Reduce foam from cell?

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duhiliketolick

Member
Joined
May 28, 2008
Messages
11
Location
SC
Just recently obtained a piece of real copper flashing and made a small pan. I put a processor on to it in the cell after a few minutes a large foam over flow. Does any one know what are the causes of it to be greater? (did a proc with just a clamp and minor foam,barely noticeable). Is there a way to reduce the amount of foam or should I install an over flow system? :roll:

Thank you for answering eagle 2. I was using a car charger, tested it this morning and it was reading a little over 9 volts. First problem solved now to create a resistor to reduce it to 3-5 volts.

Thank you aurumshin it is black sulfuric acid Iwill try to find a clear. I have also switched to a multi voltage pack from radio shack. With 4.5 volts it is a manageable foam but is seeming to take a long time (processer has been in over an hour with not a pins stripped (I checked and had some none touching pins) Clean dish has been washed/rinsed in plain water numerous times.
 
I think your sulfuric acid is too dilute and what color of sulfuric acid black. black sulfuric acid do many problems in your cell .use color less or yellow sulfuric acid.
 
I have run the sulfuric for 1000s of hours and don't remember one instance where I got any excessive foam. The fizzing above the parts will create very small amounts of foam but it immediately goes away.

Did you clean the vessel with soap? Traces of soap can cause foaming. It doesn't take much. I've had this happen when I precipitated Au from AR. As a result, I don't clean vessels with soap unless oils are present. When I do use soap, I rinse the vessel many times with hot water.

As aurumshin mentioned, weak sulfuric could create foaming due to the excessive amount of current that would be drawn.

If you're using sulfuric drain cleaner, maybe the added buffers are creating the foam.

If you are using concentrated sulfuric acid (96%+), with no more than 5 - 10%, by volume, of water added, I see no problem with using 9 volts, if you don't try to strip too many parts at one time. I used to use 12 volts with no problems, assuming I didn't overload the tank with parts and, therefore, draw excessively large amounts of current at the beginning. With the right strength sulfuric, the parts will strip quickly and the amperage will soon drop to zero.

If you are doing things right and you still get foam, you might try using a deeper tank to provide room for the foam. You might also try spraying just a mist of water on the foam from an atomizer spray bottle - that should temporarily kill the foam - I've never tried it on sulfuric, but I used it often with nitric or aqua regia. Don't use a stream of water or it will dilute the sulfuric, heat up, and could cause the sulfuric to splatter on you. I would only use the mist if the foam is in danger of going over the top of the vessel.

A battery charger is, by far, not the best thing to use. I know they are expensive when new, but a variable, one knob, plating rectifier with both amp and volt meters is the best. My brother has an ancient battery charger that is made in this way. If you are hooked up, turning up the knob will increase both V and A together. At the start, I adjusted the amps to about 10% below the limit of the rectifier - too much amperage would blow the fuse. The amount of voltage would depend on the surface area of the gold I was stripping - it usually started about 3 or 4 volts. As the gold started stripping, the amps went down and the voltage went up. I increased the amps again to near max. At some point, the voltage was pegged and I just left it alone until the amps read zero. Using this method, average gold plating was completely stripped in a minute or three.
 
goldsilverpro said:
Using this method, average gold plating was completely stripped in a minute or three.
Click to expand...

:shock: :shock: :shock:

whew....

Sir, how many grams is the yield for that 1-3 minutes?

was thinking about using Copper Sulphate method to take copper away from gold.
now heavily considering the sulfuric cell to take away gold from the copper.

:shock:
 
Higashi said:
goldsilverpro said:
Using this method, average gold plating was completely stripped in a minute or three.
Click to expand...

:shock: :shock: :shock:

whew....

Sir, how many grams is the yield for that 1-3 minutes?

was thinking about using Copper Sulphate method to take copper away from gold.
now heavily considering the sulfuric cell to take away gold from the copper.

:shock:
Click to expand...
I have no idea of the relationship between yield and time in this solution. This had no importance. I continually adjusted the V/A. At first, the amps were quite high and the voltage was very low. As the parts stripped, the amps decreased. I kept raising the voltage, which also brought up the amps. The amps kept decreasing and I kept raising the voltage. When the current decreased to zero (with maximum voltage - say 12-15V), the parts were completely stripped. I didn't even have to look at them - they were always completely stripped at this point. It took just a few minutes for regular plating and 15-20 minutes for thick gold braze.

However, I always used spring contact plating racks (which I always fabricated myself) or a plastic tumbler with internal electrical contacts (which I bought ready-made). I mainly ran CPUs (with the lids and chips removed by melting the brazes) on the racks - with some CPUs, I had 3 or 4 spring contacts. I ran mainly pins and CPU lids in the tumbler. Nothing was ever put into a stagnant basket or in a pile - bad ideas, in my estimation. The way I ran the parts, almost every part got about the same amount of current applied to it. Of course, I had a big 50 gal tank. I could apply about as much amperage (I had a 250 A rectifier) as I wanted without the solution getting too hot - very important. With these tiny tanks you guys are using, you have to keep the amperage very low in order to prevent overheating - I wouldn't exceed 10 amps per gallon - maybe even 5A max/gal). The voltage isn't that important. The amperage is what does the work. The volts just push the amps.

I realize that I had a large professional setup and you guys are trying to make do with toy cells. Were I you, I would try to devise some sort of non-metallic tumbler, with internal contacts, for things like pins. I know this is possible but I haven't seen a good design yet. Also, consider making racks for some of the larger parts. For my large cells, I made racks with 1/4" square brass rod, with stainless steel piano wire spring contacts. I threaded holes in the brass and attached the spring wires with stainless screws.

If I were making a hobbyist cell for myself, it would be at least 2 or 3 gallons. I don't like crowding a lot of stuff into a tiny cell, as it makes things so much more difficult.
 
Really nice post, Pro. Thank you for all that experience sharing. Only one thing I might repeat that I mentioned in a previous post, you can easily adapt an old computer power supply for use in the cell. It is already regulated at 5 volts and the amps available from one rated 300- 500 watts, would be about 50 - 90 amps!

Al
 
eagle2 said:
Really nice post, Pro. Thank you for all that experience sharing. Only one thing I might repeat that I mentioned in a previous post, you can easily adapt an old computer power supply for use in the cell. It is already regulated at 5 volts and the amps available from one rated 300- 500 watts, would be about 50 - 90 amps!

Al
Click to expand...

yep... it's the best power source out there for tiny budget.

unless for the top specs, one get around 14A-40A per channel, different amperage on different voltage channel.

but it's cheapest way to get there. built a few op-amp/regulator/power-transistor power supply only to finally scrap them and mod the ATX PSU.

it's darn cheap.
 
You can even enhance your cheap psu with a cheap ammeter, made from any old gauge. Just make sure the shunt is a low enough value so the full scale reading does not over peg the meter and burn it out. It does not have to be accurate at all. The parts are stripped when the gauge reading falls to zero or near zero. 8)

Al
 
eagle2 said:
You can even enhance your cheap psu with a cheap ammeter, made from any old gauge. Just make sure the shunt is a low enough value so the full scale reading does not over peg the meter and burn it out. It does not have to be accurate at all. The parts are stripped when the gauge reading falls to zero or near zero. 8)

Al
Click to expand...

some uber cool ammeter : http://cgi.ebay.com/3-1-2-BLUE-DC-200A-LCD-Digital-AMP-Panel-Meter-Ammeter-/220595840895?pt=LH_DefaultDomain_0
 

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