Just getting ready to try electrolysis for the first time, I have a few questions: 1. Can I use electrolysis to clean up a rusty tin, without damaging the painted side, or will it remove the paint as well as the rust? 2. In the absence of soda ash (I can't seem to find it here), what is the next best electrolyte? 3. How can I set up electrolysis for zinc-coating (galvanizing) of tin? Thanks, Yonadav
OK, Yonadev - I've never used electrolysis in a stove context but I've seen it done a few times. As far as I'm aware, electrolysis will definitely remove paint from the tin because the electrolytic action takes place at the boundary of the metal and electrolyte i.e. under the paint, which lifts off as a consequence. I'm not exactly sure what you mean by 'soda ash' but (again, as far as I'm aware) the usual electrolyte used is sodium carbonate a.k.a. washing soda. That shouldn't be too difficult to obtain, I'd have thought. One caveat, though - I think in some countries, washing soda is a substance called tri-sodium phosphate (TSP) and I doubt that would behave in an electrolysis bath the same way as sodium carbonate. As for your third question, I haven't a clue - sorry!
I'll backup David. 1. It is a great way to remove paint, even if you don't want to. 2. Soda ash is sodium carbonate, also known as washing soda. But you can use sodium bicarbonate (baking soda), it is slightly alkaline so do not use much. A couple table spoons of either in a few gallons of water is plenty. Much more than that and you start to heat the water. 3. No experience, but I understand it is not a "home project" due to the chemicals required to do it correctly.
I was thinking about sodium hydrogen carbonate (formerly sodium bicarbonate - in the UK, anyway) as an electrolyte. I was wondering if the hydrogen ions, when discharged at the cathode, wouldn't be released as hydrogen gas. That would present a risk of explosion/fire if adequate ventilation wasn't allowed. I must stress I'm just wondering here - I don't know for sure and I may be completely wrong. However, in the interests of safety, I offer it as a possibility and, hopefully, someone who knows will make us aware, one way or the other. Amazing what I've forgotten in the 15 years since I last taught Sciences...
Thanks, all. Well, I'll have to figure out some other way of removing the rust from the insides of those beautiful tin cans. (I don't know why, but even the cans with bright and shiny outside paint have tons of rust inside.) As to the electrolyte, sodium carbonate (= soda ash, = washing soda) is not available on the retail market in Israel - I have no idea why. I will try sodium bicarbonate (= baking soda). The hydrogen discharge is no problem, as I'm doing it outdoors. I'd still love to find a DIY way of coating tin with either zinc or brass / copper, to deter further rusting. (I have been coating steel with brass by simply heating the steel to around 300 degrees C, and then brushing it with a brass brush, but this will not work on tin.) Yonadav
Both H2 and O2 will be generated in the electrolysis process; it won't matter much which electrolytes one uses since the source of the gas is water being oxidized to O2 + H+ at one electrode, and H+ is reduced to H2 at the other electrode. Not too much danger unless you were to cover the bath with plastic cover or something like that. Then the gasses could build up and that might be exciting.
Hi Yonadav Good on you mate for trying this technique. !. Electrolysis will, as has been said, strip everything off. Especially paint. 2. I've always used TSP with no issues. I wonder if powdered laundry soap would function as well.???? 3. I don't know. But, here are some thoughts that I've not yet had the time to explore myself. Phosphoric acid will convert rust to an inert non-rusting compound. Kerophile mentions this in his four-part "how-to" on fettling. I've used it on iron and steel to great result. I wonder if one could do "touch-ups" on painted tin interiors? What effect would it have on the remaining plating? Also, I know that there is a cold galvanizing spray in rattle cans available through automotive supply shops (I saw it at Auto Zone here in the States.) I have seen welders apply this spray to areas of galvanized tube that they've just finished welding. The welding process burns off the galvanizing in a localized area. The cold galvanizing spray restores the look of the material and seems to hold up nearly as well as the original electro-galvanizing over time. Raft frames are commonly treated this way and mine show great results (and they're in water a lot). Perhaps a little careful experimentation with proper masking on some "less critical" tins might serve to determine if these ideas are hooey or gold. Others may have more info than I on these ideas. Good luck. Best, Gary
I use this little kit for small jobs.With the brush and anode you can plate very small areas. This company will not ship out of the US so I would shop your area of the world. http://www.eastwood.com/ew-electroplating-system-tin-zinc.html Dan
Hey All, In the past I tried electrolysis and even with sodium bicarbonate. No that much gas emission occured to be concerned. Even you cannot feel it. It looks just a small boiling view. Meanwhile let me tell you that I am working for a soda ash producing company in Turkiye. I can send you any type and any amount of sodium bicarbonate how ever am not sure whether you can get it. As you would know soda ash looks very similar to cocaine. No country would accept any cargo containing undefined material...
Progress report: I tried sodium bicarbonate (baking soda) as electrolyte, and it seems to do the job - current is flowing, bubbles form on the item being treated, and the water becomes murky brownish. Rust is coming off. I hope to have some "before" and "after" photos tomorrow. Sefa - thanks for the offer for soda ash, but I'm afraid to try importing it - it might get me into customs' black list or worse. I guess I'll stick with the bicarbonate, and perhaps try some cheap washing powder. Gary - I do use the "cold galvanize" paint spray after welding, but it has a rough look, and I don't know if it will survive on the inside of an optimus 80 tin. Yonadav
Progress report - part 2: The electrolysis with sodium bicarbonate did take off considerable amounts of rust and other stuff (it was all in the murky liquid), but a layer of rust remained on the treated item. Here is a sample "before": and "after" about 12 hours of electrolysis: I then decided to try the other chemical I had on hand as electrolyte, and that is (not surprising) my favorite citric acid (that I use for soaking brass items). I was amazed to find it was doing wonders. I ran the electrolysis in citric acid solution for 30 minutes. It quickly revealed a "virgin" metallic layer on the treated item, while the liquid remains clear. Here is a "before": And this is "after" 12 hours in sodium bicarbonate, and then 30 minutes in citric acid (with current flowing through both): The sodium bicarbonate phase did very little, and most of the rust came off during the citric acid phase. Can some of you, with more chemistry background then mine, provide the theoretical explanation? Yonadav
I can't give you any theoretical cleverness on the operation, but i can say Citric acid baths are not just for brass. I have used it with great resuts on tins and steel.
