Electrolysis

[Screwdriver]

I am also in the throws of building an electrolysis cleaning tank and need a few questions answered. I am using a domestic 50 gallon water tank and lid.

I would be very grateful for any help on the following questions. Tinternet takes me around in circles.

1. Voltage, is there any benefit in increasing the voltage on a larger tank ie 12-24v?
2. Power source, apparently needs to be better supply than a PSU can manage. Is a battery charger suitable in the long term?
3. Sacrificial anode, is there a rule of thumb on sizing these or do you just hang a few lumps of steel in there? Is sheet steel better than bar or big rounds?
4. Dilution rates of the soda crystals, is there an optimum ?

Sorry for the hijack but not worth starting another thread for.

Bob

1. Increasing the voltage will increase the current flowing (amps) 1-2 amps is all you really need. More voltage works more quickly but can damage delicate parts.
2. Anything will do so long as you are confident it can supply power (say 1-2 amps) continuously without supervision and without bursting into flames.
3. Anode works best "line of sight" so you ideally want to surround the workpiece. Anything that can't "see" the anode will be reduced less efficiently (you might not notice on an overnight stew)
4. Any amount that allows 1-2 amps to flow. More electrolyte = more current, more sacrificial anode material also increases the effect as does more volts. Find a balance, 1-2 cupfulls for a big bucket is plenty.

I chose Daz because if you read the packet it contains a high proportion of sodium carbonate, you could just use sodium carbonate powder but I find the soaps can also help the process (I might be wrong about that). Don't use stainless steel for the anode, it will produce toxic waste. The process gives off hydrogen, don't leave it in a sealed room.

 

[MattF]

It shouldn't produce chlorine unless you have something funky in the powder.

 

[bigegg]

It shouldn't produce chlorine unless you have something funky in the powder.

some soap powders contain sodium hypochlorite (as a brightening agent).
this will decompose to give chlorine.

 

[Screwdriver]

It shouldn't produce chlorine unless you have something funky in the powder.

Yeah, well, it gives off something.

What am I? A chemist?

 

[Screwdriver]

It's a good point though. I see a fair few people experimenting with various mixes. Adding citric to electrolysis, using stainless steel sacrificial anodes, trying to reconstruct off-the-shelf products or come up with a new process. I do it a fair bit myself and am working on a recipe for Nitromors (the proper old school type).

It is reasonably safe so long as you do a bit of research but remembering we are all in the unusual position where we will probably weld this stuff and superheat whatever cocktail of chemicals we have cooked up. I am certainly not a chemist (!) but have amassed a huge collection of weird substances and solvents. There might not be a warning about What happens when you cook them up in a super hot plasma.

A quick glance at the MDS for my Nitromors recipe suggests one of the chemicals contains "trace phosgene". I may have to reconsider that....

 

[Hopefuldave]

A big +10 on not using stainless for the sacrificial anode - the toxic waste it produces is hexavalent Chromium, a particularly nasty chemical: neurotoxic, liver toxic, carcinogenic (even outside California). It's what turns the solution yellow...

I use graphite as the anode, leaves the solution pretty clear, doesn't grow barnacles like steel so no need for wire-brushing anodes etc. At a pinch you can use arc gouging electrodes with the copper stripped off (ferric chloride or brick acid will do it) except for an inch to solder your connections to, BUT they dissolve if left in the solution (the clay? binder) so haul them out between uses.

Don't think there's any advantage to using other than plain soda crystals, it's always worked for me, about a mugful to 5 gallons, and an old 12v start-and-charge box does 15 - 25 amps depending on the anode and work sizes - swapping the fuse for a 32A MCB (in the AC from transformer to rectifier) saves a lot of fuses for the inevitable shorts between work and anode Modern "smart" chargers won't work though, unless you put a battery in parallel with the EGBERT*

Dave H. (the other one)

*Electrolytic Gungey Bubbling Encrustation Removal Tank (TM)

 

[Hopefuldave]

A quick glance at the MDS for my Nitromors recipe suggests one of the chemicals contains "trace phosgene". I may have to reconsider that....

Methylene Chloride (the stuff that made Oldskool Nitromors work) degrades to phosgene in the presence of oxygen and ultraviolet light, as do a few other chlorinated organics - it's the reason to avoid any chlorinated solvents anywhere near welding, a few welders have died / had life-changing respiratory injuries from it...

https://envirofluid.com/articles/tetrachloroethylene-a-deadly-danger-in-brake-cleaner/
http://www.brewracingframes.com/safety-alert-brake-cleaner--phosgene-gas.html

It has the smell of new-mown grass / hay, but by the time you can smell it you're well over the safe limit

However, you can buy it by the gallon on EvilBay (I do) but keep it away from sunlight/ welding / heat if you do!

Dave H. (the other one)

 

[Screwdriver]

Yes the main ingredient is well known but useless as a paint stripper on its own because it is so volatile. I guess you could soak parts in a big enough sealed bucket but that sounds expensive, dangerous and wasteful.

I am determined to have a crack at reproducing Nitromors though. I guess the next thing I need is a suitable respirator, even though it will all be outdoors, that stuff is evil! We've all had the odd burn from it I guess and I can certainly remember the smell. Makes me shudder to think about it now, I was young and foolish then...

 

[Hopefuldave]

Yes the main ingredient is well known but useless as a paint stripper on its own because it is so volatile. I guess you could soak parts in a big enough sealed bucket but that sounds expensive, dangerous and wasteful.

I am determined to have a crack at reproducing Nitromors though. I guess the next thing I need is a suitable respirator, even though it will all be outdoors, that stuff is evil! We've all had the odd burn from it I guess and I can certainly remember the smell. Makes me shudder to think about it now, I was young and foolish then...

I buy a decent pro paint stripper and "augment" it with the methylene chloride - and use it outdoors, staying upwind!
It also works for chemical polishing a lot of plastics, park them in the vapour and it reflows the surface...

Dave H. (the other one)

 

[Screwdriver]

I buy a decent pro paint stripper and "augment" it with the methylene chloride - and use it outdoors, staying upwind!
It also works for chemical polishing a lot of plastics, park them in the vapour and it reflows the surface...

Dave H. (the other one)

Don't really want to pay twice for it, it should do what it says on the tin anyway...

But I do have a cunning plan that involves a stainless beer keg. If I make a sealed lid, I could plonk something in there and just a splash of DCM should produce enough vapour to strip whatever you put in there. Sadly that does not include much of the Bridgeport which is my next big project for stripping. The really nice thing about old school Nitromors was you could goop it onto anything and it would stick until the paint literally fell off.

 

[8ob]

Don't really want to pay twice for it, it should do what it says on the tin anyway...

But I do have a cunning plan that involves a stainless beer keg. If I make a sealed lid, I could plonk something in there and just a splash of DCM should produce enough vapour to strip whatever you put in there. Sadly that does not include much of the Bridgeport which is my next big project for stripping. The really nice thing about old school Nitromors was you could goop it onto anything and it would stick until the paint literally fell off.

I have an old Bupi hot parts washer, it uses a strong alkaline powder in the water and that removes paint. Wont derust but strips paint and degreases well, 20kg of the powder is only about £50 and you only need a few cupfulls in about 30 gallons of boiling water.

Bob

 

[Screwdriver]

I have an old Bupi hot parts washer, it uses a strong alkaline powder in the water and that removes paint. Wont derust but strips paint and degreases well, 20kg of the powder is only about £50 and you only need a few cupfulls in about 30 gallons of boiling water.

Bob

It's probably Trisodium Phosphate. I have been trying it out with mixed results. Not tried stripping paint with it yet.

 

[MattF]

I have an old Bupi hot parts washer, it uses a strong alkaline powder in the water and that removes paint. Wont derust but strips paint and degreases well, 20kg of the powder is only about £50 and you only need a few cupfulls in about 30 gallons of boiling water.

Bob

I use caustic in my electrolysis vat. Some paints will peel off, but the older lead based stuff is tenacious.

 

[Turbo]

I am also in the throws of building an electrolysis cleaning tank and need a few questions answered. I am using a domestic 50 gallon water tank and lid.

I would be very grateful for any help on the following questions. Tinternet takes me around in circles.

1. Voltage, is there any benefit in increasing the voltage on a larger tank ie 12-24v?
2. Power source, apparently needs to be better supply than a PSU can manage. Is a battery charger suitable in the long term?
3. Sacrificial anode, is there a rule of thumb on sizing these or do you just hang a few lumps of steel in there? Is sheet steel better than bar or big rounds?
4. Dilution rates of the soda crystals, is there an optimum ?

Sorry for the hijack but not worth starting another thread for.

Bob

Agree with everything so far, just add my thoughts.

I use an old 4A 12v battery charger for most things. Sometimes large items draw more than 4A so I use a large 10A 12/24v charger with a boost function.

Sometimes you will get an item with stubborn rust, maybe awkward shaped so that you don't get line of sight to the anode. In that case I use the 24v & boost setting to get things started, then switch back to 12v once it strips the rust. If you run it on high amps all the time it will eat away your anode very quickly!

As for the anodes, I've used sheet metal which is easier cleaned but wears quicker. Currently I have a mesh of rebar all around the tank & it's lasting well but a pita to clean. Next time I'll go back to sheet steel which would probably suit your tank better if it's square.

You need to keep your anodes clean, when they get coated with rust it slows the cleaning process.

A pressure washer makes cleaning your anodes & the item you are de-rusting so much easier. The crap that comes off it is horrible & will stain if you let it sit on concrete.

I have fly leads with crocodile clips mounted together on a bolt that go to the object & clip my charger lead to that. It allows me to add several connections on objects made from more than 1 piece of metal eg a vice or I can do several objects together. It also stops the charger lead getting rusty from being in the water.
I also have a fly lead connected to the anode frame so I can connect the charger outside the tank.

 

[Ed.]

I seem to be a bit confused, if the anode(+) is the part that is getting the rust from the part (-Neg) to be de-rusted then why does it get sacrificed, I would have assumed that it would get larger with all the rust adhering to it, or am I missing something?

 

[bigegg]

I seem to be a bit confused, if the anode(+) is the part that is getting the rust from the part (-Neg) to be de-rusted then why does it get sacrificed, I would have assumed that it would get larger with all the rust adhering to it, or am I missing something?

it doesnt gain any fe ions, it reacts with oxygen ions coming off the part, and bonds them to its own iron.[1]
eventually, it all turns to rust and has to be replaced. hence "sacrificial"


[1] I'm not sure if some of the iron from the sacrificial piece actual transfers the opposite way.

 

[Ed.]

Fair enough, thanks. It's something I have been meaning to try, but as yet have not done it. So a large metal tray would also serve for a once off job provided the (-) part was physically isolated as to not touch the (+) tray?

 

[bigegg]

Fair enough, thanks. It's something I have been meaning to try, but as yet have not done it. So a large metal tray would also serve for a once off job provided the (-) part was physically isolated as to not touch the (+) tray?

yes.
with the caveats that stainless steel will turn the liquid into a nasty poison. [1]
and if its too thin, it'll leak very quickly.


[1] if you've seen "erin brockovich" - the same stuff.

 

[Ed.]

No problem, I was thinking along the lines of a large plain metal tin or tray.

 

[Hopefuldave]

No problem, I was thinking along the lines of a large plain metal tin or tray.

The tray will go all lacy and leaky pretty quickly, plastic's better and any old scrap steel will do for the sacrificial anode, I usually put the parts in a plastic basket to avoid shorting it all out (thrown out at the back of the greengrocers)

Dave H. (the other one)