Safer electroplating solution 3
For the electroplating solution to work, the surface must be prepared properly.
Dan Gelbarts' suggests using AJAX for surface prep, which is working great.
However, in many cases not the whole surface can be cleaned in that way because of out-of-reach holes, etc. So we need a surface preparation that passes the water break test, but does not rely on mechanical action. In industry, sodium hydroxide is a common degreasing agent, but I don't have very easy access to it and anyway it is very caustic in deed. Lets try some alternatives.
Experiment 1: Degrease with washing soda
I took a steel parallel, still covered with the thick gunk it gets shipped with and put it into a solution of
50g of washing soda
750ml of water
This was done agitating with a stirring bar and the beginning temperature was 80C, but the solution was not actively heated so the temperature dropped over time.
16:23 : start
16:38 : totally ineffective.
Experiment 2: add laundry detergent
16:40 : add 25ml Gain liquid laundry detergent
16:55 : ~95% water break pass.
Experiment 3: Repeat with just the laundry detergent
The setup is just like experiment 1, but the washing soda is substituted with 25 ml Gain detergent.
17:03 : start
17:19 : fails water break, but lets run this as long as the combined time of experiment 2 and 3 to be sure.
17:35 : still fails water break test. There are many small black spots visible. The can be scraped off by fingernail. The spots are only on one side of the parallel - the side towards the center of the beaker. Adding 50g of washing soda.
17:49 : passes water break test in most areas, but not all. Black spots are still there.
So it seems very likely that the combination of the two cleaners works better than each alone.
Experiment 4: Use ultrasonic cleaner with solution
I have an ultrasonic cleaner and it should speed up the action of the cleaning solution and help in the treatment of irregular shaped samples. So here I submerge another parallel and check if the ultrasonic cleaner does in fact speed up the process. The temperature was 80C as before, but no heating was performed during the cleaning process.
After 180s : Almost everywhere water break test pass.
After 360s : Water break pass everywhere.
Well, I am not sure if we see a speed up, but it certainly does not hurt the process...
Ok, now that we seem to have a process in place with relatively safe chemicals, lets try to plate a 1-2-3 block first with copper, and then with nickel.
Here the block without its wrapping but with whatever gunk it had for corrosion protection:
Step 1: submerge 1-2-3 block in Gain-washing soda cleaning solution to degrease it. 480 seconds in ultrasonic bath. Starting temperature 80C.
Lots of gunk came off:
Step 2: The 1-2-3 block has a lot of black oxide on the inside from the heat treatment, and we have to remove that before plating with copper. Vinegar is very good at removing this oxide, so we quickly dip the 1-2-3 block in water to remove the cleaning solution and then submerge it in vinegar in an ultrasonic bath for 360 seconds.
The vinegar took care of the black oxide in short order:
Step 3: We use the standard plating bath with a copper anode.
18:40 : Start. the anode is making crisping noises. Maybe I should use a large area anode next time. Temp=60C. Heater on. Current 0.85A. The block gets covered pretty quickly by a grey coating, independent of whether current is flowing. I saw this before in previous plating experiments. The bath is very aggressive towards regular steel.
19:24 : Block mostly covered in matte copper. Turned off stirring because a lot of anode debris was settling on the block. Without stirring the debris settles and I was able to shake it off the block. Moving the block every few minutes to try and equalize the average current density.
19:30 : Current down to 0.7A at max supply voltage. Dialing constant current control down to 0.4A
19:55 : Switch to new bath with nickel anode. CC setting 0.45A
20:25 : Color building up in new solution, but very slowly. Increase current to 1A
21:05 : No progress. Increase current to 2A
22:00 : Turn off heater. Reduce current to 0.5A. Solution is milky green.
23:00 : off. Store block in water bath over night.
07:57 : continue. 2A. 23C
09:03 : Temp=53C. Large area of black coating on the side of the block towards the electrode
10:00 : stop. Store block in water bath
11:39 : continue. Temp=23C. 2A. Heater on. Will go back to setpoint of 53C.
14:40 : stop. result: nice matte gray coating throughout, including in the holes.
Here the plated block next to an unplated one.