Thread: Rust removal by electrolysis

A lot of the modern staged chargers also have a power supply mode, I use a 10 amp Projecta switched to power supply mode for my rust bath. These type chargers can have very high outputs; unfortunately, as the amps go up so does the cost, I think my 10 amper was around $130. I also have an old low amp transformer charger I fiddled with to provide a constant 12 volt supply, it's been running my coolant pump and a few other things for years.

Hey Joe - This is exactly the same as my welder:

http://www.gumtree.com.au/s-ad/sprin...der/1086207862

Would that be an AC output or DC? Perhaps the inverter model I have would be a better choice as its definitely DC.

Re Molasses - yeah I am considering that. Bit worried about the pong though but have seen some very impressive videos online.I have been told the active ingredient is phosphoric acid- I can get hold of phosphoric acid easily...wouldnt it be less smelly and alot simpler to just make up a phosphoric acid bath?Is there anything magical about molassesbesides the acid?

Originally Posted by 19brendan81

Hey Joe - This is exactly the same as my welder:

http://www.gumtree.com.au/s-ad/sprin...der/1086207862

Would that be an AC output or DC? Perhaps the inverter model I have would be a better choice as its definitely DC.

It would also have to be a DC TIG (if your machine is a DC machine the pecs should clearly state this)

Re Molasses - yeah I am considering that. Bit worried about the pong though but have seen some very impressive videos online.I have been told the active ingredient is phosphoric acid- I can get hold of phosphoric acid easily...wouldnt it be less smelly and alot simpler to just make up a phosphoric acid bath?Is there anything magical about molassesbesides the acid?

Nope - It's definitely not just the phosphoric acid. There are around a dozen acids in molasses but more is done by a non-acidic reaction (iron chelation) than by acidic reactions.
Molasses is also very slow, depending on how rusted it was you could be looking at weeks.
On the plus side is that it is safe and it won't ruin the object.

I would not use any sort of acid bath as you will end up with a lot of pits and lumps on the surface.

The slow bit bothers me as I am impatient : )

I do have time on my side though. Will give the local stock feeds place a call to see what they have in the way of bulk molasses.

Originally Posted by 19brendan81

The slow bit bothers me as I am impatient : )

Then even electrolysis will probably not be fast enough.
Electrolysis works fastest for stuff that has a thin layer of clean rust.
For practical situations when there's oil, dirt and other stuff bound in among the rust this restricts access by the electrolyte to the rust and it can take a lot longer than one thinks.
When an area is accessible and rusted object is strong enough a quick once over with a wire brush on an angle grinder speeds things up significantly.
All this is probably why some folks crank up the V or amps - there's more bubbles so more must be happening right?
All that happens is more gas is made but there's not much more action where it's needed.

When using a passive agent like molasses I've always though some sort of stirring action in the tank might be helpful as would some heat (e.g. +30 - 40 - 50º).

It also might be useful for us to see what it is that you want to de-rust

I will have some photos on weekend - parts are a king pinfront end, 132 grey motor, steering column and steering box for an FJholden.They’ve been sitting in apaddock in wagga for decades so will need significant rust removal.I have done a front end before with a wirewheel and it was a lot of work, and it wasn’t perfect.Hence why I am looking for a more automatedprocess.

I have seen videos online of guys doing control arms etc overnight withelectrolysis which is fast enough for me.Wating a month for molasses to do the job isn’t ideal but the results seemvery good (and cheap).The local storehas it for $22 per 10L .

From my understanding with the molasses is that the chelation and bacteria go hand in hand. The bacteria need warm conditions to thrive; so nothing much happens in cool weather. 2-3 months is usually a more realistic time frame; but on the other hand I made up a batch in a blue cherry barrel with the lid on to stop evaporation. It was left in the inland sun during summer and the liquid was hot. 1 week to clean up a pair of coil springs. I find that it is best to check the progress; and if there is a buildup of black gunk on the items surface; wire brush it then wash it off well with water; then back in the brew. I have not found any problem with odour; but that could be a difference between urban and country living.

Ken

Originally Posted by 19brendan81

Hey Joe - This is exactly the same as my welder:

http://www.gumtree.com.au/s-ad/sprin...der/1086207862

Would that be an AC output or DC? Perhaps the inverter model I have would be a better choice as its definitely DC.

That Goodwell is definitely AC only. Two easy ways to tell: AC welders essentially are a big transformer - so VERY heavy. Secondly, when the sdjustment of the current is done with a movable magnetic choke, a handle that needs to be shifted in or out of the 'box', rather than a dial knob, then it is most likely an AC welder.
I suspect an inverter welder would work. Some even have a current display, which would be even better for this purpose.

Thanks Joe!



I am going to do my stuff in a plastic 200L barrel that Iwill put in the sun.Hopefully that getsthe temps up.



2 - 3 months is a dealbreaker. That’s way too long to bepractical for my purposes. The vids Ihave seen online say that 3 to 4 weeks is what is required and if my partshaven’t derusted after that I will have to electrocute them.

I have for the last two1/2 years been restoring a car and most of any movable part that was rusty has had the molasses treatment from the back axle to the all the steering ,brake parts and suspension ,although mostly done in the summer time eight days has been the longest time any thing has taken ,you must remove all grease or it wont work,
I take it out every 2-3 days give it a quick wire brush and a hose off back in the tub,don't leave them lying around after you think the rust has gone,unless you clean the black residue that is left completely off it will go rusty very quick I used 9 parts water to 1 of molasses,this is just a couple of pics to give you an Idea hope this helps.

009 cleaned with molasses.jpgIMG_1048.jpg Eddie

Originally Posted by shedhappens

molasses is a bit friendlier
http://elantrikbits.com/lotus-elan-b...ngine-de-rust/

shed

Guys

Be warned .
Be real careful with the time lines on cast iron immersed in a molasses mix .Years back we where asked to weld up a CI manifold from a Dodge Fire truck belonging to the local Rural fire brigade.

We lost track of how long the manifold was immersed and when we got back to the unit, was like sponge cake.
It was absolutely buggred after a few weeks.

Check it often.

Grahame

Firstly there are some of us on this forum who have been using electrolisis for years .

A few years ago I had an electrolsis bath going for arround 12 months continuous restoring all sorts of hand tools.

This is possibly the best article on the metod http://www.htpaa.org.au/article-electro.php

Addressing some of the issues raised.

Yes hydrogen is generated and this process should be conducted in open air and in a wide top non covered container ...... but unless you are running high currents .... like well over 5 amps the risk presented by the hydrogen is pretty low ....... as for sparks .... yeh of course it is best to turn off when changing contacts ...... but in over 12 months continuous operation of a bath and changing contacts with the power on ..... I have not seen a spark on an system under 5 amps.

Corrosion of the anode is an issue ..... scrap steel will work but it will disapear quickly and contaminate the bath ...... I and many others have used scrap stanless steel plate ..... and it works well and seems to last reasoanbly well and does not seem to contaminate the bath ...... if you can get carbon rods or carbon sheets ... great its suposed to be the way to go.

It is important to remember this is not a fast process ..... (but it aint as slow as molasis or tomato sauce) ..... and trying to push it is not helpfull ...... it is also a process that does not scale up convienienly ...... on a small scale it is simple convienient and pretty safe.

Yeh there is an issue with hydrogen embrittlement ...... but this can be curcumvented by baking the article afterward at a moderate heat.

Like any rust removal process it is best to remove the great bulk of the rust and dirt by mechanical means before electrolisising.


THE big benifit with electrolisis is .... it does not remove any sound material and it pretty much does not damage the item in any way regardless of how long the item is in the bath.

Unlike all the various pickling baths .... and I include molasis and tomato sauce in this group ...... these baths work because they are corrosive and for no other significant reason ...... if you leave stuff in them long enough they will disolve completly ...leave something in them a little too long and you will wreck it.

I've tried or know people who have tried just about every method of rust removal ........ lots of them are just pointless and nothing more than garrage tales or so risky it does not matter.

The only reason molasis ever got a gurnsey was because farmers had it by the drum full and it was cheap.

The only bath or chemical method I can be bothered with or will risk is electrolisis .... and only on a small scale.


Ther IS NO substitute for a scraper, or a wire brush.

Blasting has moved a very long way in recent years ..... it has become much more viable and affordable for everybody ...... it is quick and effective.

If you are worried about the agression or some of the other issues ...... look into some of the alternative media.

A cheap blasting cabinet and a couple of choices of media and you will not bother pissing arround with all the novelty methods.

Garnet... available is a couple of sizes is possibly the hardest hitting.

Silicon carbide and aluminium oxide are availble in a range of grits, but are expensive.

Crushed glass or glass bead is a bit softer and leaves a smoother finish ... this is favoured in the engine rebuild industry.

Wallnut or Macadamia shell is the old school choice for a gentile choice

there are modern plastic bead grits that work exceptionally well while being gentle.

The current funky thing is soda blasting ...either wet or dry and this is so controllable they use it to blast paint off fibreglass.

I would not consider electrolisising an engine block ...... there are far more effective and appropriate methods ... either glass bead or soda blast ... inside and out and before you machine.

The front end you are better of with the old school scraper and wire brush then finish it off with glass bead or garnett.

cheers