Chapter 21. Tests.
Galvanization.
28.03.2026
*In this post, I'll also share my tests with Blackening Copper after Electroforming. This post will likely be expanded with new tests (I plan to test copper varnish). Everything related to 3D printing and 3D modeling will be described in the next post. All plastic parts used in the experiments are parts from Victory's previous project.
**All experiments are visualizations of various (both routine and extreme) conditions for creating a copper layer on plastic. Through trial and error, I wanted to show everyone what would happen in a given situation... and ultimately, I chose the appropriate parameters and conditions that achieved the desired result. I will show the version I chose as the working one in future posts when I actually make the parts for the model.
So, what is Galvanization or electroplating? If you think it's complicated and not for you, after reading this post, you'll realize it's much simpler than you thought.
Laziness is the engine of progress. I've always looked for a way to do things faster and with less effort. So, I searched for a way to produce identical parts in large quantities. And the only way is 3D printing.
But many might argue that this isn't as authentic, that painted plastic will never look like blackened metal... and I completely agree!
But what if you coat the plastic with metal?! And then blacken it... and voila – electroplating is your thing!
So, what is electroplating? It's a method of coating one metal with another, in very simple terms. This can be used for gold plating, silver plating, zinc plating, and many other things, but we're interested in copper plating.
But! I just said it's coating another metal with metal, but what does plastic have to do with it? So, for copper plating to work, our plastic part needs to be electrically conductive. But how can we do that? One option is graphite! Regular graphite, the kind you find in pencils. But applying this powder is problematic, so there are ready-made sprays that can be used to apply a layer of graphite like a coat of spray paint.
And now our part is ready for copper plating. And if anyone thinks this is just for show and that such a part won't be able to withstand the load, it all depends on the time it takes to copper plating. The longer the process, the thicker the copper layer, and such a part can even be sanded. Next, I'll show you my experiments with loads on such parts (rims and hinges), and you'll see... no, you'll even be surprised at how durable they are!
So what have we come up with? If a part looks like metal (which it essentially is), if it bends, polishes, and blackens like metal, then what difference does it make what's inside? Many people copper-plated tin (chemically or galvanically), which is a brittle and very flexible metal. How is it any better than plastic, which is much stronger (for its intended purpose). By the way, weight (for those who prefer metal) can sometimes play a cruel joke, when a heavy cannon is torn from its carriage on a finished model during transportation due to shaking...
So, if you've read this far, I suggest you take a look at my experiments in electroforming. I'll try to explain everything in detail so that even a child can follow it. Let's go!
But first, here are some recommendations for mandatory implementation.
Protective equipment: mask, gloves, glasses.
1. Details. I glued the details made of SLA photopolymer plastic (which I printed on a 3D printer) to the CA. They need to be positioned so they don't block access to each other's side walls or touch each other. This will prevent the graphite coating from being applied properly. It's important to understand that the fasteners should be located where the part won't be visible. Large parts are best fastened at several points, preferably hidden from view and on protruding areas. I'll talk more about fasteners later. Also, closed parts (bells, buckets) need to be fastened sideways to prevent air bubbles from forming inside. This is important!
2. Graphite. Applying graphite varnish to the parts and to the adjacent wire is essential. The aerosol spray is applied like paint and is odorless, but its downside is that it's not cheap. Apply it carefully to avoid any gaps or drips. It's best to apply it once, then check everything and repeat. The layer is very thin, so it's best to apply a little more to avoid creating gaps later, but don't go overboard (again, it's not cheap, costing 17-20 euros).
Very important! You must wait until the surface is completely dry. Although graphite appears to dry within a few minutes, this is deceptive. Complete drying takes 2-4 hours! If this is ignored, the layer will be loose and fragile, the process will be slow, and a "sugar" will form on the surface.
Caution! Graphite is very finely dispersed and must be sprayed in an isolated area. If you get it on the floor, the dust will spread everywhere and be difficult to clean. You have been warned!
4. Electrical equipment. We need a DC power source. Any spare charger will do. I used a 5-volt, 1.2-amp one. This is more than enough for our purposes. We connect the positive and negative terminals of this charger to the XY-SK35H step-down converter (easy to buy on AliExpress for 10-15 euros). We'll set the desired current and volts on it (more on this device later). From this step-down converter, we need to connect two positive terminals and one negative terminal (or two negative terminals, too).
5. Anode (+). Two copper plates (pre-polished to remove oxide film with steel wool or sandpaper, important!). It's advisable to make covers out of non-woven material, like a coffee filter. This is necessary to prevent copper debris from getting into the solution (see below for the importance of this). The plates should be above the solution level, and the contacts with the wire should be on the surface.
Again, the sedimentation rate will slow if the solution isn't stirred. The copper will settle to the bottom, and the process will take a long time. To ensure the copper is distributed evenly throughout the solution, the solution must be constantly moving. Either stir it regularly or install an automatic system to stir it for you.
8. Cathode (-). The negative terminal must be connected to the wire with our components. The distance from the copper plates must be the same for all components. The components should never touch the copper plates. (You can make two negative terminals, and run another one to the other side; that's what I did.)
9. Solution. I bought a ready-made one, which I recommend. It's an acidic solution for bright copper plating. You can try making it yourself, but you'll need pure copper sulfate (not agricultural grade), sulfuric acid (battery grade), alcohol, salt, and thiocarbamide. But if you buy everything, the cost will be more than a liter of the ready-made solution. Yes, you'll end up with five times more raw materials, but why bother? This solution has no expiration date, and with filtering, one liter is enough for many models. Look for it in specialized stores where jewelers shop; it costs 5 euros.
10. Converter settings. This type of equipment is quite expensive
if it is professional. I bought this device for 12 euros. Look for the
XY-SK35H on AliExpress. How to set it up: 1) connect to the network (+-
wires from the power supply), 2) turn on the Power button (ON), 3) then
press SW and make sure that "IN" is NOT there, that is, so that we see
the outgoing settings and not the incoming ones, 4) press V / A and in
the set cv (00.00) setting, set 02.00 Volts (this parameter is not
mandatory, it will automatically change as needed depending on the
Ampere, but the upper limit can be set to 1-2 V), 5) press V / A again
and in the set cc (0.000) setting, set 0.080 Amperes! This is important,
not 0.8 but 0.08!! This parameter is the most important. 6) after
inactivity, the settings will be saved. Done.
These parameters aren't universal, but rather an example with this number of parts!
You need to calculate according to the following principle:
- Start and until complete copper plating - 0.01-(0.02) Amps per square centimeter.
- After the entire surface is coated - 0.02-(0.03) Amps per cm². (But you don't have to change this if you're not in a hurry).
How to calculate the area of the detals: Take the part and draw
the outlines of all the surfaces that will be copper-plated around it on
a piece of paper. If the part is a cylinder, mentally unfold it into a
single plane. Add up the area in square centimeters. For me, it was
approximately 2 x 4 = 8 cm, 8 x 0.01 = 0.08 Amps. This step is very
important for selecting the current.
11. After an hour, you can slightly increase the current (amperes. Volts
are set automatically; if there are more parts, you can set the maximum
to 2 volts). This isn't necessary if you're not in a hurry, but since I
added a coin and a pendant to the copper plating, I increased it to 0.1
amps. After the entire surface of the parts is copper-plated, you can
increase the current to 0.02-(0,03) amps per cm², but this isn't
necessary.
It's important to understand that: 1) if the current (amperes) is low,
the process may proceed very slowly or even stop. 2) if the current is
high, the copper plating rate will be higher, but there's a risk of
localized thickening and pimples. The current should be optimal, closer
to the values I listed above. If the part is very complex and its area
is difficult to calculate, increase the current by 5-10% every half hour
and monitor the progress. If it speeds up and there are no artifacts,
repeat, but do not increase it too quickly or too much and check
constantly, especially during the first attempts.
12. Process. The gun was copper-plated for over 6 hours, and the small parts for up to 5 hours. In the photo above, you can see how the copper gradually crept up onto the parts, covering them. However, one hinge (3rd from the left) and one middle rim didn't even begin to coat for almost 3 hours... I was beginning to think there was a gap in the graphite coating, but after 3 hours, these parts finally started to coat. Apparently, the copper bypassed the gap, or other parts absorbed all the current. So don't panic if you don't see anything. Hold a flashlight to the wall, and you'll see the copper growing.
Unfortunately, I forgot to rotate the coin in the holder, and as the character in "Pirates of the Caribbean" said, the coin became part of the ship. It was firmly attached to the holder. To prevent this, you need to rotate it every couple of hours.
This result could have been achieved faster, but I decided to try the slower method to achieve the most even layer. Now, we'll speed things up.
14. Filter. Here's a clear example of why a filter is needed. After use, the plates should be rinsed with running water and the filter washed. Before the next use, the plates should be treated with steel wool.
15. Layer thickness. Depending on the copper plating time (in my case, it was 6 hours of layer growth and +24 hours of layer buildup), you can build up the thickness of a sheet of paper—0.1 mm or 100 microns. While this may seem like very little, this thickness isn't really necessary. 50-60 microns is sufficient to safely grind and polish the part. And at a thickness of 60-100 microns, the part's strength is simply incredible, but the burrs increase and the geometry changes. More on this later.
16. I forgot to remove the copper from the water after rinsing, and it turned out like this. The colors are simply stunning...
But that's not a problem. It's just oxide, and it can be easily removed with steel wool. But there's a catch, and I'll explain it in detail below!
17. Artifacts. Waves or burrs, as I understand it, appear more often on the top, so it's better to place the part upside down. To prevent this, stir the solution or rotate the part regularly. Pimples or growths (like coral) are caused by high current. (I try to avoid this. It's better to go slower, but then there won't be any extra work when sanding.) But even if these appear, copper sands perfectly with sandpaper and polishes with steel wool (but I'll explain more about polishing below!)
In this way, as you can see, you can copper plate any metal, from jewelry to coins.
For comparison, the original 1 hryvnia coin is on the left, and the
copper-plated one is on the right. If you'd like, I'll coat it with a
green patina to achieve an antique look; more on that later.
18. Strength. I tested parts with a 0.1mm layer thickness. They were so stiff in bending that they couldn't be compared to regular copper. I could almost reach a 90-degree angle before the part broke. But bending at 50-70 degrees was completely straightforward. I tested the tear-off strength of a rim of similar thickness. It's a shame I didn't have one with the ring raised, so I could have tested it more accurately. Even so, it's clear that the rim easily withstood over 4 kilograms and broke at 5. I'm sure it would have withstood even more if it hadn't bent from a "flat" position. But then, the glued joint might not have held up. It could have simply torn away from the hole (wood or glue). But even if we take this figure into account, I'm not sure most of you have a model that weighs even as much as this rim alone. Therefore, I think, for those who want strength (although I am sure that half will be more than enough) - you can safely build up 100 microns, but there is one But!
In the photo: on the left is a 0.4 mm thick plastic part. In the center is a 50 micron copper layer, on the right is a 100 micron layer. (*Painted plastic rim).
If strength and thickness are required, then this should be calculated as much as possible during modeling and taken into account when constructing the geometry; this will avoid problems. If the layer thickness is not too thick and extreme strength is not required, a 30-40 micron layer can be used - that's a third of a sheet of paper - which, with ideal geometry and minimal sanding, is more than sufficient.
The geometry of parts can be refined experimentally. In a 3D program, you can model dozens of variations in size and shape in just a few minutes. Print hundreds of parts at once and then copper-plated them in the same quantity, then choose the best ones. You can make them slightly uneven, with different positions, to achieve maximum realism... but it's impossible to manually produce the same number in such a short time using the standard method, that's a fact.
I'm already preparing a second set of tests to demonstrate different conditions, how to and how not to copper-plated them. I also plan to test copper varnish (if I buy it). It's even more expensive and harder to find than graphite. But it works much faster, is more predictable, and the copper grows not from the holders, but over the entire surface.
Naturally, I also plan to show you how to blacken it all. This process also involves some tricks, as the cannons need to be blackened using one method to make them look like cast iron. And everything else - anchors, rims, hinges - should be blackened using a different method to make them look like forged steel.
Test #2
In this post, I'll discuss common mistakes and the benefits they offer for further analysis before creating the desired result.
20. Holders. The ideal method turned out to be drilling holes and fixing (without glue) wire of the same diameter, and copper wire, into them! After copper plating, these holders can be cut off with wire cutters, and the end will be as copper as the rest of the surface, and after sanding, you won't find the missing piece. This is correct, but the quantity is more than sufficient – two, as it turns out, are more than enough for this size. They can be placed at the points of contact with the gun carriage. These same holders can also be left in place and will hold the gun on the carriage if you pre-drill holes in it.
21. Growth rate. The more metal growth points, the faster the entire part will be coated with copper and begin to build up a layer. This is theoretically possible, but! The more holders, the more metal in the solution, and this metal (the holders) increases the overall surface area. But the worst thing is that this metal (the holders) is coated with copper faster and absorbs current better than graphite. So, this statement isn't entirely true. In this case, it would have been possible to make 4-5 of them in different places and not press them against the figure.
22. Mistakes. For the experiment this time, I did everything wrong! Firstly, the biggest mistake was not waiting for the graphite spray to dry completely. Last time, it took almost 3 hours, and this time no more than half an hour. I forgot about it and then applied this experience in the future. Also, I installed one large figure, a couple of medium ones, and many small ones at the same time (upside down in the photo). I also placed the small ones practically on the surface (high up, where there is little copper in the solution) and on the side (not in the plane of the entire composition, this is wrong). And what's the problem? The huge number of holders on the large figure consumed a lot of current, leaving none for the small details. Plus, a lot of holders ended up in the solution, which increased the already large area. Plus, the large figure has a very complex shape, which is very difficult to calculate by area. And as a result, I initially gave insufficient current - 0.1 A, which is very little for this composition (especially for graphite that has not dried completely). Unfortunately, I wasn't able to check earlier, but after 4.5 hours, there was practically no result. After that, I realized I could now experiment with doing everything the wrong way, to clearly demonstrate all the errors. I set the voltage overnight to 0.2A, which is also too low. And the result was predictable. The graphite failed to coat properly, and during this time, the wire and the already coated areas were drawing a significant amount of current and copper. Ultimately, I reversed the process and gradually increased the voltage to 0.6A, which worsened the situation, which is exactly what I needed to clearly demonstrate all the errors, both the low current at the beginning and the high current at the end.
23. Corals or Sugar. Let's recap why this happened. What was
wrong: 1) the graphite should have been completely dry from the start!
2) too many holders, which absorbed all the current, 3) insufficient
current at the beginning, 4) too much current at the end. The result is a
huge layer, loss of texture and geometry (if there are uncovered
areas), a brittle coating, and I won't even mention the surface
roughness. BUT, I did some experiments with guns and will talk about
them later, so all this was worth it. I'll talk about this later when I
talk about blackening.
I wanted to clarify again that copper deposited on graphite that hasn't
dried (less than 2-4 hours) is very, very brittle. It breaks easily when
bent and is definitely not suitable for rims (although roughness is
also unacceptable for them). This is all because the copper didn't
adhere to all of the graphite, but to the particles on the surface.
Where the other particles (which should leave the surface after a couple
of hours) are, it doesn't adhere, and this surface repeats itself
higher and higher with each layer, forming crystals and producing a
minimal copper density.
24. Consumption. Not counting my rigorous, multi-hour experiment, the solution loss due to evaporation and filtration (sedimentation) is about 3-5 mm across the height of this container. And after two applications, the copper plate has shrunk by half. But that's a measurement from the bottom. It's thicker in the middle and closer to the surface.
The results of this and subsequent tests will be at the end of the blackening section, allowing for a clear comparison of all the options.
Test #3
Since it became known that poorly dried graphite causes "sugar" or "coral" granules to form on the surface, I wanted to take advantage of this to roughen the guns. After the first experiment, the guns were too smooth and shiny (but perhaps I simply overdid it with the 0000+ steel wool polishing, while 000 would have been sufficient). I'll cover this in detail in the blackening section.
So, a new approach:
26. Preparation. I lightly sanded the surface of the plastic, removing the texture from the printing, only on flat areas. I did this because I wanted to apply a thin layer and didn't want the texture to be visible... but getting ahead of myself, I'll say it was still slightly visible. So, too thin a layer isn't good either, so either prepare the surface more thoroughly or apply a larger layer.
27. Fixation. I made two holders for each piece slightly longer than 4 cm. I didn't combine them into a single link and minimized the amount of metal. As I said, I drilled a hole and fixed copper wire into it without glue. When cutting, the end merges with the surface, and after polishing, this area is invisible. But it's still better to do this from below or, as I plan, in the gun holder where it attaches to the gun carriage.
I'll also post the results in the next post, showing them and indicating which test resulted in which.
Test #4
This time, I also deliberately underdried the graphite to achieve a rough surface.
This time, I chalked a 55mm anchor and a 37mm gun. I minimized the
holders. I started at 0.01 A/cm² because I didn't need to worry about
crystals forming in the uncured graphite (I wanted them anyway) or about
brittleness (strength isn't as important here). After an hour, I
lowered it to 0.006 A/cm² to prevent crystal formation and keep
everything under control. After four hours, I increased it to 0.007
A/cm², and after another three, I increased it to 0.01 A/cm². I rotated
the parts so that the spots that hadn't yet closed were closer to the
plates. There were three of these, each 5mm thick. I'll leave them
overnight to build up a layer at a low current of 0.007 A/cm².
I have one final experiment planned – one aimed at replicating the
overall result, or rather the one I'm interested in, to ensure
repeatability. After this, I will draw conclusions and show all the
results, and most importantly, this is the result after blackening,
since this is what everything was done for.
If you think you don't understand anything, you're not imagining it. You
just have to try, and then everything will fall into place. There's not
much that's difficult here. You just need to understand the principle,
and you can achieve any result, and you can choose the one that suits
you best. Good luck.
...to be continued.
P.S. A small addition. I would like to emphasize the importance of stirring the solution..
31. Shielding. If the solution isn't stirred, copper will settle on the areas closest to the plates. And if you have a spot to coat that's surrounded by other surfaces that are already coated, they will act as a shield and absorb the copper.
32. Magnetic mixer with heating. I've already ordered one, and
I'll let you know my impressions as soon as I try it. I hope the results
will be predictable, much faster, and more even.
UPD: I don't recommend this type of stirrer! It creates a very large vortex that sucks air all the way to the bottom of the container, making it unusable for this purpose.
33. Structure. When copper is deposited on graphite that is not completely dry, and even with high current, its surface and the layer itself become loose and very brittle. In a normal state, on pure metal, it adheres as a single unit. On fully dried graphite, with low current, copper also adheres very tightly; its structure is strong and it can bend within the strength limits of the underlying material.
Results!
While I wait for a magnetic stirrer for new experiments, I'll show you the results from the ones I've already done.
Left (1a) and center (1b) - Test #1.
The graphite was completely dry (3 hours). Therefore, the surface was initially smooth, dense, and very strong. Current 0.006-0.007 A/cm². The layer thickness was greater than 80-100 microns. The coating time was 6 hours for buildup and 24 hours for layer growth. Left - polished with 000 steel wool (which was sufficient). Center - polished with 0000+ steel wool, which produced a high shine, which is excessive for cast iron.
Right (2) - Test #2.
The graphite had not had time to dry, which is why "sugar" formed on the surface. Because of this, the surface is loose and weak. The current was too high (for the purposes of the experiment). The layer thickness was too large (not needed). Polished with 000 steel wool. A rough surface was intentionally left to imitate cast iron (but it was excessive).
Conclusion. (1a) would likely have been acceptable if I hadn't overdone the polishing, so I already applied the blackening to option (1b). I also didn't like the excessive shine and gloss. It's more suitable for forged steel (anchors, rims, hinges) than cast iron. I'll try to replicate result (1a) in test #5. Result (2) was close to what I wanted, but the crystals were too large, so I tried to replicate it in test #2 with smaller crystals.
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The graphite was intentionally left uncured to achieve a sugar-coated surface effect, but due to the low current, the crystals are not large (which is what was intended to simulate cast iron). The current was 0.009-0.01 A/cm². The layer thickness is minimal; there are some areas where the print texture is visible (this was done for the experiment). The buildup time was 4 hours, and the layer growth time was 10 hours.
Left (3a) - immediately after copper plating. (3b) Right - after sanding with 000-grit steel wool only. Anchor (3) - sanded with 600-grit sandpaper and then with 000-grit steel wool for smoothness and a forged steel effect. There are streaks on the guns. I intentionally created an uneven surface to demonstrate that the graphite layer must be uniform and even, otherwise there will be ripples.
(3a) I also polished it with 000 steel wool and after that I put it back in the bath for 15 minutes to copperize.
I did the same with (3b), but I set it to re-copper for 2 hours, just like with anchor (3).
After that I got a surface like this, almost the same as immediately after test #1.
Conclusion. The quickly grown sugar surface turned out well for the guns, but the anchor required some effort to polish. Re-coppering the polished surface very effectively removes polishing scratches and dulls the shine and gloss. But getting to the bottom of it, the top layer of re-copper plating must be removed before blackening, as it is brittle and susceptible to scratches. Light polishing removes this layer, and after blackening, the surface is resistant to friction. This time, the layer is much thinner, and this is noticeable in the geometry and weight.
______________
Test #4
I didn't dry the graphite thoroughly enough again, to achieve a crystalline surface (next time I'll take the opposite approach. I'll create roughness on a smooth surface mechanically). The current was 0.01-0.008 A/cm², and I actually lowered it towards the end after filling the part. Because I didn't stir it, two internal points on the armature didn't close for a long time. The parts took a total of 24 hours to copper plate (due to the low current), but we have power outages, so I don't know how long the process took overnight. The layer is thin, so it's difficult to calculate. The coating has small crystals.
(4) After copper plating, the anchor was sanded with 600-grit sandpaper and 000-grit steel wool. (4a) The cannon was sanded only with 000-grit to preserve as much roughness as possible while removing the top layer. You'll understand later why I did it this way this time.
But these aren't the final tests yet; there will be more... control tests. But conclusions have been drawn, and at the end, I'll summarize the most important points and write instructions for the best option for cast iron and forged steel... Until then, the next post will cover the most important thing... the purpose of all this copper blackening... and then the real results will appear.
Now I'll tell you how it's best to do it. Yes, I might have some issues, but the main thing is that everything works, so here's the logic of the process...
- You need to accurately calculate the entire surface area and set the current to 0.01 A per cm², no more, but it's better to lower it by 25-30% and monitor the growth. If it's very slow, increase it to 0.01 A; if you see more visible crystals, lower it.
- After coating the entire surface with copper, you need to decide whether you want cast iron or forged steel. If you want cast iron, increase it to 0.01-0.02 A and monitor the surface to avoid overdoing it. But if you want forged steel, you need to keep the current low and for many hours. This is very important for rims, where you need a strong and smooth structure.
- Place the parts so that there's space around each one, otherwise they will divide the overall solution, and the layer will lay down more slowly. - Finally, when almost the entire surface is coated with copper, but some localized areas still remain in the graphite, you need to move that area closer to the plates. And after it's coated with copper, reposition it evenly, like all the other parts.
- Don't exceed 0.03 A/cm², otherwise this will lead to corroded surfaces and brittle coatings. Better slower, more predictable, and stronger than faster and more problematic.
- If you see the structure is already closer to crystalline, and if the entire surface is already coated, it's best to reduce the current by 25-30%. This will strengthen and smooth the structure, and the crystals may not disappear completely, but they will become softer. If you're making guns, this is what you need.
- Cleanliness of the solution. This is very important. If there are debris or other particles, it can affect the layer structure.
- Stirring is very important, as is repositioning the parts. A calm environment can cause the process to be slow, unpredictable, or even stop completely.
- If you need strong rims and hinges, use 0.006A for starters and 0.005A after coating.
If you need large wrought iron (anchors), use 0.008 - 0.006A.
If you need cannons (cast iron), use 0.01 - 0.008A for smoothing crystals.
* I might change some of my conclusions after new experiments, so this list is not final!
Copper Blackening (After Galvanization, but this is also applicable to ordinary copper).
I blacken with the well-known Brass Black by Birchwood Casey (new bottle design).
Since it's not cheap, there are a couple of ways to use it efficiently.
During blackening, you should constantly brush the surface of the part
with a regular brush to remove any residue. This will interfere with the
process, and the blackening will be superficial, insufficient, and not
very durable. Be careful, as the blackening is weak during the process,
and the metal part of the brush and other parts can scratch it. After
finishing, rinse the parts with running water and dry them with a soft
cloth or cotton cloth. But...
...if the exposure wasn't long enough, you can get a dark bronze effect like this (if that's what you're looking for). But if you want forged metal, you'll have to wait.
In the photo above, the right loop is dark brown, the left is black. The rims are also different colors, so you need to carefully calculate the concentration and exposure time if you're doing multiple passes to ensure all pieces are the same color.
I liked the gun better after the second test, but it's far from perfect. It's not smooth, so it doesn't have the extra shine, and the blackening is more matte and blacker on this surface. But still, there's too much roughness.
After re-coppering, but without polishing the surface before blackening, this is what we got: the anchor (3) and the cannon (3b). But as I already mentioned, this surface (which wasn't polished with 000 steel wool after copper plating) is very fragile and not scratch-resistant, because...
... I removed the blackening with 000 steel wool...
...and repeated the blackening (3) and (3b). This time the surface was more scratch-resistant, but still somehow too light a graphite color and had a bluish tint.
And since I got the same result on the large anchor (4) and on the gun (4a) I decided to remove the blackening with steel wool and resort to the second method of applying the blackening with explosives to achieve a deeper black.
Option 2: Apply the clean BB solution drop by drop from a syringe to a brush and rub it evenly into the part.
While I'm not sure everyone will agree with my choice, I'm giving you the opportunity to choose the color and texture you like and create the look you like.
To summarize:
(1) - very smooth surface after heavy polishing with 0000+. First, blackening with a 1:10 dilution for 17 minutes. Then, twice applying a pure BB solution and letting it dry.
(2) - very rough surface. First, blackening with a 1:10 dilution for 17 minutes. Then a second application with a 1:5 dilution, letting it dry and wiping.
(3a) - after repeated copper plating, blackening with a 1:10 dilution for several minutes and a long exposure.
(3b) (3) - after repeated copper plating for two hours, blackening was done with a 1:10 dilution and a 17-minute exposure, but the layer was weak (I previously wrote about why). Then, after removing the blackening, blackening was repeated with a 1:10 dilution for 17 minutes. This produced a good result for the anchor, but insufficient for the gun.
(4a) (4) - after repeated copper plating for two hours, the gun (4a) was blackened with a 1:10 dilution for 17 minutes, and the anchor (4) was blackened with a 1:20 dilution (since it was large and required a lot of liquid) and a 17-minute exposure, but the graphite color was not deep. Then, after removing the blackening, blackening was repeated by applying pure explosive for 10 minutes. And after this, the result is an anchor with a deep, dark graphite color and a faint sheen, while the cannon (4a) is more matte, darker, and practically sheenless.
P.S. Don't look too closely at the texture yet (some have visible imperfections and printing marks). These are just test samples, and they were made using parts that had previously been rejected.
I don't know if this happens with brass, but it can happen with copper, so be careful!
But that's not a problem—it can be removed simply by wiping with a cloth and rubbing alcohol.
*As I mentioned, a contactless stirrer isn't suitable for our purposes, as it creates a vortex that sucks air to the bottom of the container. So, I decided to create a different stirring method and simultaneously increase the capacity and the number of anodes. Let's get started...
With that, the top part of the device is ready; let's move on to the bottom:
The end result was this unit, which my wife called "The Bomb" )))))
3. Cathode.
WARNING! Be sure to let the varnish dry for at least 5 hours.
Then I bent the wire so that all the parts were equally spaced on two levels, like on a carousel. After that, I secured the supporting wire (by the way, it's 1 mm, not 0.5-0.6 mm like the others) to the terminal connected to the motor's rotation axis (which carries the negative charge). I replaced the clamp with a more unique brass one for a simple 5-cent terminal.
