Plating

First try at plating today. Pleased with the results. Not cheaper to do this yourself on a big pile of small parts, but I wanted to do it and show the kids. $555 bucks in stuff here. $255 in kit from Caswell, roughly $200 for cheap power supply, and $100 bucks in pots, thermometers, alligator clips and the like.

Basically it goes like this, sand or bead blast your parts so they are spotless. Degrease them in a darn near boiling degreaser powder/water mix (from Caswell), Mix up a solution that if I had to guess is mostly vinegar and salt (from Caswell) in distilled or RO water. Circulate the solution with an aquarium pump and heat the solution to 110 degrees F. Hang two zinc plates in it, (also from Caswell), and hook the positive lead of a constant current DC power supply to the zinc. Hang your steel parts that you are plating from copper wire from a copper tube and hook the negative lead from the power supply to that. You run .14 amp/square inch through the parts for 20 minutes. You are basically putting the positively charged zinc in solution and depositing it on your negatively charged steel. The pulley cages took 1 amp total, and the flap hinges took 6 amp total. I had the voltage set at a max of 12V, but in reality, it doesn't take near that much. The amps are what drive and regulate the process, so a power supply with constant current is what you want. Most of the switching power supplies have both CV and CC. I would not recommend the one I have pictured here. It is of poor quality. I have used it twice and had to fix it both times before using it. It did not come from Caswell.

After parts are plated with zinc, rinse them with distilled water, and dip them in the yellow chromate/distilled water solution at 80 degrees for 30 seconds to give them the cadmium color. Rinse again and let dry.

You rinse the parts back to the buckets you did the last process from to keep from contaminating your baths and wasting materials. You cover the buckets with gasketed lids until next time.

The stainless pots have water in them to heat the solution in the plastic buckets. Tank heaters that won't contaminate the process are expensive. This old range from my wife's parents was free 23 years ago and I use it for heating 7018 rod, making jerky, and now plating. It will also bake cookies and cook pizza!


You can homebrew the elixirs and buy the zinc from somewhere other than Caswell. If you did this I'm sure you could do this lots cheaper than what I have done, but I didn't want to do that on these parts and I figured I didn't need to complicate things on my first try.

The only semi-nasty stuff is the chromate or color. It is an etching acid. Keep it off your soft and tender parts. I'd compare it to battery acid. Have a fan going, don't be stupid with it.

You can make these parts shiny with a brightener in the plating bath, but I opted to leave them dull like what I think of with true cad. From what I read the zinc does the lion's share of the protecting. The chromate does some too but is more a matter of preference.

Again, not an expert, not a professional plater. Just trying and learning new stuff by slowly building an airplane in my shop with my kids.

Lots of fun.


Thanks,

Jim​

All the small parts for the wing are plated. I am down to the longer stuff that won't fit in my plating tank (bucket). I have a plan for this stuff, flap/aileron hangers and the like. Going to give it a shot before I take any pictures of that.

In doing small batches like I am, it is hard to keep the final color consistent. You can see there is some variation throughout the parts. I've learned that it pays to take the zinc anode out between every batch and clean it. It gets like a wet soot on it during the plating process. The soot washes right off with a spray bottle of distilled water. The anode also keeps breaking down into the brine solution even when there isn't current flowing through it. If you pull it out between batches it will last longer and keep the solution cleaner. I filtered the plating solution once through coffee filters, I'll likely do it again before the bigger parts. You also have to monitor the color that comes out on every batch and add a small amount of brightener solution periodically. You can do some nice looking stuff with a setup like this, and if you can keep it to one batch, which isn't much, your colors will be consistent.

Uniform color wasn't the most important thing to me with this. Most of this stuff is buried in the wing. What isn't will get some paint shot over it anyway. I'm confident all of this stuff has a good coating of zinc that won't blister or flake off. For good measure, I have rattle canned a thin layer of clear over top of all the small parts(no pictures of that yet). It takes some of the vibrant color away from the shiniest of parts, but it improves the luster on the dullest and helps improve the color variations.


Sharing some pictures of my "cheap" little blast cabinet setup. I bought it to clean up cylinders with walnut shells on the engine project/projects. I have since switched over and tried glass beads and finally aluminum oxide for the current project.

All I had for a compressor at the time was a 22 gal portable. I knew it wasn't near enough, but it was what I had and it worked well enough to start with. Surprisingly, I didn't lock it up. Finally saved enough for what I wanted and got it playing this weekend. 60gal two stage, regulated down to 120psi, teed in with old compressor and about a 10 gallon portable tank. This is nice. Big compressor actually shuts off while blasting, and with nearly 100 gallons of storage, gives it enough off time. C-Aire is the make, they are the same company that made my little compressor, hopefully this one is just as tough. Both were at least assembled in the U.S. Best of both worlds, smaller compressor for small jobs and everyday stuff, big compressor when needed.

Some other blast cabinet improvements were the hillbilly dust collector and two $5 dollar magnetic/Velcro LED lights for in the cabinet. Both the dust collector and the lights work surprisingly well. Just need to pulse down the baghouse between batches to keep the Shop Vac filter from blinding(shake).

More pictures soon.

Thanks,

Jim​

Finished with plating the larger parts today. All that really needed to happen to accomplish this was a different shaped plating tank. Hung the parts in diagonally with the zinc along the sides. Worked well.

Had some rework to do on some of the smaller parts. The colors varied slightly but more importantly the difference in shininess bothered me. I sprayed clear over top of about 12 parts to remedy this. DON'T DO THIS. When the clear was still wet, I was happy. When it dried, I was not.

The problem is Caswell recommends no brightener for a Cad look. This is fine for the first few batches, but slowly your parts start looking like bronze baby shoes with no oil slick colors in them. The solution is to add this brightener in the plating solution to liven things back up. When you do this, the finish is too shiny and starts to dull to acceptable then too dull, repeat. This is tough to control and hard to get repeatable results.

I did some reading and tried three different quick acid dips after zinc plating and right before the chromic acid(color) dip to bring the zinc to a bright sheen. Sulfuric acid was a fail. Muriatic acid was a fail. Nitric acid at a 1% solution was a huge success! The picture of the spar attachment bracket halfway dipped is the difference. I quit using the brightener and used this method on the small parts I had to redo and all of the large parts. Very uniform, very easy to repeat, nice coloring.

Things I learned:

If you blast your parts down to bare metal, plate and chromate them, and are unhappy, 30% more or less Muriatic acid(hydrochloric with impurities), will strip all of the plating back off in about 30 seconds. Do this outside with a broom handle length stick and a wire. When you take the lid off of the bucket and the acid contacts moisture, it smokes. Be upwind. Don't get the acid on anything you like meaning your body, your eyes, or your lungs. When you dip the part and the fizzing stops, you are done. Immediately rinse the steel parts with water then distilled water and immediately re-plate. You won't get the zinc plating back off easily by blasting even with aluminum oxide.

If you chromate your zinc plated parts and are unhappy with the color, 5% more or less Muriatic acid for about 10 seconds will strip the chromate back off and leave the zinc. Rinse the parts with distilled water quickly after doing so to stop the acid and immediately chromate(color) again. This removal must be done when the chromate is still soft. If you let it harden overnight, you are back to the nasty 30% Muriatic bare metal strip down.

A 1% Nitric acid quick dip for 3 seconds after zinc plating and before chromating will make the zinc a nice dull silver color. This is what you want for repeatable results. If you don't have that, strip it all off and zinc plate again. Nitric acid can be bought at a 4% solution and shipped to you non Hazmat. At higher concentrations, that is not the case. It is wicked stuff...

Make sure all of the blasting media is off of your parts before plating. Do this by rinsing with water, then distilled water, then immediately plating. It doesn't take much to wreck the plating, it will stick to the parts like weld splatter and spread across the part like a black horrific cancer. Again, the cure is the nasty 30% muriatic acid stripping.

A little zinc will go a long way. I was worried about not having enough. The pieces I started with were .040 thick, and 4"X8". I was able to plate all of the steel parts pictured here and you can see what was left. It is now about the thickness of a razor blade, but it was enough.

Bath temperature does not seem as important as what Caswell recommended. They recommend 110 degrees for the zinc plating bath, and 80 degrees for the chromating bath. With my larger parts, I had temps down to 70 degrees for both with the same results.

I would skip the zinc brightener solution. Too hard to replicate results between batches.

I whipped up a home brew plating solution after I was done to see if I could get the same results. White vinegar, Epsom salt, sugar. It plated, but it was slow.... I believe if you wanted a good thickness of zinc, it would likely take up to 12 hours at the same .14amps per square inch. Still very thin plating after 2 hours. This elixir was not worth the effort.

In a nutshell if you want to try this, buy the plating solution and the chromate from Caswell. It is worth the money. The zinc likely is too, but I'm going to try a product called Moss Boss which is a roofing product available at Menard's, Home Depot and the like to see what it acts like with the Caswell plating solution. It worked with the homebrew.

Anyway, here are the completed pictures. I'm happy with it. Also included the Hillbilly Dust Collector. For some reason it didn't make it through on my last post.

NOT A CHEMIST, OR AN EXPERT. PLAY WITH STUFF LIKE THIS AT YOUR OWN RISK!

Thanks,

Jim​

Originally Posted by Jim A.
Finished with plating the larger parts today. All that really needed to happen to accomplish this was a different shaped plating tank. Hung the parts in diagonally with the zinc along the sides. Worked well.

Had some rework to do on some of the smaller parts. The colors varied slightly but more importantly the difference in shininess bothered me. I sprayed clear over top of about 12 parts to remedy this. DON'T DO THIS. When the clear was still wet, I was happy. When it dried, I was not.

The problem is Caswell recommends no brightener for a Cad look. This is fine for the first few batches, but slowly your parts start looking like bronze baby shoes with no oil slick colors in them. The solution is to add this brightener in the plating solution to liven things back up. When you do this, the finish is too shiny and starts to dull to acceptable then too dull, repeat. This is tough to control and hard to get repeatable results.

I did some reading and tried three different quick acid dips after zinc plating and right before the chromic acid(color) dip to bring the zinc to a bright sheen. Sulfuric acid was a fail. Muriatic acid was a fail. Nitric acid at a 1% solution was a huge success! The picture of the spar attachment bracket halfway dipped is the difference. I quit using the brightener and used this method on the small parts I had to redo and all of the large parts. Very uniform, very easy to repeat, nice coloring.

Things I learned:

If you blast your parts down to bare metal, plate and chromate them, and are unhappy, 30% more or less Muriatic acid(hydrochloric with impurities), will strip all of the plating back off in about 30 seconds. Do this outside with a broom handle length stick and a wire. When you take the lid off of the bucket and the acid contacts moisture, it smokes. Be upwind. Don't get the acid on anything you like meaning your body, your eyes, or your lungs. When you dip the part and the fizzing stops, you are done. Immediately rinse the steel parts with water then distilled water and immediately re-plate. You won't get the zinc plating back off easily by blasting even with aluminum oxide.

If you chromate your zinc plated parts and are unhappy with the color, 5% more or less Muriatic acid for about 10 seconds will strip the chromate back off and leave the zinc. Rinse the parts with distilled water quickly after doing so to stop the acid and immediately chromate(color) again. This removal must be done when the chromate is still soft. If you let it harden overnight, you are back to the nasty 30% Muriatic bare metal strip down.

A 1% Nitric acid quick dip for 3 seconds after zinc plating and before chromating will make the zinc a nice dull silver color. This is what you want for repeatable results. If you don't have that, strip it all off and zinc plate again. Nitric acid can be bought at a 4% solution and shipped to you non Hazmat. At higher concentrations, that is not the case. It is wicked stuff...

Make sure all of the blasting media is off of your parts before plating. Do this by rinsing with water, then distilled water, then immediately plating. It doesn't take much to wreck the plating, it will stick to the parts like weld splatter and spread across the part like a black horrific cancer. Again, the cure is the nasty 30% muriatic acid stripping.

A little zinc will go a long way. I was worried about not having enough. The pieces I started with were .040 thick, and 4"X8". I was able to plate all of the steel parts pictured here and you can see what was left. It is now about the thickness of a razor blade, but it was enough.

Bath temperature does not seem as important as what Caswell recommended. They recommend 110 degrees for the zinc plating bath, and 80 degrees for the chromating bath. With my larger parts, I had temps down to 70 degrees for both with the same results.

I would skip the zinc brightener solution. Too hard to replicate results between batches.

I whipped up a home brew plating solution after I was done to see if I could get the same results. White vinegar, Epsom salt, sugar. It plated, but it was slow.... I believe if you wanted a good thickness of zinc, it would likely take up to 12 hours at the same .14amps per square inch. Still very thin plating after 2 hours. This elixir was not worth the effort.

In a nutshell if you want to try this, buy the plating solution and the chromate from Caswell. It is worth the money. The zinc likely is too, but I'm going to try a product called Moss Boss which is a roofing product available at Menard's, Home Depot and the like to see what it acts like with the Caswell plating solution. It worked with the homebrew.

Anyway, here are the completed pictures. I'm happy with it. Also included the Hillbilly Dust Collector. For some reason it didn't make it through on my last post.

NOT A CHEMIST, OR AN EXPERT. PLAY WITH STUFF LIKE THIS AT YOUR OWN RISK!

Thanks,

Jim



thanks, I bookmarked this...

please consider starting a separate thread about plating and put this in, or if there is all ready a thread on it, adding it to it.... to make search easier for us​

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Originally Posted by Jim A.
White vinegar, Epsom salt, sugar. It plated, but it was slow.... I believe if you wanted a good thickness of zinc, it would likely take up to 12 hours at the same .14amps per square inch. Still very thin plating after 2 hours. This elixir was not worth the effort.
Thanks,

Jim



thats all I've tried, and also was not impressed.... got the job done but dull & ugly.. thanks for the comparison

let me know if any other home-brew formulas work... caswell will not ship up to me in alaska....​

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Mike,

One I ran across was on thisoldtractor.com/zinc Gregory Bender. His parts look like they might brighten with the nitric acid dip. Might catch fire too, I don't know. Before my teeth get wiggly, I'm gonna quit experimenting with plating solutions. I'm not qualified to even guess. The one homebrew I tried sounded pretty harmless. His concoction looks to involve distilled water, zinc oxide powder, sodium hydroxide(lye, caustic soda?). There were also some other homebrews mentioned there. I've never tried Lutefisk because of the lye thing... Used lye on the farm to remove well, most anything stinky, dead, and gross. Bones and all.

I'll try to figure out how to move these last two posts.

Wish I could be more help to you.

Thanks,

Jim​

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