Introduction: Copper Electroforming on 3d Printed PLA/ABS Objects
I would like to explain briefly my first steps in Electroforming with 3d Printed Objects. I hope it helps you. I love to print and test new materials, looking for new usages of 3d printing. I think 3d printing has more to give than printing action figures, spinners and, ocasionally, product prototypes. This technique can be used for jewerly, medals, electronics... or just because we can do it.
This is the result of googling and reading some useful articles, and I think I've got an easy way to cover 3d printed stuff with copper.
I'm not gonna get much technical, because I am not a chemical technician. And also I am from Argentina, english is not my first language, so please tell me if I write something wrong or incomprehensible.
Materials for making the Conductive Ink:
+ Graphite Powder:
I bought it in 2 different places: Art Shops and Hardware Store(lubricant for locks)
+ Chloroform / Acetone
Materials for Electroforming:
+ Plastic paint bucket or Glass bowl or jar (non conductive): 1lt
+ White vinager: 1lt aprox
+ Copper Sulphate: 1/2 cup
+ Copper Metal: Wires/Copper Tube
+ Destilled Water: 1lt aprox
+ Safety Goggles (because safety is the number one priority!)
+ Hydrochloric acid (muriatic acid used by plumbers) (optional and dangerous!): 1 tablespoon
+ Salt (optional): a pinch
+ DC Regulable Power Supply ( Around 1 to 10 volts, 2 amperes max)
+ Polyethylene glycol (PEG: it is a laxative, ask in pharmacies) (optional, I didn't use it)
+ Multimeter (optional)
+ Air Pump for Fish tanks (optional)
Step 1: Making Plastic Condutive: Graphite Ink
The number one rule for electroforming might be: "All the things* must conduct electricity"
But the plastics are not conductive! So...
We have to make it conductive in the surface at least!
WARNING!: Acetone and Chloroform are dangerous and volatile sustances. Manipulate it with care!
Mix a spoon or tw of chloroform with graphite until get a dark gray consistency paint. This dries out very fast, so I made it in small quantities. The chloroform evaporates, and leaves the graphite and can be used again.
The chroform or the acetone dissolves a first layer of the plastic, so the graphite gets bonded by the same plastic and also smoothes the surface. Avoid touching, because the surface is soft. This makes a conductive surface all around the object.
Once dry, you can gently clean the excess of graphite with a fine steel wool.
You can test the resistance between two points in the object with a multimeter.
It is important to not to touch directly with the fingers again, because the grease of the skin can affect the surface finish. (I didn't care too much of it and I get aceptable results)
I tried graphite ink made with acrilic paint and graphite with bad results.
*When I talk about the "things" I refer to:
The positive side is: CATODE
The negative side is: ANODE
Step 2: The Blue Solution: Electrolyte
In internet we can find some already mixed electrolyte for copper plating/electroforming, but as I live in Argentina buying in other country is difficult. So I found recipes for making my own electrolyte solution in my home, with common materials that can be found in the grocery store. Other electrolytes are made with Sulfuric Acid (called battery acid) that is much much more dangerous thant vinager, so it isn't a option for doing it in home.
WARNING: The copper sulfate is poisonous. Don't touch it directly and don't mix with the same spoon, cups or tools that you use to cook. And be carrefull!.
I mixed all directly in the paint bucket:
First Heat 1 cup of Destilled Watter in the microwave (is safe because is only destilled water), once is warm add the Copper Sulfate (heat mades the solution easily). Then add 3/4 liter of White Vinager.
Until here is the basic recipe, it works!
From other articles from the internet:
- Add a pinch of salt for enhace the electric conduction. (I did it)
- Add a spoon of Muriatic Acid, I think it is for make increase the acidity. (I did it)
- Add a spoon of PEG: This is a brightener, makes the result more bright. ((I didn't do it)
It is important to not to add other metals when stiring, other metals will contaminate the solution.
Step 3: Wrap, Positioning, Shaking: Some Tips
Well, this photos are not the best examples. Or they are example of what NOT to do:
- The copper will preffer to join the wires that are connected to the negative pole, than to the graphite paint. So you will note shadows. What I do, is to change the position of the wire.
- Try not to wrap too much the piece with the wires. Just the minimum to hold and conduct the electricity to our 3d printed piece. (this is because of the shadows under the wires)
- I get better results using a air pump to shake the electrolite, I get a more even copper plating.
- Not use too much voltage (and current). Higher voltages will produce uneven and less bright plating, the copper forms "stalactites" and a brownish surface. It seems to be faster, pero in the end will get a wrost result.
- I use to remove and wash the piece after 1 hour. Then I apply other coat of graphite paint, re wrap the piece and summerge it other hour or so.
- Take care of the wires of the positive side, it will be disolved as the copper tube.
- I think a baking soda/sodium bicarbonate bath after the electroforming process will neutralice the acid of the vinager and stop the oxidation of the copper.
- After the electroforming process I use to brush with a steel wool or sand paper (300grit to 600 grit). A Dremel with sanding disc or wire brush can be usefull, but is too powerfull, so take care to not peel out all the copper.
I will add more while I get experience in this process...
Step 4: A Lot of Wires: Wiring
Starting from the battery (in my case a dc-dc):
- The positive contact goes to the copper tube sumerged in the electrolyte.
- (If you have a multimeter to measure the current, it goes in serie. So the red probe goes to the positive contact of the batter and the black probe to a wire that connects to the copper tube)
- The negative contact of the battery goes to the wire in which is wrapped the 3d printed part.
- Use a low voltage, around 1 or 2 volts.
- The current will increase until it stabilizes, and try to mantein close to 1A.
- I read that it is a good practice to connect all the parts before sumerge the piece in the electrolyte.
- Once you sumerge it, you will notice that the multimeter will start to show the current, at first it will be low (0.5A) and with the time it will be increased. So as I say earlier, do not put the voltage too high.
Follow the schematics that I found:
Step 5: Try and Fail: Repeat
If you didn't success, don't worry, start again, and repeat.
These videos are really helpfull and a good explication:
Step 6: Polishing and Sanding: Postprocessing
I've tested some ideas:
- A bath of baking soda to neutralize the vinager and stop oxidating.
- Brush it with a Steel Wool
- Water Sanding from 300grit to 600 grit (not much)
- Finish with metal polisher paste and a cotton rag.
- Dremel (in low speed, because it's a PLA piece and you must avoid heating it):
- Wire Brush
- Polishing with paste