After looking for a local shop to put a yellow zinc finish on some parts I have, and coming up empty, I did some research and found out that many people do it themselves. That got me reading about it and ultimately I decided to try it for myself.

The problem is the plating process is not working for me like it should. For an electrolyte solution, I'm just using tap water, white distilled vinegar, and some cleaning soda. From everything I've read and watched online, there seem to be lots of variations on this and they all work pretty well. I hooked up a D battery between my part and my zinc anode, and while I got a little bubbling, nothing happened. Then I thought maybe I didn't have enough current, so I rigged up two D batteries in sequence, but the result didn't change.

Admittedly, this isn't something I know a lot about and figured I could save some $ and learn something in the process. Can anyone out there who has a better understanding of the process give me advice on what I'm doing wrong?

http://www.caswellplating.com
http://www.caswellplating.com/yellow-chromate.html

Check this site for a cheap kit and they have yellow chromate also.

Actually, I bought my chromates from the site you mentioned. However, I was trying to avoid buying their electroplating kit which costs roughly $200. There doesn't seem to be anything special about it making the DIY route seem very feasible. If all else fails, I will end up going that route, but for now, I'd like to try to troubleshoot what I'm working with right now.

tap water probably has contaminates in it, have you tried distilled instead?

Seems like a big hassle to me! I just take my parts to the local plating house and ask for zinc yellow. They price it by the square inch of material covered.

No, I haven't tried distilled water yet, but its probably worth a shot.

Andy, I had originally planned on taking my stuff to a local plating house, but discovered there are no plating houses in the area.

We are talking St Louis area? Not to be critical, but I find that almost impossible to believe. Are you sure you are asking the right questions locally? For Instance, "yellow cad" is a red flag nowadays, "yellow zinc", is not.

jcc, I even asked here on moparts.

https://board.moparts.org/ubbthreads/ubbt...tml#Post1875759

Came up empty. I had thought about shipping stuff off originally, but now think it would be better to stay local or do it myself in case I need additional parts plated.

A few suggestions, from what I have seen at my platers shop to be shipped out, anybody who does any HP auto chassis bracketry, etc, likely yellow zincs something, anybody who rebuilds in mass automotive accessories, like starters, alternators, etc yellow zincs, anybody who builds/manufactures electrical cabinetry, fixtures, racks, likely plates something, any of the above should be able to share who they use, or have used in the past. Lot of aircraft stuff also gets plated, new and rebuilt, but requires a higher end plater I believe, and that's is still a big industry in St Louis, correct?

Member Eric manual can do anything you want.


https://board.moparts.org/ubbthreads/ubbthreads.php/users/216/3404.html

I typed "zinc plating st Louis mo" into google and came up with 33 hits.

How does Caswell recommend disposing of the spent chemicals these days?

Try using a battery charger. It works for me. See:

http://a12mopar.com/yabb/YaBB.pl?num=1366043257

A battery charger is going to have more amps than D cells, so that may be your problem. Even a battery charger is capable of plating only a relatively small area. I use 4 zinc electrodes around my bucket since plating only happens on the side of the part facing the electrode. That's why zinc plated tubing is not plated on the inside.

I think the sugar mentioned in this link should actually be Karo syrup. You can try either and none and see what happens.

The health risks with hexavalent chromium in the Caswell sodium dichromate are extremely high. Follow all safety precautions such as rubber gloves and face shield/mask, don't breathe any fumes, don't get any on your skin, and do proper disposal.

You can get more yellow and rainbow effect cheaper than the Caswell by buying 1 lb of sodium dichromate powder on ebay for under $17 shipped. Mix 372 grams of powder with 1 gallon of distilled water and add 34 ml of 35% sulfuric acid. You can get battery acid (should be 35% sulfuric acid) from most car parts stores for $10 or less. This is called a Cronak solution (Google it). Dip your zinc plated part in the Cronak for 15 seconds, immediately rinse in a bucket of clean water, and dry with a heat gun. In case of Caswell, dip for about 2 minutes. Dip your part on the end of some wire, of course.

Excellent info kentj340. I'll be messing this this again today, so I'll probably try your suggestions.

Think Erin Brockovich

https://en.wikipedia.org/wiki/Hinkley_groundwater_contamination

kentj340, I tried your method today with the electrolyte solution you recommended and also the battery charger and had much better results. I think I still need to tweak my method slightly, but its definitely getting the job done now. Gonna have to pick up an aquarium bubbler which I think will help, but at least I'm getting a layer of plating now.

Thank you for the excellent feedback!

Pictures?!?

While plating your parts, you can also plate a piece of copper wire from house wiring at the same time. Using a micrometer on the unplated part of the wire vs the plated part, you can see how much zinc you've deposited. Divide by 2 since you are measuring 2 sides. Commercial plating thickness is in the range of 0.0002 inch on one side. So when you get about twice that thickness you know you've done about all you can do.

The Cronak dip is a slow drying gel. That's the reason for the heat gun. After drying with the heat gun, hang the part up for a while or a few days to prevent damage to the coating.

I bought an aquarium bubbler too, but I doubt it helps any.

I checked and found out the Karo brand corn syrup is correct, rather than sugar. The purpose is to keep the zinc deposits finer grained which should help brightness. There is an ingredient in the Karo that helps this, but it's not the sugar.

Here is a better recipe for electrolyte than the link above.

Mix together 300 grams of Epsom salts, 100 grams of zinc sulfate, 200ml of white vinegar and about 1/3 bottle of Karo into 4.5 liters of tap water and stir.

You can buy 2 lbs of zinc sulfate for $9 with free shipping on ebay. An electrolyte will not plate zinc until it contains enough zinc ions. You will eventually put zinc ions into the electrolyte if you keep on plating long enough without the zinc sulfate, but having it speeds up the process. Tap water is fine for this as minor impurities don't matter.

140mA per sq. in. is the optimum current for zinc plating. A battery charger has relatively high enough amperage (maybe 2 to 10 amps?) that you need to be plating quite a few parts at once to get the optimum current per sq. in. of surface area.

To find the area of your parts, you can make some short cut area calculations for shapes like bolts, nuts, washers, etc. in a spread sheet and input their dimensions. After you have done a few area calculations a pattern will emerge with average, big, and small bolts, nuts, screws, and washers.

To find out the amperage of a battery charger requires some care. Most multi meters are capable of measuring only a very small amperage. Too much current and the meter will fry. AMHIK. A safe way is to measure the voltage and ohms of resistance and derive current by the formula I=E/R or amps=volts/ohms. The amperage of my battery charger varies with load, so the real output in a plating setup has to be determined. To calculate the amps output of a 12v battery charger, you will need to find out the actual voltage which is probably going to be something like 13.5v.

You can also use other smaller power supplies. The voltage does not matter at all for plating, only the amps. An example is a transformer from an old modem or router with input 110v AC and output 6v DC/750 mA. This unit should do for plating about 5.3 sq. in. of parts, which should be a lot fewer parts than with a battery charger at 2+ amps.

You can definitely plate one small part with a 2+ amp battery charger, but getting closer to 140mA per sq. in. will improve results.

Using correct amperage, it will take maybe 10 total minutes of plating time for most parts. Two or three sessions of plating work the best. At third time intervals or when the part looks blue-gray, wear rubber or vinyl gloves, remove, rinse, scrub with a brass wire brush and toothpaste, rinse in alcohol, and resume plating. Position the part differently relative to the zinc anodes each time to prevent "shadows" or unplated areas. When finished, clean the part with a brass wire brush and toothpaste again. You can polish with fine steel wool and toothpaste if desired. Rinse in alcohol.

It's best to have a good supply of cleaned up parts on hand before you start plating. I like to clean the parts with vinegar, but you can media blast also. After degreasing with dish soap, hot water, and a tooth brush, I soak in vinegar for quarter or half day increments until the fastener is bright and clean. Then I hand steel wire brush each fastener all over for a minute or two on a wooden board wearing a leather glove. You can store the parts in denatured alcohol to prevent flash rusting until you have a big enough batch to start a plating session. In case of flash rusting, dip briefly in muriatic (hydrochloric) acid, rinse, and plate.

DIY plating is not speedy, but it can save money, and you will have control. Local commercial platers want a minimum batch fee of $70. But what if you find some more parts that need plating after the first batch is done? With a home setup it's easy to plate one more part. And you can plate in multiple small batches as your restoration progresses.

After plating, you can dip the part in chromates of yellow-rainbow, black, green, blue, and olive drab to match the color of the original part. These are available from Caswell or you can make your own yellow-rainbow Cronak as mentioned above. Note that "clear" or silver colored zinc parts are dipped in the blue chromate. The blue is so subtle that most people don't see any blue. Next time you are in a hardware store, look for the bluish tint on clear zinc plated fasteners. The purpose of chromating is to temporarily prevent white rusting of the zinc plating. In other words, chromates may stop corrosion for only a few years or less, so it's a good idea to wax your newly plated and chromated parts for more protection.