Zinc Plating DIY

[Dpmulvan]

Originally Posted by tirwin

You guys are better than me. I tried my hand at zinc plating. All I accomplished was to remind myself why I hated chemistry so much in high school.

We're not better we just bought the right chemistry.
I have yet to see someone successfully make a home brew bright zinc plating solution.
All the tutorials I watched on YouTube including Eastwoods gave less than spectacular results.

[Shaun @ Tru6]

If you are doing your own plating, get some hardware from Home Depot and do some testing to see if you are getting real results.

Here's a pic I took today, 2 brake pad clips. The one on the left was plated by a shop in CT, Bass Plating. The one on the right I stripped and plated a few weeks ago. They didn't match so I wanted to replate both of them together. The pic shows what 30 seconds in an acid bath did to each of them. Hard to tell in the pic, the one on the right still has a decent amount of chromate left and all of the replated zinc. The one on the left is just smut over bare metal.

My guess is the Bass Plating clip would be rusty in a year or two with any kind of daily driving.

[Dpmulvan]

It's not as simple as Epsom salts, vinegar, water, Karol syrup, sodium carbonate et. The zinc needs to come out of the electrolyte solution bright with power applied to part at around .14 amps per sq inch. The black, green, blue, yellow chromates will not adhere properly to dull zinc or parts that have been buffed bright.
Shaun how much to tumble a 3.0 case ?

[jm993rs]

I love this threads

[Shaun @ Tru6]

I can't do engine cases unfortunately, just 901/911 and 915

[Dpmulvan]

So nice assembling clean shiny parts!

[piscator]

Originally Posted by Dpmulvan

Sodium dichromate adds corrosion protection but it won't stick to dull zinc plating. I'm not sure of the exact salt spray hours I'm sure it depends on several variables there's ton of information just google it. To answer your question
1. 10oz per gallon distilled water of sodium dichromate and 2 oz battery acid sulphuric.
2. You also make blue chromate with sodium dichromate but use nitric acid instead along with different ratios I would have to look in my notes.
This is how I do it I'm sure there's probably different ways.
3. Pull part from electrolyte bath rinse with a 5% hydrochloric acid/ distilled water solution. When a bubbles appears take out.
4. Place in sodium dichromate for 5 to seconds 10 depending on size et
5. Rinse in distilled water hang to dry.
I spent hours going through patents, reading et and wasted time and money thinking I could make a good electrolyte solution it never happened for bright zinc.
Once you look at some of the patents you'll realize it's not as easy as vinegar, salts et.
The key to zinc is the brighteners.
Caswell is the only game in town for the hobbyist, other companies will only sell with minimums that don't make sense for the home plating guy.
For $78 dollars you can buy replenishment packs and for $20 to $65 a bottle brighteners. An 8/10 plating anode off amazon and your good,

I added brightener to my latest electrolyte batch and wanted to highlight DP's excellent comments. The brightener does make the parts more shiny and enables the yellow sodium dichromate to adhere.

As always surface prep is everything. If I forget to thoroughly acid strip the old plating, small spots where old plating remains doesn't accept the new plating or the yellow dichromate very well.

The new zinc plating adheres best to the smoothest (and shiniest) areas on the part. This can be troublesome if the part is pitted. The pitted areas accept zinc but it's near impossible to polish it. The yellow dichromate dos not adhere well to these pitted areas.

Overall, I'm still very pleased with my DIY plating setup. I can plate single parts or small batches in less time than it takes to paint them. The results may not reach a professional level, but the parts are protected and I can move on with the work. For me, that's better than halting the project to drive and hour to the nearest plating company.

Thanks again to everyone who posted!

Robert

[Norm01]

I started with the DIY, don’t regre it as it got me interested and educated on the process. Results were ok, couldn’t get nice shiny parts without mechanical polishing. Ended up doing the Caswell thing. I use their zinc solution, brightener plus yellow, blue and black chromate. Results are excellent and on par with items I had professionally done. If your going to strip a car and have a tonne of parts plated, go to a plating shop. If you work on your car piecemeal at a time, buy a kit it will save you a fortune. The problem with the platers for small batches is they have a minimum load fee.

[piscator]

Norm, could you tell me if there were any differences between using the different colors (yellow, blue, black) chromates? Did one do better on less than perfectly shiny parts or were the results similar? Thanks!

Robert

[Norm01]

Originally Posted by piscator

Norm, could you tell me if there were any differences between using the different colors (yellow, blue, black) chromates? Did one do better on less than perfectly shiny parts or were the results similar? Thanks!

Robert

The most impressive is the blue which is really clear. Parts are extremely shiny. Black covered extremely well and yellow you know. I did like you and bought the brightener to add to my DIY. It didn’t do anything however when I bought the Caswell kit I had instant results with shiny zinc plated parts. You have all the basics so just go with their zinc plating refill.

[Norm01]

Pics of my setup and results.

[piscator]

Thanks Norm! You got great results with that nice setup of yours! I ordered the Caswell zinc resupply and the black chromate this morning. I appreciate your advice.

Robert

[piscator]

What I love about this DIY process is that it fits into the work flow so nicely. If you’re doing a major refresh and set the plating up nearby, it’s easy to dunk a couple of parts while doing something else. Twenty minutes later, after a quick polish on a wire wheel, the project continues with just that short interruption.

Being able to plate these brake parts, yesterday, enabled me to complete one project and move on. This is an internal brake part and doesn’t need a fine professional finish. And there’s no way to paint it effectively. Electroplating insures the entire part is protected from corrosion.

I found the following in a document that ClickclickBoom suggested, ‘…will make your eyes bleed.’ He’s right, but there’s fascinating stuff in this PDF! Thanks Click!

https://www.faa.gov/documentLibrary/media/Advisory_Circular/AC_43.13-1B_w-chg1.pdf”

6-194. c. “c. Zinc coatings offer protection in an
identical manner to cadmium, and the correc
tive treatment for failure is generally the same
as for cadmium-plated parts. However, the
amount of zinc on aircraft structures is very
limited and usually does not present a mainte
nance problem.”

[Dpmulvan]

If your having issues with yellow chromate adhering add an ounce or two of sulfuric acid per 2 gallons of solution.
Blue chromate is just sodium dichromate with nitric acid instead of sulfuric.
When you pull part from electrolyte you need to rinse in a mild 5% hydrochloric solution before dipping in yellow chromate and after you pull it out of yellow chromate you need to dip rinse in just distilled water then hang to dry. If you don't rinse after yellow chromate it will come out dark and uneven with runs.

[tperazzo]

Great advice here! Thanks for sharing!

[piscator]

DP, you really know your stuff! Thank-you!

I may have a container of sulphuric acid that I got from a plumbing supply house. The stuff I bought is kinda brownish and is used to un-clog drains. I'll see if I can find it.

Hydrochloric acid is, I think, muriatic acid, and that I do have. I have not been rinsing my part in anything but tap water before dunking it in the yellow chromate. And after the yellow chromate, I haven't been rinsing, at all.

My result, is as you describe -- "If you don't rinse after yellow chromate it will come out dark and uneven with runs.'

So I now know how to do it the wrong way! There's certainly room for improvement!

DP, if you have a moment, are there any special instructions on using black chromate? I ordered some with my zinc replacement chemistry and look forward to trying it.

Robert

[Norm01]

Originally Posted by Dpmulvan

If your having issues with yellow chromate adhering add an ounce or two of sulfuric acid per 2 gallons of solution.
Blue chromate is just sodium dichromate with nitric acid instead of sulfuric.
When you pull part from electrolyte you need to rinse in a mild 5% hydrochloric solution before dipping in yellow chromate and after you pull it out of yellow chromate you need to dip rinse in just distilled water then hang to dry. If you don't rinse after yellow chromate it will come out dark and uneven with runs.

Dp, please hang around. Your type of knowledge is what we need.

[bsherrard]

enjoying this thread and getting ready to take the plunge with DIY plating myself.
Norm - how did you prep all those small carb parts?

Brook

[1QuickS]

I use Caswell for most of my chemicals and I do recommend a mild acidic dip before chromating, I use a sulphuric dip where others have mentioned Muriatic.

My plating work area includes a roll-out dip tank for cleaning, a roll-out tray for my various chemical dips, an ultrasonic tank and my plating tank. The plating tank has anodes setup for plating while suspending parts from wires which is good for larger bits but I found that wire hanging will place too much zinc onto threaded features. I developed the rotating basket and since then I can plate an entire set of hardware for a Weber project in one process.

First picture shows components in the work area and second shows rotating basket, anode & cathode hooked up to positive & negative studs on the top of the bench. The rotator is a BBQ rotator.

It took awhile to come up with all of this but the result is I can keep all the little carburetor bits in-house. A big positive!

[piscator]

Paul, that is impressive! I mixed my Caswell zinc chemistry today and plan to try it out tomorrow. Thanks for posting those great photos!