over time 

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Before or after plating? I send all my parts bead blasted and dry (the current humidity is 33 percent).
Jim

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