Little bit of Zinc plating during lockdown

Had a new zinc plating kit sitting in the garage now for around eight years unused, I've been cleaning the bikes and finding jobs to do during lockdown, I'd noticed that the rear spindle bolts, caliper bolts and a few other fixing's where looking a little grey and tired. So out with the zinc plating kit, the pictures don't do them justice, they where just out the passivate and where drying, once dried they have polished up like brand new and look fantastic on the bike.
Done a few more bits too, like the tin cover over the exhaust flapper valve etc.
Going to do some bit from my 916 foggy rep, they are finished with the gold/yellow passivate

Had to clean them up, depending on how bad they are, cleaning is essential part of the process. Wire brush the rust/dirt off, ultra sonic bath, de-greaser (soda crystals) ( reverse electrolysis for rust removal is superb).
I used Gateros Plating Ltd for my kit.

kuksul08 said:

I did it with a DIY process. You mix vinegar, epsom salt, some other common stuff in a bucket.

The process is simple. There are three 5-gallon buckets:
1. Acid etch bath - 2 gallons distilled water, 1 gallon muriatic acid
2. Rinse bath - 4 gallons water
3. Electrolyte bath - 4 gallons vinegar, 400grams Zinc Sulfate, 2 cups epsom salt, and a strip of zinc.

Process:
1. Clean and degrease parts
2. Media blast (if available)
3. Wire wheel to polish/smooth surfaces
4. Thorough degrease (gloves on from this point)
5. Dip in acid for 5-10 seconds, or longer if you want to strip all previous zinc plating.
6. Rinse in water.
7. Attach parts to negative lead on power supply, (and positive lead to zinc material in bath)
8. Set power supply to 2.0V constant voltage, current will vary depending on size.
9. Wait 10 minutes. Check coating, reposition if necessary.
10. Wait 10 more minutes. Check coating, reposition if necessary... There is actual science that could be applied here, but I pretty much went by 'feel' and just experimentation.
11. Once coated, rinse with water, wire wheel gently, and polish.

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You should use a clear/blue passivate immediately after the zinc plating to protect it, leave 24 hrs then polish for a longer lasting coating. I have the yellow/gold passivate to refresh some fixings on my 916 and the olive drab for the Yamaha 350.

Could You Just Apply Zinc?
In theory, yes if you wanted to you could just add a layer of Zinc onto your component. The issue is that Zinc in of itself is a very reactive metal and would be susceptible to corrosion in contact with the air and in hot and humid conditions. When Zinc reacts with oxygen it forms Zinc Oxide. When other metals such as Aluminium react with Oxygen this forms a hard and protective oxide layer which is usually desirable, but a Zinc Oxide layer is soft and porous and does nothing to protect the component from corrosion. As such White Rust would form on a component that was purely coated with Zinc.
What Is Passivation?
Passivation is a non-electrolytic process which promotes the build-up of an oxide layer. Now as above Zinc Oxide will not provide corrosion protection. As such the Passivation Process that follows Zinc Plating is a Chromate Conversion and will actually convert the metal surface into a complex mixture of Chromium compounds which will oxidise into a barrier layer. This coupled with the Zinc will provide the desirable attributes of corrosion and wear protection.

kuksul08 said:

Good tip - where do you get that? Is it just a chemical you can dip it in for some amount of time?

Having a hard time finding it online, maybe not using the right terms.

Click to expand...

Hi, yes it's just a chemical dip solution, at around 30*C temp. Dipped for approx 20 secs.
If you click the link for where I bought my kit there is some good in-depth tips and hints. Also all the individual chemicals etc to order as req.
Zinc Passivate - Clear/blue is for the shiny stuff after plating.