Zinc Plating at Home

This area is open to"How-To" section only for tutorials on fixes, etc. (no profanities/etc.). NO FOR SALE POSTINGS

Moderator: redstangbob

tbird
Posts: 2586
Joined: Sat May 10, 2008 11:07 pm
Location: Tyndall MB. Canada

Post by tbird »

Tom
I don't use brightener in my zinc and find that the gold chromate turns out more like the old gold cadmium finishes. The zinc finish is certainly bright how are you cleaning and polishing your parts.
Jim Mills
VTCI # 8071
VTCI 1964-66 Technical Editor
2002 Thunderbird
1965 Convertible
1962 Convertible (in progress)
1959 Ford Retractable HT
Many parts cars
User avatar
ABQTBird
Posts: 1183
Joined: Mon Feb 06, 2012 1:13 am
Location: Land of Enchantment
Contact:

Post by ABQTBird »

I'm cleaning with sandblast followed by a dilute hydrochloric acid pickle. The acid I have doesn't have a concentration on it, so I just make a solution of about 25% of the acid and the remainder water. It then goes straight into the plating tank.

What has me confused is what is being called gold cad. Cadmium is a dull gray metal. Everything I have looked at says it is usually chromated for additional corrosion protection. So, I am thinking that cadmium chromates differently than zinc. I did do a run with dull zinc and it came out an even brownish orange color. I'll do a run with no brightener and see how that turns out. It may be more the color your describing. What I seem to be replicating is more like everything that comes from China that has that iridescent look.
Tom in Albuquerque
61-63 Forum Moderator
1962 Corinthian White Hardtop, Medium Chestnut Metallic #89 Leather, A/C, P/W
2003 Premium Torch Red/Performance White HT, Partial Accent Interior, 1 of 47.
Past T-Bird: 1960 Convertible, 1974-1978
tbird
Posts: 2586
Joined: Sat May 10, 2008 11:07 pm
Location: Tyndall MB. Canada

Post by tbird »

Tom
Try using a wire brush to do the polishing I have recently tried the brush instead of glass bead and it seems to do a nicer job. With the chemicals from Caswell you have to be very careful of what acids you use for pickling and lots of rinsing with water.
Should have stated a power wire brush, I use the 6" bench buffer.
Jim Mills
VTCI # 8071
VTCI 1964-66 Technical Editor
2002 Thunderbird
1965 Convertible
1962 Convertible (in progress)
1959 Ford Retractable HT
Many parts cars
1943MB
Posts: 3
Joined: Wed Aug 08, 2012 10:57 am

A few questions

Post by 1943MB »

Hello ABQTbird,

Great article. I hope you don't mind these questions. Why did you switch to the Muriatic Acid as your electrolyte rather than using the original Vinegar and Epsom Salts ? I missed that in your article. My instructions say to use the Muriatic acid as a dip right after you clean the item to prevent microscopic rust from forming. Then you rinse it and place the object in an electrolyte composed of Zinc Chloride and Ammonium chloride. Which I tried and had so so results. I'm tired of all this dipping and rinsing. Based on what you did why can't you just sand blast it and go directly to the electrolyte made up of the Muriatic acid and tap water ? Did you add any brightner to the Muriatic acid as you did with the vinegar solution ? How much artificial vanilla should you use per gallon of solution ? Is the 1.5 ph level a recommended level when using the Muriatic acid ? I was using a 6volt 6 amp battery charger and I was getting huge mounds of black dusty fluffy stuff that I had to rinse off. I found out later that too much electricity was flowing through the solution causing the massive buildup. Can you slow down volt and amperage flow in the solution by varying it's ph level ? 6 volts and 6 amps seemed to be a recommended usage level. Maybe the Muriatic Acid solution would work better . You also say that your stuff was plated in just 5 or ten minutes while I read I needed to have it in there for hours. What is the criteria for knowing if you have it plated , and how much is enough ? I too use a soft wire wheel in my drill press which brings out the shine. Any help would be appreciated.

Thanks,

Lou
User avatar
ABQTBird
Posts: 1183
Joined: Mon Feb 06, 2012 1:13 am
Location: Land of Enchantment
Contact:

Post by ABQTBird »

I see you have a lot of questions. A lot has changed in my process since originally writing the article and it needs to be revised. It has turned out to be a lot of art as well as science. As you have said, one of the biggest problems is current control. You want about 140mA per square inch. So that means using a battery charger is out of the question for small parts. What I have done is gone around the house looking for old power supplies from tools, computer components, etc. I have 300mA, 1A, and 3A power supplies. So, if I am plating bolts, I use the 300mA charger, etc. based on my estimate of the surface area. The other thing I have changed is the pH. I am now keeping the pH around 4, using water and then adjusting it with the vinegar or acetic acid, which also acts as a buffer. I discovered it results in less smut on the surface of the piece. The low pH results in too much current flow which results in burning and incomplete plating. I have also changed my brightener to Karo Corn Syrup. It has to be Karo, as it is glucose. Cheaper store brands contain High Fructose Corn Syrup and not pure glucose, just check the label. I found the vanilla worked well, but I couldn't see what was going on in the bath and the garage smelled like a bakery. I have used about a half of a bottle of corn syrup per gallon.

As for the acid dip before plating, if you have just blasted your part and handled it with clean gloves (I use nitrile glove from Harbor Frieght) you can go straight into the electrolyte. You can also put the part in distilled water for temporary storage. Remember, oxygen causes flash rusting, not water.

I am still using my 300g of epsom salts (magnesium sulfate, because it is so cheap) but I am now adding 100g of zinc sulfate to provide zinc ions immediately to the solution, so I don't have to wait on the electrodes to plate out. The zinc sulfate is readily available on Ebay for $20 for two pounds.

So you have a recipe for a zinc chloride, ammonium chloride electrolyte? Then I assume you are using water then adjusting the pH? Does your recipe have a pH guideline? Where did you get your chemicals? That recipe sounds good as the zinc chloride will give you your zinc ions vs. my zinc sulfate, and it is similar to one I found in a book called Electroplating by Mohler, Chemical Press, 1969. Your bath will produce chlorine gas, but at this scale it is nothing to be concerned about. His is this:

zinc sulfate 360g/l
ammonium chloride 30g/l
sodium acetate (buffer) 15g/l
glucose 120g/l
pH 3.5-4.5

As you can see, he is using tremendous amount of zinc sulfate or in your case, zinc chloride, and quite a bit of glucose. I have found my 100g/gal is sufficient. I need to be more precise and weigh out my glucose, but of course it is a sticky mess. I have the chemicals to try this recipe, but I haven't done it yet.

So, I'm sorry this turned out to be kind of a confusing ramble. I will revise my recipe and make it clearer. You can email me directly at rt66tbird@comcast.net. This topic is so experimental that it is hard to convey in words what works and what doesn't work.
Tom
Tom in Albuquerque
61-63 Forum Moderator
1962 Corinthian White Hardtop, Medium Chestnut Metallic #89 Leather, A/C, P/W
2003 Premium Torch Red/Performance White HT, Partial Accent Interior, 1 of 47.
Past T-Bird: 1960 Convertible, 1974-1978
1943MB
Posts: 3
Joined: Wed Aug 08, 2012 10:57 am

Post by 1943MB »

Hi Tom,

Thanks for replying so quickly. The Formula I was using I found on the Internet and the chemicals I found on Ebay for a reasonable price. The ammonium chloride goes fast because of it's ratio to the Zinc chloride so next time I'll buy 2 pounds of it. The formula had no preferred PH level and when you mentioned that I became curious. I have to make up a new batch of electrolyte and was debating on trying something different. But if my problem is current flow I was thinking of getting a Dimmer control and running the power from the chargers' positive and negative side into that and then finding the right rate. I need to see how to wire that up which is probably fairly easy. I'll skip this predip rinse procedure and go from blasting to the electrolyte and see what the results are. I'll also pick up some of that Karo Corn Syrup. I was interested in your system since your concerned with cost and simplicity. Muriatic acid is cheap but boy are those fumes caustic. From what I've read that stuff can rust up everything in your garage if you keep it inside. I have a ton of those power packs laying around from portable phones that drop the voltage and could always rig those up if the dimmer doesn't work. Anyway, thanks for the information. I'll update as I learn more. And yes it does take practice to get it right. I was always looking for an easy way to do this but it looks to be a bit trickier because of so many varibles. Probably the best thing is to first get the solution you like and then fool around with the current. I've also read if you have too much current then add water since water does not conduct electricity all that well. I get my Zinc Annodes from the local Marine supply since I live on the Gulf Coast. Okay, take care. Thanks again.

Lou
User avatar
ABQTBird
Posts: 1183
Joined: Mon Feb 06, 2012 1:13 am
Location: Land of Enchantment
Contact:

Post by ABQTBird »

Get your current under control then work on your solution. Give the epsom salts electrolyte a try too. The dimmer idea sounds good. I never thought of that. I was using potentiometers from Radio Shack, but was burning them out because of the wattage was too high with a battery charger. They literally started smoking and burned out. They were rated in mW and I think I was in the Watt range. I'll look at Ohm's law and see what kind wattage I was getting and get a dimmer to see what they are rated at.

Tom
Tom in Albuquerque
61-63 Forum Moderator
1962 Corinthian White Hardtop, Medium Chestnut Metallic #89 Leather, A/C, P/W
2003 Premium Torch Red/Performance White HT, Partial Accent Interior, 1 of 47.
Past T-Bird: 1960 Convertible, 1974-1978
User avatar
ABQTBird
Posts: 1183
Joined: Mon Feb 06, 2012 1:13 am
Location: Land of Enchantment
Contact:

Post by ABQTBird »

I haven't plated in a couple of weeks, but this was the last piece I did, the throttle bracket. I used my 3A power supply and did mutliple "strikes" polishing it with 0000 steel wool in between. I had a lot of shadowing and so I had to keep reorienting the part in the bath. Since the steel wool has oil on it, I scrubbed the part with toothpaste and a brush and then rinsed it in between dips in the plating bath. It worked out well. I believe this part was cadmium plated, as I could not get the plating off with blasting. I had to etch it off in a hydrochloric acid solution. I will give it one more plate and then chromate it. You can see some of the old chromate on the before picture.
Image

Image
Tom in Albuquerque
61-63 Forum Moderator
1962 Corinthian White Hardtop, Medium Chestnut Metallic #89 Leather, A/C, P/W
2003 Premium Torch Red/Performance White HT, Partial Accent Interior, 1 of 47.
Past T-Bird: 1960 Convertible, 1974-1978
1943MB
Posts: 3
Joined: Wed Aug 08, 2012 10:57 am

Post by 1943MB »

Wow Tom ! That looks terrific ! You seem to have a really good handle on it. Did you do that using the Epsom Salts electrolyte ? How long did you have that in the tank ?

What I was going to try was to put the dimmer on the output side of the battery charger. There should only be either 12 volts or 6 volts coming out depending on my setting switch. I've got an old Schumacher type I've had for ages. Either setting has 6 amps. If Ohms law actually works then as I decrease the output of the voltage then the Amperes should decrese too. Since I'm not an expert on electricity the only thing that worries me is if I start clogging up the pipe by decreasing the output , would the backup cause the transformer to heat up ? Wonder if it would be better to put the dimmer on the input side and lower the the input voltage which would logically lower the output ? I need to research this before commiting.

Another thought was the A/C versus DC current going through an A/C dimmer. When it's coming out of the charger it's D/C. Do I need a D/C dimmer if it's on the output side ? I know I need an A/C dimmer if it's on the input side. I found a power pack with 300ma amperage but they were all 12 volts. So then my next question was whether amperage in the solution was what I'm trying to control, not voltage. Interesting how they can convert A/C into 12 volts DC with such low amperage. My 12 volt car battery has over 500 cranking amps. Saw some compact D/C dimmers on Ebay that are used on LED lighting but they all went from 12 volts to 24. Could not find one that went from zero to 12. I have a gutt feeling those would require something to store the excess voltage rather than completely shutting it off and causing a backup. This dimmer idea might end up being more costly than it's worth.

Have you seen the other method of removing rust and replacing it with new steel using the same basic method as plating. Just replace the zinc anodes with steel rods, such as rebar. Makes a nasty mess of the solution but appears to work and some people swear by it. I've heard of complete engines being derusted that way, although it can't get between cyclinders.

Another thought. If the Muriatic acid removes the zinc , why not do that first , then sand blast it ? Then maybe pickle it again in the acid or go directly to the solution. Anyway, whatever your doing is looking very excellent.

I'll be out in my garage again in a week or so and try some of my goofy ideas. We'll see how the mop flops.

Lou
User avatar
ABQTBird
Posts: 1183
Joined: Mon Feb 06, 2012 1:13 am
Location: Land of Enchantment
Contact:

Post by ABQTBird »

Yes, this was done with 300g MgSO4, 100g ZnSO4, vinegar to pH to around 4.0 and about 1/3 to 1/2 bottle of corn syrup and a 3A power supply, in about 5L of water. I used a 3A power supply and plated it maybe three times for about 10 minutes each time.

Now for the electricity. Voltage is really no concern for plating, it's the current you have to control. So I have 6V and I have 3V power supplies, but I am just concerned with their current output. Voltage is the potential energy, current or current flow is the actual movement of electrons through the branches of a circuit when voltage (the "motivational force" that causes current flow) is applied. So that what we are concerned with in the solution, how many electrons are at the cathode and how many Zn ions are flowing from the anode to the cathode.
If Ohms law actually works then as I decrease the output of the voltage then the Amperes should decrese too. Since I'm not an expert on electricity the only thing that worries me is if I start clogging up the pipe by decreasing the output , would the backup cause the transformer to heat up ?
I=V/R, so as the resistance increases, the current will decrease, and no you will not cause a backup and heat up the transformer. It is quite contrary, there is less current flowing and so the transformer works less. The backup is at the resistor, that's why they burn up if you don't have one rated at a high enough wattage.

Yes, you are correct about stripping old zinc with the hydrochloric acid. I have been stripping my parts in the acid, then depending on the condition of the part, they still get a blast to even things out, such as pitting. The blast also gives the zinc microscopic pits to grab onto. Also, if you don't like your plating results, just stick the part back into the acid and strip the zinc off and start again.

Please email me so we can take this out of the forum. It will be much easier to discuss that way. rt66tbird@comcast.net
Tom in Albuquerque
61-63 Forum Moderator
1962 Corinthian White Hardtop, Medium Chestnut Metallic #89 Leather, A/C, P/W
2003 Premium Torch Red/Performance White HT, Partial Accent Interior, 1 of 47.
Past T-Bird: 1960 Convertible, 1974-1978
blab
Posts: 158
Joined: Wed Sep 07, 2011 2:40 pm
Location: Hamburg, Germany

Re: Zinc Plating at Home

Post by blab »

First, thank you Tom for doing all the testing and writing it down. I never would have started without this.

Good results so far, the only thing that's not perfect is the "brightness". I use dark Karo syrup, maybe that's the reason. Since I bought the dark syrup I figured out that "Karo Light" is the correct syrup. This one also contains vanilla.

I did several bolts and washers so far and they came out fine. They're not as bright as industry parts but I'm OK with that. Today however I tried some tail light brackets and ran into brightness problems. I always plated two brackets at the same time. I estimated these to be about 16 sq.in. surface area which should result in 2.2A current but I usually use less (lab power supply with adjustable current, highly recommended).

First pic, 1.5 Amperes, 2nd strike, 10 minutes. Only the light areas will polish to a bright shine, other areas stay a darker silvery color:

Image

So I think I have to avoid the dark build-up which I can do with less amperes, here with 0.4 amperes, 3rd strike:

Image

Still dark build-up starting on the edges.

Finished parts, 3 strikes, you can see the border between darker and lighter:

Image

Any idea what I should change? Is it too little brightener? The wrong brightener? Tom's washer is completely light gray so it looks like I have to get rid of the dark build-up:

http://www.southsandia.com/forum/websit ... age021.jpg
Image
Since 1993.
User avatar
ABQTBird
Posts: 1183
Joined: Mon Feb 06, 2012 1:13 am
Location: Land of Enchantment
Contact:

Re: Zinc Plating at Home

Post by ABQTBird »

First, I have found that the Karo Syrup doesn't really do much, so you may consider dropping that. I have tried saccharine, but I have no idea how much saccharine is in Sweet and Low, and also artificial vanilla has been recommended. I tried the brown stuff once and they whole thing turned into a mess because I couldn't see what was going on, but it sure smelled good! Someone told me you can get the clear stuff at Wal-Mart. I admit, the process is not as bright as you will see on a commercial bolt, but I have come close using a polish such as Simichrome. It is hard to replicate what goes on with a proprietary industrial chemistry. I also am now using a 5A lab power supply. My website is out of date. Also, are you adding zinc sulfate? Also, let me report back to you on the amount of vinegar to add. My website may be indicating too much. More acid=less resistance and more conductivity in the bath.

When it comes to more complex shapes as you have there, you may try using more zinc anodes and just plate one piece at a time. You have a lot of shadowing on the parts, and maybe even some burning from over-current on the edges. I use four positioned around the tank. That will split the current among the four and hopefully reduce the shadowing. Also, pull them out occasionally and reorient them. You may even want to try reducing the total current and plate them very slowly.

I have a hood latch and a throttle bracket (same as above, but for a friend) to plate. I will try plating them this weekend and let you know how it turns out. They are both pretty complex shapes.

I hope you are not too disappointed. I have answered hundreds of inquires from all over the world. I can hardly keep up with the communication. Some report great success and some have trouble. I even had a guy make a rotating barrel plater that was really cool. He sent me a video of it. So a lot of people use this as a starting point and really have exceed what I have done.

Let me know if you want to try chromating. I do not have that on the website as I prefer to give it out personally since it involves a potentially carcinogenic chemical (sodium dichromate). It's not toxic if you just use common sense. email rt66tbird@comcast.net
Tom in Albuquerque
61-63 Forum Moderator
1962 Corinthian White Hardtop, Medium Chestnut Metallic #89 Leather, A/C, P/W
2003 Premium Torch Red/Performance White HT, Partial Accent Interior, 1 of 47.
Past T-Bird: 1960 Convertible, 1974-1978
blab
Posts: 158
Joined: Wed Sep 07, 2011 2:40 pm
Location: Hamburg, Germany

Re: Zinc Plating at Home

Post by blab »

Thank you. :smile:
ABQTBird wrote:First, I have found that the Karo Syrup doesn't really do much, so you may consider dropping that.
That's good, Karo is hard to get here (or expensive).
ABQTBird wrote:also artificial vanilla has been recommended. I tried the brown stuff once and they whole thing turned into a mess because I couldn't see what was going on, but it sure smelled good! Someone told me you can get the clear stuff at Wal-Mart.
What kind of vanilla product is this? What amounts would I need?
ABQTBird wrote:I admit, the process is not as bright as you will see on a commercial bolt
I don't mind. Less bright parts fit my old car better IMO. I just want a more consistent brightness on larger parts.
ABQTBird wrote:Also, are you adding zinc sulfate?
Yes. Here is my mixture:

2.5 liters tap water
150g epsom salt
50g zinc sulfate (hepta hydrate)
200ml Karo classic (brown)
100ml vinegar

ph measured as 4

4 Anodes, circular ones for boats. I put the parts into citric acid for a couple of days to de-rust. Then bead blast them, then de-naturated alcohol, then zinc plating.
ABQTBird wrote:Also, let me report back to you on the amount of vinegar to add. My website may be indicating too much. More acid=less resistance and more conductivity in the bath.
That would be great. If it's not the brightener, the vinegar may be responsible for the burns. The 140mA/sq.in. industry value may also be misleading as long as the conductivity of the bath and the time amount the part is exposed is unknown. I thought that maybe the bubbles are an indicator. I think less bubbles --> better plating. Lots of bubbles --> part "burning" quickly. When I tried to reach the 140mA I had so many bubbles, the whole surface of the bath was covered.
ABQTBird wrote:When it comes to more complex shapes as you have there, you may try using more zinc anodes and just plate one piece at a time. You have a lot of shadowing on the parts, and maybe even some burning from over-current on the edges.
I think it's burning. I oriented the parts to avoid shadowing. I may not understand shadowing correctly though.
ABQTBird wrote:Also, pull them out occasionally and reorient them. You may even want to try reducing the total current and plate them very slowly.
Will try both. What time amount would be "slowly"? I use 10 minutes now. If I would triple that to half an hour, the process would take too long for me (I have about 50 parts waiting, all bolts, nuts and washers).
ABQTBird wrote:I have a hood latch and a throttle bracket (same as above, but for a friend) to plate. I will try plating them this weekend and let you know how it turns out. They are both pretty complex shapes.
I'll wait for that before I continue. Did you have any problems with burns before?
ABQTBird wrote:I hope you are not too disappointed.
No, not at all. My process is not perfect yet but I just started.
ABQTBird wrote:I have answered hundreds of inquires from all over the world. I can hardly keep up with the communication. Some report great success and some have trouble. I even had a guy make a rotating barrel plater that was really cool. He sent me a video of it. So a lot of people use this as a starting point and really have exceed what I have done.
This should be collected in a forum somewhere. :smile:
Image
Since 1993.
User avatar
ABQTBird
Posts: 1183
Joined: Mon Feb 06, 2012 1:13 am
Location: Land of Enchantment
Contact:

Re: Zinc Plating at Home

Post by ABQTBird »

That was quite a response. Let me see if I can hit all the topics.

If you are measuring pH, that's great. A pH of 3 to 4 is recommended. So go by that rather than volume. I started out with litmus paper and then bought a little electronic pH meter from China for a few bucks off of Ebay.

As for saccharine or artificial vanilla (vanillin) I do not know the quantity. I got those ideas out of an old (1969) plating book I found on Amazon for $10. The author gives a recipe for the chemicals and then calls the brightener "addition agents" but doesn't say how much. The literature on this subject is nearly impossible to find, as every company must be developing there own proprietary formulas and lock it away like Colonel Sander's secret recipe. I'll go to Wal-Mart and see if I can find the clear vanillin, it is very, very cheap compared to real vanilla or Karo.

Your anode placement sounds good.

As for bubbling, if you see bubbles you probably have too much current so you will have to bring it down. As for plating time, you'll just have to try a lower current and see if you can get the results in a reasonable amount of time.

As for mass production, nuts, bolts and washers are the easy parts to plate. It sounds like maybe you have an entire car torn apart? In my case, I am usually working with small batches that I have bagged and tagged. For example, I just did a batch of bumper bolts and nuts. So I grouped them into nuts, bolts and washers. Then I put about four or five pieces in the tank at a time using 22 AWG solid core wire from Radio Shack that I have soldered directly to the copper pipe hanger, and adjust the current. I then throw them all in rinse water, and start another batch in the tank and then prep the plated ones for a second dip if necessary. Once done, they go back into clean marked bags.

You have the idea of shadowing correct. I believe what happens is if the part isn't in the direct path of the anode, the flow of ions gets disrupted and doesn't make it to the piece behind it. That can even be seen if your copper wire is too close to the work piece.

I also have a totally different chemistry called the "chloride process" that uses ammonium chloride, sodium acetate, and zinc sulfate adjusted to pH 3 to 4 with vinegar (you can use any acid actually but vinegar is so safe and easy to work with). I ran that a couple of weeks ago hoping for brilliant bolts to come out of the bath. They looked exactly the same, at a much greater effort and cost to find the chemicals. I just don't know what the secret to brightness is. I don't know if plating shops still use cyanide baths (China perhaps, as that's were all the bolts from Lowe's and such come from), but the book I have discusses mostly cyanide based plating. That may be the secret.
Tom in Albuquerque
61-63 Forum Moderator
1962 Corinthian White Hardtop, Medium Chestnut Metallic #89 Leather, A/C, P/W
2003 Premium Torch Red/Performance White HT, Partial Accent Interior, 1 of 47.
Past T-Bird: 1960 Convertible, 1974-1978
blab
Posts: 158
Joined: Wed Sep 07, 2011 2:40 pm
Location: Hamburg, Germany

Re: Zinc Plating at Home

Post by blab »

Thanks for the detailed reply. :smile:

Vanillin: this is usually a powder? And Wikipedia says it does not like do dissolve in water (about 10g per Liter @ 25 degrees Celsius).

Bubbles: my current is way too high then. Getting rid of the bubbles is what I'm going to test next. That electronic ph meter also sounds like a good idea. Lithmus paper doesn't feel that precise.

Mass production: that's only from the rear bumber area. :smile: I also plate 5 at a time (bolts etc). With 10 minutes plating time, that's about the same time I need for polishing.

Book: maybe I can find something too. The info must be out there.
Image
Since 1993.
Post Reply