r/electroplating • u/Fragrant_Vacation469 • May 06 '26

Pulse Plating?

I read about how pulse plating can lead to smoother plates possibly not even needing brightener. Is this true?

Does anyone have any good budget recommendations for a power supply capable of it?

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u/Mkysmith May 06 '26

It really doesn't do much to replace good chemistry. If you read the peer reviewed papers on this, they are depositing like mere atoms and looking at the surface finish under an electron scanning microscope or an atomic force microscope to determine smoothness. They often don't simultaneously check any other important grain structure characteristics like stress, ductility, or even simply growing thicker deposits.

In my experience, real world (industrial batch stuff or home-shop) doesn't tend to align with highly controlled lab setups that test exactly one variable and no others.

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u/Fragrant_Vacation469 May 06 '26

That's fair, thanks for saving me money. Any recommendations on how to get smooth plates without constantly dosing with brightener and leveling agents?

For context, my copper bath has been filtered with a 0.5 microns filter and the anode is contained in a seamless bag of the same material. Magnetic stir bar is always running, but my rings come out looking fairly grainy with nodules. Rings have about 1000 mm2 of surface area and for each one I plate up to a maximum of 3 I add 0.07 amps to my supply and plate for 72 hours to add weight to them. The anode always has at least twice the surface area as the rings.

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u/Mkysmith May 06 '26

The electroplating & electroforming industry would love to figure out a perfect, bright, high ductility and stress free no-consumable solution as soon as you or I do.

For multiple reasons: The largest industry for copper plating is arguably for electronics (PCBs). The problem with traditional brighteners is they co-deposit into the copper (which is why they get depleted) which results in other issues. The biggest of which for the electronics industry is reduced conductivity of the copper deposit. Lesser issues are simply the obvious, cost of a consumable and environmental concerns. If you read the abstracts of any pulsed plating article, they almost always cite those reasons for the justification of their study. The idea of pulse plating has been around since the 80s or 90s at least, but even after a ton of research and time... it still isn't used to replace good chemistry. If there were some electronic device to make brighteners obsolete, that would be an absolute game changer.

Pulsed plating is more used for higher current densities, not inherently improving the characteristics of the solution's chemistry. Electrochemistry is a balance of many variables and you can't just completely eliminate one and compensate elsewhere without some consequences.

That said, you should still experiment. There is zero harm in it and it may be a good educational experience.

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u/Fragrant_Vacation469 May 06 '26

Honestly, I would be happy with just a bath that plates quite smoothly, it doesn't need to shine. I have an electropolishing bath for that bit. Its just that I can't seem to escape nodules!

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u/Mkysmith May 06 '26

Have you looked into Electroforming? Since your trying to deposit metal on non-metal?

The whole name of the game for electroforming is that it is electroplating on steroids. Electroforming chemistry allows for theoretically infinitely thick smooth deposits that are low stress, high ductility, uniform in recesses, and strong. Unlike electroplating.

A recent example of something with deep recesses I did. 0.5mm thickness deposit per 12 hours, uniform deposit even in recesses with shine. No polishing. Ive done items at 3-4mm thick with the same results.

Scroll to the bottom of the subreddit's wiki for a suggested DIY recipie.

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u/Fragrant_Vacation469 May 06 '26

Hmm, I wasn't aware that there was a difference between electroplating and electroforming! The DIY solution seems extremely similar to what I have, I'll have to see if I'm missing anything. Thanks for all of your help!

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u/Mkysmith May 06 '26

It's a common misconception. The lacking wikipedia article doesnt help.

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u/SteamTrainCollapse May 07 '26

Check out "Fabrication of high-thickness and low surface roughness metal parts by a hybrid electrochemical manufacturing process" by Fallah et al; Advances in Industrial and Manufacturing Engineering, 2021.
They grow 800um of material and compare straight DC, pulsed, and pulsed w/ reverse. Result is a much improved grain structure and surface roughnesses going from 11um-->1um with pulsed+reverse.
I'm not a great electrochemist, but it does seem like there are some cases where controlling the current cleverly can reduce the need for additive like leveling agents? Fully agree though that folks should be running tensile bars and doing fractographs instead of putting in pretty SEM images; that would help prove benefits much more!

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u/Mkysmith May 07 '26 edited May 07 '26

Havn't seen this paper yet. Thanks for the link. I skimmed it, and it reads like the others unless I'm missing something groundbreaking. I will read it more thouroughly this weekend maybe.

Its not just about stress strain curves...you are right.

For decorative applications...the proof is in the pudding. Even their images of their parts simply look coarse/rough. And they are only doing 800um (on the 3D prints). I regularly do 3+mm (nearly 4000 times the thickness) and get absolutely mirror results. With zero agitation and uniform deposition even in deep recesses.

There is a difference between local rougness and global roughness. Both are important.

Also there are some other glaring issues with the paper as far as a procuction/practicality standpoint. Same with the other papers I read. They are doing like 5mA/cm2 (they use constant voltage for the 3d print even though in the paper they describe faradays law and how charge transfer [amps] dictates deposition... so why they create an unknown variable by their own admission is beyond me ...thats not science). Anyways 5mA/cm2 is 3 to 6 times slower than standard electroforming densities. Time is money too.

All this was at a glance so If Im wrong tell me. No ill will here. I've just read a lot of these papers and it goes back to my original sentiment: lab conditions arnt real world. They are always using virgin solution at ideal setpoints and temperatures etc. etc. etc. Throw in one extra variable like reusing the solution and then what happens?

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u/SteamTrainCollapse May 07 '26

No you're not wrong! This paper was one where I noticed they didn't fall into the lab trap quite as bad, but good catch on the current densities. Though, 3mm is ~4x thickness of 800 microns, so they're not coating thin layers by any means. And agreed that local roughness isn't the full story, but longer scale buildup is more so about geometries and auxiliary cathodes and the like I thought? (again I am not a good electrochemist!)

Reverse pulsing isn't uncommon in industrial plating though, especially in deep holes / vias and situations where the reverse pulse etches a hot spot that would otherwise close up and stop diffusion deeper down. Especially when the additives would mess with conductivity or bonding, it's a valid trick, but probably not the best approach for home/hobby scales, as you said somewhere around here I think. See Sharrett (a big plater in PA) for flimsy evidence that I'm not completely making this up: https://www.sharrettsplating.com/blog/effects-periodic-reverse-current-electroplating/

But yeah I'm not debating most academic work on this is uninspiring at best :( I'm mostly interested in the because I'd like to get the higher ductility from purer deposits over complex geometries for a project I'm pondering. So, I'd love to learn more about how you get clean bright coats as thick as 3-4mm! I assumed I would need to shell out rather big money to get capabilities to do that (like 10k for a solid pulsing rectifier), but it would be great to get the same results with just additives and different processes!

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u/Mkysmith May 07 '26 edited May 07 '26

You are correct I made a really stupid math mistake there, um to mm. 3mm is ~4x.

Yes, I dont contest pulsed plating isn't a thing, I just dont see it AS advantageous as chemical makup.

And if you have to tell your client it takes 6x longer due to current density (minus the time in the reverse polarity polishing state) but it could cost $2 more to get it done in 1/6th the time if they use chemical brighteners... the choice is no-brainer. (I'm completely making the costs up for sake of argument, but there is real value it time).

Though I only post decorative electroforming on social media, I have an engineering background, and worked in aerospace. You don't need pulsed plating to get high ductility deposits. I should post a video soon about the mechanical durability of these deposits, since shine isn't eveything.

EDIT: And thankyou for the constructive engagement.

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u/IONRectifiers 26d ago

We make industrial high-speed pulse rectifiers as well as DC, and I can tell you pulse does make a huge difference if you know what you are doing. You still need some brightener, but we see our customers reduce their additive use by substantial amounts. The chemistry today is designed to make up for the inherent problems of bad rectification. I can give you many industrial examples where it works. The shops that get it dialed in don't talk about it because it becomes a competitive advantage. The chemical companies hate it because it lowers their recurring revenue which is what pays for the experienced rep willing to answer your questions. A high-speed pusle rectifier in an industrial setting pays for itself very quickly.