Removing rust and scale

Hi All,

We recently had quite a few postings in another sub forum on the removing of rust and scale from old car/truck parts. I asked the question as to whether adding a current to a molasses bath achieves anything?

I had an old cast iron bellhousing stewing up in a plastic tub, pretty strong solution, did wonders but I think it had a lot more to do with being left out in the sun over a couple of stinking hot days. Had to keep topping up the solution as evaporation kept taking it's toll. Has anyone ever introduced a current to a molasses bath? If so, did it make any noticeable difference?
There were also quite a few ideas thrown up about using electrolysis and washing soda. Going by Swishy's wiring diagram, if I have this right, the battery is only there to stabilise the current, correct? So, if you are pumping say, 4 or 5 amps with a small battery charger firstly into the battery, (some other forums are saying the battery itself is not all that critical, only has to regulate the amperage) and then into the washing soda solution via the anode and cathode. As long as you don't use stainless steel (apparently it causes some sort of reaction).
I still have a few parts I want to clean up, so will try either the molasses or the washing soda/ electrolysis first. Have tried Hydrochloric acid and it's too savage on the parts, plus just about gassed myself in the process as well as coating all my tools and half the garage with a fine patina of rust! And, too hard to get rid of, local tip won't touch it! Last lot I had to wait for the annual dangerous goods roundup to be rid of it, along with enough out of date cleaners, solutions, potions, medications, to poison everything within a 100 mile radius. Just as I never had a fire here, would have gone off like a nuke!

Anyone got any comments re giving molasses a belt of current? If it wasn't in a plastic bath, I'd either light a fire under it (don't know how the solution would go in a metal tub) or keep my eye out for one of those old immersion heating elements that we all had back in the day when we boiled the copper in the back yard. Probably wouldn't be allowed to use one these days, even if you could find one! Last time I used one was I dressed a piglet out in mum's copper one Xmas. Cannot for the life of me work out why she went off her brain! May have had a bit to do with the old man coming home from work and finding a couple of inches of bristles in his beloved copper. Didn't have much of a sense of humour those days.
Dave.
Oh, and all the best to everyone for the silly season!

Dave, they are two entirely different processes. I wouldn't try to cross them at all, unless you do a bit of experimentation first. If it goes wrong, you lose the parts you're trying to save.

I've used electrolysis extensively, very successfully. To the extent I was considering digging a hole big enough for a whole car body, but haven't yet done it. I have made pools using a timber frame and black plastic to do panels and complete doors and it works great. I never used a battery, but I did get a transformer capable of much greater output than the battery chargers and will work fairly quickly (with decent output you will see it working). You can set up multiple anode/cathode points and use more than one power source (ensure its DC). I think agitating the liquid to keep the crud moving away from the panel is more important than heating it, so perhaps a fish tank pump or similar would keep it cranking. I've never used molasses, I've heard it works well though.

Have used Citric Acid Powder quite successfully to remove rust - no fumes and relatively safe to use.

What's the procedure, Fargofan?

Just make up a solution in water? What mixture? Does it need a shot of electricity to boot her along?
Thanks, Dave

Here's a guy using Citric Acid for rust removal.

His workmanship is quite incredible. It's worth taking a day and reading the whole Thread.

his formula is right at the top of the page.

www.ozrodders.com/forum/viewtopic.php?f=2&t=20217&start=1875

I use phosphoric acid. It has plenty of bite, only attacks the rust and is reasonably safe to use. The reaction also breaks the acid down to water.

for those th@ like read n bout rust removal your info iz jist a clik away

uputstva.org/odstranjivanje_korozije.pdf

www.stovebolt.com/techtips/rust/electrolysis.pdf

www.sunnymeadcycles.com/files/Electrolytic_Rust_Removal.pdf

workshopcompanion.com/Demos/Sawdust_Sess...les/Electrolysis.pdf

www.tttg.org.au/Content/Citric%20Acid%20...l%20Instructions.pdf

cya

Quite a few vids on youtube on both methods, electrolysis and molasses. Can reactivate the molasses brew by stirring it up with a burst of compressed air.
Merry Christmas.
Cheers, Paul.

I have read some of the info linked by Swishy and decided to have a go.

I selected a gear box top off an Ansaldo, the gearbox was full of water and the parts above the waterline were very rusty, the selector rods would not move.

Before electrolysis:

I put the top into the washing soda solution overnight and connected it to a battery and charger, it was drawing about 3 amps. I put a 4 amp circuit breaker in the circuit in case I had a short circuit in the tank.

The next day I removed the gear box top, gave it a quick hot pressure wash. I used emery tape on the sliding rods near the ends where they slide in and out. I applied a bit of penetrating oil and within a couple of minutes of gentle tapping back and forth with a hammer they all freed up. It is about to go back on the box so that (hopefully) I can start the machine.

After Electrolysis