Zinc Plating DIY

[Dpmulvan]

Originally Posted by 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!

Nice barrel set up did you make that yourself???

[piscator]

DP, I know you've read a great deal on the subject and set up a beautiful facility. I have appreciated and followed your advice in my experiments. Fundamentally I agree with you -- especially regarding bright zinc and chromate finishes.

Where my experience differs from yours is with the home-brew solution. I did "spend the $70" on the Caswell kit. Actually I bought two, so that's $140. When I got interested in this subject I wanted to do some side by side testing.

I've mixed up several batches of the Caswell chemistry and it works GREAT! I've also mixed up several batches of the formula presented in the home-brew link -- and it works GREAT! I'm not advocating for one over the other. I'm just reporting on my experience.

Both recipes have worked well for me, and will, I think, do a 'bang-up' job for DIY zinc plating of single or small batches of parts. Large batches, large parts, and/or exquisite shiny surfaces are probably best left to the professionals, who, as you said, likely guard their formulas.

BTW: I also bought the Caswell brightener that you recommended. I've used that brightener in both the Caswell solution and the home-brew. It's made a noticeable difference in both cases. Thanks much for that tip!

As reported, I''ve not been successful with the Caswell yellow and black chromates -- probably for the reasons you've stated and/or I'm doing something wrong. No problem. I'm happy with what I have. My 'one-bucket' kit is ideal for the sundry, one-off, plating requirements of my home shop.

[bsherrard]

Piscator
What is that part? I found one of those under my car and can’t identify what it is.
Brook

[bsherrard]

Thought I would add my recent experience with DIY plating. Shout out to Norm for his post on his process and setup...I used this as the basis for my plating setup. I have gotten very good results with the zinc plate and the yellow chromate - this weekend was my first attempt. I was not able to get the black chromate to work well so still trying to figure that out.
Here are some pictures of my setup, a stud with zinc and parts drying.










I really see the benefit of being able to plate parts on an individual basis as you need them.

Brook

[Norm01]

Originally Posted by piscator

Norm, thanks, I really appreciate your input! You may very well be right about 'staying wet' and not touching the part. I wear gloves, so I'm not transferring oil from my fingers, but the wire wheel I use between strikes may be transferring crud to the part. After polishing on the wire wheel, I do rinse or wipe the part down with denatured alcohol, but maybe that's not sufficient.

Let me ask, in 'staying wet' are you transferring the part from the electrolyte bath, to the distilled water rinse, and then to the chromate without polishing the silver zinc buildup that's deposited by the electrolyte?

Doing it this way, I would think that the chromate would come off when you eventually polish the part. But I'll try it.

By the way, I did try sulfuric acid for my initial acid bath, but I didn't get any better result than I did with the hydrochloric. This is something that Eric at PMB also suggested.

Here's some photos of the E-brake tubes I plated yesterday. As you can see, the silver zinc came out quite well. The chromate photo, I'm embarassed to even post. When these parts came out of the chromate bath they had a consistent, albeit weak, overall yellow cast. In the process of drying, without my ever touching the part, it turned into a splotchy mess.

Before chromate:



After chromate dunk and dry:

Robert, something is definitely wrong. I go from zinc, to distilled dip, I then lift from distilled dip and spray with fresh distilled water over the distilled bucket then straight into Chromate, 30 seconds or so. Another important thing I found is do not touch the parts after the Chromate dip, it is very fragile in the first 24hrs. Use the same wire and hang it in front of a fan to dry. A shinny Chromate requires shinny zinc, I first bought the Caswell brightener and tried it in my homebrew and found it didn’t make a difference. I had tried polishing the zinc like you did but couldn’t get a good Chromate. My break through was with the Caswell zinc + brightener, no polishing and great results. I have larger parts plated and no one can tell the difference between my parts and the pros.

[Norm01]

Oops forgot to mention, there is a distilled water rinse after Chromate, I just gently dip in water, no bottle spray then hang parts.

[Norm01]

https://youtu.be/hTupOgImpWo

Probably the best home plating video I’ve seen.

[Dpmulvan]

For those having issues with chromates here's a few tips.
Caswell's Chromates are not the best and sort of pricey.
Go on eBay and buy some sodium dichromate 10oz weight to a gallon distilled water. This next step is very important!! Add 2oz of battery acid to the dichromate
The battery acid helps the chromate bite into the part. Sodium dichromate will last forever when it gets weak simply add 2oz of battery acid. You can also make blue chromate but use nitric acid instead of sulphuric .

[Dpmulvan]

Originally Posted by Norm01

Robert, something is definitely wrong. I go from zinc, to distilled dip, I then lift from distilled dip and spray with fresh distilled water over the distilled bucket then straight into Chromate, 30 seconds or so. Another important thing I found is do not touch the parts after the Chromate dip, it is very fragile in the first 24hrs. Use the same wire and hang it in front of a fan to dry. A shinny Chromate requires shinny zinc, I first bought the Caswell brightener and tried it in my homebrew and found it didn’t make a difference. I had tried polishing the zinc like you did but couldn’t get a good Chromate. My break through was with the Caswell zinc + brightener, no polishing and great results. I have larger parts plated and no one can tell the difference between my parts and the pros.

Before you solve chromate issues you need to solve zinc plating issues.
The photo looks like the parts have been burned from using too much amperage for those two parts alone amperage should be no more than 1 amp or so.
Are you using degreaser before zinc?? What kind of zinc are you using? What power supply??? How much brightener?

[piscator]

Originally Posted by bsherrard

Piscator
What is that part? I found one of those under my car and can’t identify what it is.
Brook

Brook, NICE JOB! I love your setup, Especially your Porsche parts Xmas tree in front of the fan!

The tube I posted is part of the emergency brake. It inserts into the notch on the back-side of the rear trailing arm/hub assembly. The emergency brake cable runs through the tube feeding it into the hub where it passes through the 'flippy floppy things" (German technical term) that actuate the brake and is secured by the castle nut and cotter pin. Two tubes, one for each side.

[piscator]

DP and Norm,

Credit and thanks to you gentlemen for the progress I made yesterday. And, I’m afraid, shame and disgrace on myself. Norm your comment that something was clearly wrong – and DP, your observation that my parts looked burned lead me to investigate my power supply.

Yes, there was a problem. I found that current was fluctuating from 0 to 3.6 amps. Obviously the cause of recent poor results. Last week, I had it ‘dialed in’ at .9 amps and since my bolts and batches have been roughly the same size, it seemed to be working fine. I left the settings alone and only turned on the power switch. Something went awry. I’m embarrassed!

I got this ‘Dr Meter’ power supply through Amazon before I started plating. Dialing up current or voltage has always been a bit finicky. Turn a knob just slightly and it hunts up and down the scale before settling. If you have a suggestion for something better, I’d probably replace it.

NOW THE GOOD NEWS!!

Once I identified the power problem, I had some success with the black chromate. It’s not great, but we’re moving in the right direction.

Suphuric Acid!

DP, I started experimenting with sulphuric acid for the initial bath; based on your advice. Yesterday I tried your method of giving the part an acid dip between zinc ‘stikes’ and before chromating. I think this made a big difference. Thanks!

Norm, All my chemistry is from Caswell, including two batches of zinc solution. I’ve gotten great results with it. I’ve also gotten equal results with the homebrew. Going forward I’ll probably standardize on all Caswell, just to be consistent. Thanks for all your help!

[Norm01]

Well, I’m going to contradict DP who’s been a great help on this thread. There may be nothing wrong with your power supply, if it’s jumping it may be your current is limiting. I set my current to maximum and set voltage to zero, I then turn the voltage up until parts just start to bubble and back off a bit, I think I’m always below 1 volt. I’ll need to take better notes next time. I’m not controlling current, I’m controlling voltage.

[Dpmulvan]

It's the amperage that matters, I set voltage at 6 and leave it there.
I've had issues with cheap Chinese power supplies in the past make sure you turn them on before hooking up leads to cathode and anode or you can burn them
most plating done in a 2 or 3 gallon bucket will be between 1 and 3 or 4 amps.

[piscator]

Norm, It's sounds like you've used a similar power supply. I'm going to try your method, today, just to see what happens.

My power supply is very finicky. Turn the current of voltage knob, just slightly and the meters fluctuate all over the place and then settle. Then you have to guess how far to move the knob to make an adjustment and then wait for the meters to settle again. There seems to be no consistent correlation between the knobs and the meters.

DP, Thanks for the info! 1 to 4 amps is what I've used in most of the plating I've done. I roughly estimated the square area to be plated and used the calculator at Caswell to set the current. Came out to .9 amps for smaller parts and 3.6 when I did my brake calibers.

With my crazy power supply, when I move the 'current' knob, the voltage also changes. Based on Norm's experience, I'm going to try setting one control at maximum or minimum and only adjust using the other knob. If that doesn't work, I may just chuck it.

[Dpmulvan]

Originally Posted by piscator

DP and Norm,

Credit and thanks to you gentlemen for the progress I made yesterday. And, I’m afraid, shame and disgrace on myself. Norm your comment that something was clearly wrong – and DP, your observation that my parts looked burned lead me to investigate my power supply.

Yes, there was a problem. I found that current was fluctuating from 0 to 3.6 amps. Obviously the cause of recent poor results. Last week, I had it ‘dialed in’ at .9 amps and since my bolts and batches have been roughly the same size, it seemed to be working fine. I left the settings alone and only turned on the power switch. Something went awry. I’m embarrassed!

I got this ‘Dr Meter’ power supply through Amazon before I started plating. Dialing up current or voltage has always been a bit finicky. Turn a knob just slightly and it hunts up and down the scale before settling. If you have a suggestion for something better, I’d probably replace it.

NOW THE GOOD NEWS!!

Once I identified the power problem, I had some success with the black chromate. It’s not great, but we’re moving in the right direction.

Suphuric Acid!

DP, I started experimenting with sulphuric acid for the initial bath; based on your advice. Yesterday I tried your method of giving the part an acid dip between zinc ‘stikes’ and before chromating. I think this made a big difference. Thanks!

Norm, All my chemistry is from Caswell, including two batches of zinc solution. I’ve gotten great results with it. I’ve also gotten equal results with the homebrew. Going forward I’ll probably standardize on all Caswell, just to be consistent. Thanks for all your help!

You want to use hydrochloric acid aka muriatic acid in the pre chromate wash, use sulphuric ( battery acid) at 1 or 2 oz per gallon in your chromates when they lose power.. It's the amperage that's important not voltage, set it to 6 volts and forget it. Parts will plate better if you use caswell or some other degreaser heated to 190f for a 10 to 15 soak. Also a circulation pump in electrolyte helps a lot.

[Norm01]

I think I sort of misled you with my post, yes it is current that counts but I achieve it with the voltage. Try this, figure out what your rough estimate of amps needs to be. Set voltage to zero and current to max, raise the voltage until the desired current is reached on the amp meter. After a few batches I stopped calculating amperage, I just raise voltage until parts slightly bubble and back off a bit, my current draw always seems about right for the size of part.

[piscator]

Norm, you were not misleading. I understood what you meant and tried your method this morning. I set the current on max, raised the voltage to bubbling and then backed off a bit. It worked perfectly! I plated a large bolt using .9 amps which brought the voltage up to 7.4

That was a great tip! Thanks!

[Norm01]

https://www.finishing.com/336/41.shtml

Good read

[tperazzo]

Originally Posted by Dpmulvan

For those having issues with chromates here's a few tips.
Caswell's Chromates are not the best and sort of pricey.
Go on eBay and buy some sodium dichromate 10oz weight to a gallon distilled water. This next step is very important!! Add 2oz of battery acid to the dichromate
The battery acid helps the chromate bite into the part. Sodium dichromate will last forever when it gets weak simply add 2oz of battery acid. You can also make blue chromate but use nitric acid instead of sulphuric .

Are you referring to 10oz of sodium dichromate in powder form?

[Dpmulvan]

Yes 10oz powder by weight.