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Zinc Plating at Home

118K views 34 replies 12 participants last post by  Snakeoil 
#1 · (Edited)
Over the weekend I tried a zinc plating process for small parts at home that was entirely a do-it-yourself exercise. By that I mean that I did not buy any plating kit or anything elaborate for the process. I read about the process on the Honda 305 forum and based on photos publised by the author and having a bunch of crummy looking parts on my Scrambler, I thought I'd give it a try.

I'm sharing this here because I think everyone on this forum who is interested in sprucing up their old bike should know how to do this. This topic may have been covered on this forum before so I don't want to rehash old news. I'll just give you a quick rundown of what is needed and provide a picture of parts I plated over the weekend. I will be using the process when I get into the resto of my '66 Bonnie.

Materials
Zinc - I used pure zinc roof strips sold to prevent fungus on roofing
Vinegar
Epsom Salts - 100gm/liter
Sugar - 120 gm/liter
Small 12vdc power supply (3 volts minimum)
plastic pail
digitial multimeter or DMM (for measuring milliamps)
small variable resistor (potentiometer or pot) - 500 ohms Radio Shack
Brass wire brush
Digital timer - not absolutely required, but makes things easier.

Building the System
You make cathodes from the zinc plate and line the walls of the pail with them. Connect them all together using copper wire and the end of that wire becomes the positive terminal for the set up.

String another copper wire across the top of the pail that is electrically isolated from the cathodes. That wire is the negative terminal and the wire from which you will hand the parts to be plated. We'll call this the top wire.

Mix vinegar, Epsom salts and sugar until all is dissolved and fill the pail with the solution. Hang the parts to be plated from the Top wire with either copper or stainless steel wire so the part is fully submerged in the plating bath. DO NOT LET THE PARTS OR THE HANGER WIRE COME IN CONTACT WITH THE CATHODE!! THIS WILL SHORT OUT YOUR CHARGER. The current flows thru the bath, which is an electrolyte and conducts current via the Epsom Salts you added.

Connect the negative lead of the charger to the negative terminal of the set up (Top wire) . Connect the positive lead of the charger to one terminal of the potentiometer. Connect the positive lead of the DMM to the other terminal on the pot. Connect the negative lead of the DMM to the positive terminal of the set up (cathode wire). Set the DMM to milliamps or amps as your meter requires.

Look at the rating on your charger. It should give the output voltage and the output current. It may give the voltage and watts instead. If it gives watts, just divide the watts by the output voltage to get the output current in milliamps. That output current is your max current. If you exceed that, you will damage your charger.

Part Prep
You need to remove all the old plating and any rust prior to plating. You can bead blast, acid clean, wire brush, sand, whatever you prefer. Remember that the plated finish is only as good as the finish on the base metal being plated. I use Phosphoric Acid to remove any old Cad plating and any rust. Stubborn rust like deep pits gets bead blasted. Then with rubber gloves on to prevent greasy finger prints, degrease the part thoroughly in something like acetone, dry it and then suspend it in the bath.

Plating
With everything connected and the part in the bath plug in your charger. Adjust the pot so that the current in ma is at or below the max output current for your charger.

Leave the part in the bath for 10 to 30 minutes. Unplug the charger and remove the part. The part should be plated with a dull light gray coating. Brush the plated surface (this is called carding) with the brass brush until the bright zinc plating appears. You can put the part back in the bath for a second coat, which I normally do.

Keep in mind that the plating will add anywhere from 0.0005 to 0.003 inch of plating, depending on how long you plate it. So fitted parts may need to be masked with paint or tape or sanded down when finished. The axel in the attached photo would not fit thru the wheel bearing when it was done so I polished the plating from the shaft section. The OEM plating was only on the ends of the axel as well.

Attached is a photo of some 305 Scrambler parts I plated over the weekend. This was the first time I've ever done this, having read about the process on the 305 forum on Friday. Here's a link to that thread so you can read the other details I observed as I did this. http://www.honda305.com/forums/viewtopic.php?t=6584

I've also attached a photo of my set up. My pail is a 1/2 gallon pail that had hot tube chemicals in it before. Try your local diner for similar plastic containers. They get tons of them and normally toss them out. Don't use a huge 5 gal pail because proximity of the part to the cathodes determines the time required to get a good plated surface. Also note that the plating is line of sight. By that I mean the zinc ions travel from the cathode to the anode (part) in a straight line. So if you have only one cathode, the surface facing it will plate better than the surface not facing it. This is why I say to surround the outer wall of your pail with zinc cathodes all hooked in series. This also means that for parts like the axel spacers and that big axel nut in the photo, I had to make a small cathode to fit inside the ID of those parts and not touch. I made a smaller set up with a small plastic butter tub to plate the ID on those parts first, and then did the outer surfaces in the set up shown in the photo here.

You won't be disappointed with the results. Happy Plating!

regards,
Rob
 

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#3 ·
Those roofing strip are best found at roofing supply houses. Zinc is zinc so you could use any source, including a scrap yard. Zincs for boat use can be used and you could slice them up if you had no other source.

You can order the zinc roof strips on-line. The brand I used is called Shingle Shield. A box is about $50 and holds 16 3x36 inch strips. I made my set-up from one strip which with tax comes to just under $4.00/strip. I thought about selling individual strips at my cost plus postage to offset the initial cost but I'm hanging on to them for now. Might use what is left on my roof when I reshingle it as I have a roof fungus problem.

I would suggest you talk to some local roofers. They may have leftover strips they would sell or perhaps even give to you.

Another source of zinc is old drycell batteries. Not alkaline or rechargeable batteries. Just the standard good old drycells. The outer casing of those batteries is pure zinc. You can slit it and peel it off the gooey tar insides and use that. Think of all the batteries we have thrown out over the years. We could be plating forever with all that zinc.

regards,
Rob
 
#5 ·
I have to make a correction to the instructions in this post, but the actual post is locked and won't let me edit it again. Not having any experience with plating, I have the terms cathode and anode backwards in my instructions. The positive and negative terminals are correct as the current flows from positive to negative. But in an electrolytic solution, the cathode is the negative terminal. So the workpiece is the cathode and not the zinc and vice versa for the zinc.

I was using battery terminology, which is reversed. My mistake. Ignorance abounds when you've never done stuff like this before.

If you copy and paste the instructions to a Word document, just do an Edit, Find and replace all the Anodes with a work like RALPH. Then do Edit, Find and replace all the Cathodes with Anode. Then go back and do Edit, Find and replace all the RALPHs with Cathode.

Sorry for the mistake.

regards,
Rob
 
#8 ·
Ohio,

Well, you made me actually measure what kind of resistance I'm adding to the circuit in order to control the current. My pot did not cost me anything because anytime I throw something out that has good parts in it, I strip it first. I think the pots I have came from an old metal detector I pulled out of somebody's trash last year. I have a 1K ohm pot on one set up and a 2K pot on the other, only because that's what I had in the basement. The range of adjustment is nil as I can barely feel the pot move for major swings in current.

So, I measured the 1K pot to see where it was set from the last parts I plated yesterday. It is set at 5 ohms. This would explain the lack of fine adjustability with my 1K pot.

Radio shack has a 25 ohm rheostat for $3.99 on their website. I would think that would do it for you.

So although the 500 ohm pot will work, I think a pot in the range of 25 to 100 ohms would be more appropriate. Another correction to the original write-up.

regards,
Rob
 
#9 ·
Great info Rob. I had a 305 scrambler too, in 1966. Seen a couple around for sale, but not that many. Put a lot of miles on it, then bought my first Triumph, a 1967 Bonnie.

Eastwood Company offers a zinc plating kit. They also sell the zinc bars. There were also some instructions on the site that I linked to below, to possibly help answer some of the questions.

Hope it helps,
Ron

http://www.eastwood.com/images/pdf/10049Q.pdf
 
#13 ·
That really does stir memories Rob. Mine did have painted fenders. I don't remember if it came with a muffler like yours, but I do remember removing the muffler and putting in a disk type of apparatus that you could twist where the pipes were either straight through or quiet.16 yrs old. Absolutely beautiful bike. How's it run?
 
#18 ·
Thanks Tiger. Runs good. Smokes a tad, but with 14K on it, I am not surprised. You had the same exhaust (at least from the factory) on you bike only difference was your muffler was not welded to the top pipe. Original 250 versions came with straight pipes from the factory. Gonna run it as it this coming summer and may tear into it next winter. We'll see, I have a '66 Bonnie waiting for the resto work and a '47 knuck waiting to go back together. I'm finding that I'm enjoying the small bikes as much if not more than the big bikes lately. I have an S90 that is an absolute hoot to ride. And when I pull into a parking lot or better yet a Harley dealer, everyone wants to talk to me about the bike. It's like I was riding a Vincent.

Went to look at a '57 HD 165 today. It's the big brother to the Hummer. Too much money for the condition of the bike. But it gave me an idea. I might just buy an old Hummer frame and put something like an old Honda 250 Elsinore engine in it and make a hybrid classic. CR250 in a Hummer frame. If I add some Yamaha parts I could call it a Crummy 250. Would be a cheap bike to build and be like nothing else out there.

I really need to retire soon. I need more free time.

regards,
Rob
Again apologizing for non-Triumph content. I hereby promise to stop, right now.
 
#15 · (Edited)
Snakeoil,

This is great information and will certainly save a lot compared to buying a kit but anyone who is thinking about doing this please remember that cadmium dust is toxic. Media blasting, sanding, polishing and grinding cad plated parts is dangerous to your health. Fumes from welding alloys containing cadmium is especially dangerous and can cause fairly sudden death. You can google "cadmium dust" if you don't believe me. If not for this hazard and for issues with disposal of chemicals resulting from stripping cad plating chemically, I would be jumping into the zinc plating process with both feet.

Now, zinc plating bare steel is pretty much hazard free. It's stripping the cadmium that is dangerous. I've gotten more cautious with age and will probably leave replating to those who can better deal with the hazards.

Be safe guys,

Henry
 
#16 ·
Snuff-or-not's
That's what they were. How'd you remember that? I haven't seen them since the 60's. I always ran with mine open.
 
#19 ·
I remember the 250 Elsinore dirt bike engines being really strong in the early 70's. I had a Husky 400 CR that was hard to beat (always had to ride 15/20% above my capabilities to stay ahead), but the Elsinore my friend had was a hoot to ride. It came on like a shot of everclear.

Again apologizing for non-Triumph content. I hereby promise to stop, right now.
We're all gear heads here, everything's good. I'm getting old enough where I think the Honda Dream 305's are looking really good. Jimmy Bush's first bike.

Ron
 
#20 ·
I bought it with just a few miles on it and had a ball wearing it out. 56,000 mi in a year and a half but I never thought it was good looking. Sold it and bought a used Super Hawk. I always lusted for a Scrambler so when the Hawk got tired I bought one of them. My brother wrecked it when I was in the service. Didn't get my first Triumph til after I got out of the service.
 
#21 ·
Zinc Plating bath recipe

Others have asked this question before and although it's buried in this or one of the referenced threads on the topic, I thought I'd simply post the recipe I use for the electrolyte.

Dissolve 1/4 lb of Epsom salts and 1/4 lb of white sugar into a quart of white vinegar.

regards,
Rob
 
#22 ·
Others have asked this question before and although it's buried in this or one of the referenced threads on the topic, I thought I'd simply post the recipe I use for the electrolyte.

Dissolve 1/4 lb of Epsom salts and 1/4 lb of white sugar into a quart of white vinegar.

regards,
Rob
Nice... and, simple enough for me.
Thanks.
-- alonzo
 
#24 ·
I did some searching on the web and found other DIY home plating process for doing zinc. They involve pickling the parts in strong acids, rinsing in distilled water, etc. I'm sure they do a better job and the end product is more durable. But when you considering the precautions you have to take with some of those chemicals and with the process I've been using you can do it in your basement with zero protective gear or risk, I can live with the reduced durability.

regards,
Rob
 
#25 ·
Rob --
I've just started plating a few parts using your info and I must say that I'm impressed! Brought some crappy nuts and bolts back from the dead (appearance.)
Thanks for your contribution on this.

-- alonzo
 
#26 ·
Glad you like how the process works. I have to admit, I'm a skeptic for anything that seems too good, too cheap or too easy to be true. But this zinc plating process is way easy and the results are excellent. I've even had situations where I had a wrench slip or Phillips screwdriver do its thing and rather than kicking the anvil, I simply cleaned up the buggered fastener and replated it.

This means that all the old fasteners on our bikes can all be made to look almost like new. Big savings. Plus, it is also great for special items you make and want to protect from the elements.

regards,
Rob
 
#27 ·
A great thread. It should be made a sticky on the Tech Tips side.

I did loads of fastenings on my last bike and have just got the kit out again.

I am sure this point has been made before, but If you drain off the elecrolyte it seems to keep well in the bottle, left in the bath ,with the zincs, I have found it goes off. My last lot has remained usable for over a year.
 
#28 ·
You are right, Doug. First left in the bucket it will continue to eat away your zinc. It also will fill with what appears to be some form of smut, probably a type of zinc corrosion product. Or it could be the impurities in the zinc with is no 100% pure.

I made a funnel out of a soda bottle that fits snugly into the gallon vinegar jug. When I'm done plating, I simple pour the bath back into the jug and pop the cap back on.

What you will find is with time the bath starts to get dark. That's a sign it's time to make a new bath.

Save all the remnants of your intial zinc plates. My first set of plates looked like lace curtains after doing my 305 hardware. Cut those bits up and drop them into your new bath while it is still in the jug and let it sit overnight. They will be gone in the morning and your bath will be nicely charged with zinc ions. This will slow down the destruction of your actual zinc electrodes. I learned this the hard way. First bath was made and put into the bucket with the new zinc electrodes. Within a short period of time, they were the above described lace curtains and the thickness of tissue paper. I made new electrodes and they lasted well over a year. The point is to pre-charge your new bath with zinc before you start plating. Overnight is usually enough time. If all you have is one big chunk of zinc, then just leave the bath overnight in the bucket for the same result.

regards,
Rob
 
#29 ·
#30 ·
Informative thread.

I use a different bath formula, but I did some experiments to try to get at film thickness. By weighing a piece of known area before and after plating, I calculated thickness by using the density of zinc.

I was able to repeatably get 1 mil (0.001") thicknesses. This is considered a fairly heavy plating layer for zinc. If I tried to go too much beyond this, the finish got rough.

Theoretically, for a fully charged bath, zinc should plate at the rate of 1.22 grams per amp-hour. This is equivalent to 1 mil over a square foot for every 14.3 amp-hours.

Also, I use gelatin as a an additive. It doesn't brighten much, but is supposed to give a finer "grain".
 
#31 ·
I believe when they use the term "brightener" it means the same as providing a finer grain to the zinc plate.

Yes, Alonzo, I've measured the thickness. I've measured the diameter of shafts before and after. I've been able to put quite a bit of zinc on a shaft. On axels, I've had to put the axel in my lathe and polish down the plate for the axel to slide into the wheel bearing.

I also built up a zamak casting on an ignition switch so that the worn threads worked again. That took lots of trips thru the bath. But it worked.

Never used molasses. To me, sugar is sugar.

regards,
Rob
 
#32 · (Edited)
Rob--

I think commercial platers get shiny plates right out of the tank, and I assume this is due to their proprietary brighteners. It's not hard to find the chemical names for some of these, but finding a source and actually buying them as a home plater is a different story.

My bath produces, as I think you said yours does, a matte grey finish that is easily brought to a very nice shine with little effort, so the drawback isn't a big one for small operations like ours.

I once had a plater slip me a little bottle of a proprietary copper plating additive called "Copper Brite". I don't know what is in it, but including just a tiny amount of it to a copper bath produced amazing results.

Ed
 
#34 ·
Thank you

Thank you, thank you, thank you!!!

Rob, and all that have contributed to this thread, thanks very much for this info on zinc plating. I'm finding it to work very well and have rescued several parts that would have cost me $$'s to replace (e.g., Chain adjusters at ~$25+ each.) Even a 5/16" x 2" bolt costs a couple of bucks anymore. I just wish that the Phillips heads on the case screws weren't so buggered or I'd be plating them too. I saw a post here somewhere that was saying that beginning (or after) 1968 Triumph hardware was zinc plated and not cadmium. Maybe that's why some of the less rusted (but still grungy) stuff zinc plates out so nice..

Anyway, I'm having fun with this (my shop is starting to look like Dr. Frankenstein's laboratory.) And, I love the fact that great results can be had with ordinary household chemicals rather than fancy proprietary stuff.

-- alonzo

BTW: I'm starting to experiment with "rust removal" with electrolysis. http://myweb.tiscali.co.uk/andyspatch/rust.htm
 
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